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  • Android Remote Service Keeps Restarting

    - by user244190
    Ok so I've built an app that uses a remote service to do some real time GPS tracking. I am using the below code to start and bind to the service. The remote service uses aidl, sets up a notification icon, runs the GPS and locationListener. In onLocationChanged, a handler sends data back to the caller via the callback. Pretty much straight out of the examples and resources online. I want to allow the service to continue running even if the app closes. When the app is restarted, I want the app to again bind to the service (using the existing service if running) and again receive data from the tracker. I currently have the app mode set to singleTask and cannot use singleinstance due to another issue. My problem is that quit often even after the app and service are shut down either from the app itself, or from AdvancedTaskKiller, or a Forceclose, the service will restart and initialize the GPS. touching on the notification will open the app. I again stop the tracking which removes the notification and turns off the GPS Close the app, and again after a few seconds the service restarts. The only way to stop it is to power off the phone. What can I do to stop this from happening. Does it have to do with the mode of operation? START_NOT_STICKY or START_REDELIVER_INTENT? Or do I need to use stopSelf()? My understanding is that if the service is not running when I use bindService() that the service will be created...so do I really need to use start/stopService also? I thought I would need to use it if I want the service to run even after the app is closed. That is why i do not unbind/stop the service in onDestroy(). Is this correct? I've not seen any other info an this, so I,m not sure where to look. Please Help! Thanks Patrick //Remote Service Startup try{ startService(); }catch (Exception e) { Toast.makeText(ctx, e.getMessage().toString(), Toast.LENGTH_SHORT).show(); } } try{ bindService(); }catch (Exception e) { Toast.makeText(ctx, e.getMessage().toString(), Toast.LENGTH_SHORT).show(); } //Remote service shutdown try { unbindService(); }catch(Exception e) { Toast.makeText(ctx, e.getMessage().toString(), Toast.LENGTH_SHORT).show(); } try{ stopService(); }catch(Exception e) { Toast.makeText(ctx, e.getMessage().toString(), Toast.LENGTH_SHORT).show(); } private void startService() { if( myAdapter.trackServiceStarted() ) { if(SETTING_DEBUG_MODE) Toast.makeText(this, "Service already started", Toast.LENGTH_SHORT).show(); started = true; if(!myAdapter.trackDataExists()) insertTrackData(); updateServiceStatus(); } else { startService( new Intent ( "com.codebase.TRACKING_SERVICE" ) ); Log.d( "startService()", "startService()" ); started = true; updateServiceStatus(); } } private void stopService() { stopService( new Intent ( "com.codebase.TRACKING_SERVICE" ) ); Log.d( "stopService()", "stopService()" ); started = false; updateServiceStatus(); } private void bindService() { bindService(new Intent(ITrackingService.class.getName()), mConnection, Context.BIND_AUTO_CREATE); bindService(new Intent(ITrackingSecondary.class.getName()), mTrackingSecondaryConnection, Context.BIND_AUTO_CREATE); started = true; } private void unbindService() { try { mTrackingService.unregisterCallback(mCallback); } catch (RemoteException e) { // There is nothing special we need to do if the service // has crashed. e.getMessage(); } try { unbindService(mTrackingSecondaryConnection); unbindService(mConnection); } catch (Exception e) { // There is nothing special we need to do if the service // has crashed. e.getMessage(); } started = false; } private ServiceConnection mConnection = new ServiceConnection() { public void onServiceConnected(ComponentName className, IBinder service) { // This is called when the connection with the service has been // established, giving us the service object we can use to // interact with the service. We are communicating with our // service through an IDL interface, so get a client-side // representation of that from the raw service object. mTrackingService = ITrackingService.Stub.asInterface(service); // We want to monitor the service for as long as we are // connected to it. try { mTrackingService.registerCallback(mCallback); } catch (RemoteException e) { // In this case the service has crashed before we could even // do anything with it; we can count on soon being // disconnected (and then reconnected if it can be restarted) // so there is no need to do anything here. } } public void onServiceDisconnected(ComponentName className) { // This is called when the connection with the service has been // unexpectedly disconnected -- that is, its process crashed. mTrackingService = null; } }; private ServiceConnection mTrackingSecondaryConnection = new ServiceConnection() { public void onServiceConnected(ComponentName className, IBinder service) { // Connecting to a secondary interface is the same as any // other interface. mTrackingSecondaryService = ITrackingSecondary.Stub.asInterface(service); try{ mTrackingSecondaryService.setTimePrecision(SETTING_TIME_PRECISION); mTrackingSecondaryService.setDistancePrecision(SETTING_DISTANCE_PRECISION); } catch (RemoteException e) { // In this case the service has crashed before we could even // do anything with it; we can count on soon being // disconnected (and then reconnected if it can be restarted) // so there is no need to do anything here. } } public void onServiceDisconnected(ComponentName className) { mTrackingSecondaryService = null; } }; //TrackService onDestry() public void onDestroy() { try{ if(lm != null) { lm.removeUpdates(this); } if(mNotificationManager != null) { mNotificationManager.cancel(R.string.local_service_started); } Toast.makeText(this, "Service stopped", Toast.LENGTH_SHORT).show(); }catch (Exception e){ Toast.makeText(this, e.getMessage(), Toast.LENGTH_SHORT).show(); } // Unregister all callbacks. mCallbacks.kill(); // Remove the next pending message to increment the counter, stopping // the increment loop. mHandler.removeMessages(REPORT_MSG); super.onDestroy(); } ServiceConnectionLeaked: I'm seeing a lot of these: 04-21 09:25:23.347: ERROR/ActivityThread(3246): Activity com.codebase.GPSTest has leaked ServiceConnection com.codebase.GPSTest$6@4482d428 that was originally bound here 04-21 09:25:23.347: ERROR/ActivityThread(3246): android.app.ServiceConnectionLeaked: Activity com.codebase.GPSTest has leaked ServiceConnection com.codebase.GPSTest$6@4482d428 that was originally bound here 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread$PackageInfo$ServiceDispatcher.<init>(ActivityThread.java:977) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread$PackageInfo.getServiceDispatcher(ActivityThread.java:872) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ApplicationContext.bindService(ApplicationContext.java:796) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.content.ContextWrapper.bindService(ContextWrapper.java:337) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at com.codebase.GPSTest.bindService(GPSTest.java:2206) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at com.codebase.GPSTest.onStartStopClick(GPSTest.java:1589) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at com.codebase.GPSTest.onResume(GPSTest.java:1210) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1149) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.Activity.performResume(Activity.java:3763) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2937) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2965) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2516) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3625) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.access$2300(ActivityThread.java:119) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1867) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.os.Handler.dispatchMessage(Handler.java:99) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.os.Looper.loop(Looper.java:123) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at android.app.ActivityThread.main(ActivityThread.java:4363) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at java.lang.reflect.Method.invokeNative(Native Method) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at java.lang.reflect.Method.invoke(Method.java:521) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 04-21 09:25:23.347: ERROR/ActivityThread(3246): at dalvik.system.NativeStart.main(Native Method) And These: Is this ok, or do I need to make sure i deactivate/close 04-21 09:58:55.487: INFO/dalvikvm(3440): Uncaught exception thrown by finalizer (will be discarded): 04-21 09:58:55.487: INFO/dalvikvm(3440): Ljava/lang/IllegalStateException;: Finalizing cursor android.database.sqlite.SQLiteCursor@447ef258 on gps_data that has not been deactivated or closed 04-21 09:58:55.487: INFO/dalvikvm(3440): at android.database.sqlite.SQLiteCursor.finalize(SQLiteCursor.java:596) 04-21 09:58:55.487: INFO/dalvikvm(3440): at dalvik.system.NativeStart.run(Native Method)

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  • OpenLDAP and SSL

    - by Stormshadow
    I am having trouble trying to connect to a secure OpenLDAP server which I have set up. On running my LDAP client code java -Djavax.net.debug=ssl LDAPConnector I get the following exception trace (java version 1.6.0_17) trigger seeding of SecureRandom done seeding SecureRandom %% No cached client session *** ClientHello, TLSv1 RandomCookie: GMT: 1256110124 bytes = { 224, 19, 193, 148, 45, 205, 108, 37, 101, 247, 112, 24, 157, 39, 111, 177, 43, 53, 206, 224, 68, 165, 55, 185, 54, 203, 43, 91 } Session ID: {} Cipher Suites: [SSL_RSA_WITH_RC4_128_MD5, SSL_RSA_WITH_RC4_128_SHA, TLS_RSA_WITH_AES_128_CBC_SHA, TLS_DHE_RSA_WITH_AES_128_CBC_SHA, TLS_DHE_DSS_WITH_AES_128_CBC_SHA, SSL_RSA_W ITH_3DES_EDE_CBC_SHA, SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA, SSL_DHE_DSS_WITH_3DES_EDE_CBC_SHA, SSL_RSA_WITH_DES_CBC_SHA, SSL_DHE_RSA_WITH_DES_CBC_SHA, SSL_DHE_DSS_WITH_DES_CBC_SH A, SSL_RSA_EXPORT_WITH_RC4_40_MD5, SSL_RSA_EXPORT_WITH_DES40_CBC_SHA, SSL_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA, SSL_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA] Compression Methods: { 0 } *** Thread-0, WRITE: TLSv1 Handshake, length = 73 Thread-0, WRITE: SSLv2 client hello message, length = 98 Thread-0, received EOFException: error Thread-0, handling exception: javax.net.ssl.SSLHandshakeException: Remote host closed connection during handshake Thread-0, SEND TLSv1 ALERT: fatal, description = handshake_failure Thread-0, WRITE: TLSv1 Alert, length = 2 Thread-0, called closeSocket() main, handling exception: javax.net.ssl.SSLHandshakeException: Remote host closed connection during handshake javax.naming.CommunicationException: simple bind failed: ldap.natraj.com:636 [Root exception is javax.net.ssl.SSLHandshakeException: Remote host closed connection during hands hake] at com.sun.jndi.ldap.LdapClient.authenticate(Unknown Source) at com.sun.jndi.ldap.LdapCtx.connect(Unknown Source) at com.sun.jndi.ldap.LdapCtx.<init>(Unknown Source) at com.sun.jndi.ldap.LdapCtxFactory.getUsingURL(Unknown Source) at com.sun.jndi.ldap.LdapCtxFactory.getUsingURLs(Unknown Source) at com.sun.jndi.ldap.LdapCtxFactory.getLdapCtxInstance(Unknown Source) at com.sun.jndi.ldap.LdapCtxFactory.getInitialContext(Unknown Source) at javax.naming.spi.NamingManager.getInitialContext(Unknown Source) at javax.naming.InitialContext.getDefaultInitCtx(Unknown Source) at javax.naming.InitialContext.init(Unknown Source) at javax.naming.InitialContext.<init>(Unknown Source) at javax.naming.directory.InitialDirContext.<init>(Unknown Source) at LDAPConnector.CallSecureLDAPServer(LDAPConnector.java:43) at LDAPConnector.main(LDAPConnector.java:237) Caused by: javax.net.ssl.SSLHandshakeException: Remote host closed connection during handshake at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(Unknown Source) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.readDataRecord(Unknown Source) at com.sun.net.ssl.internal.ssl.AppInputStream.read(Unknown Source) at java.io.BufferedInputStream.fill(Unknown Source) at java.io.BufferedInputStream.read1(Unknown Source) at java.io.BufferedInputStream.read(Unknown Source) at com.sun.jndi.ldap.Connection.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Caused by: java.io.EOFException: SSL peer shut down incorrectly at com.sun.net.ssl.internal.ssl.InputRecord.read(Unknown Source) ... 9 more I am able to connect to the same secure LDAP server however if I use another version of java (1.6.0_14) I have created and installed the server certificates in the cacerts of both the JRE's as mentioned in this guide -- OpenLDAP with SSL When I run ldapsearch -x on the server I get # extended LDIF # # LDAPv3 # base <dc=localdomain> (default) with scope subtree # filter: (objectclass=*) # requesting: ALL # # localdomain dn: dc=localdomain objectClass: top objectClass: dcObject objectClass: organization o: localdomain dc: localdomain # admin, localdomain dn: cn=admin,dc=localdomain objectClass: simpleSecurityObject objectClass: organizationalRole cn: admin description: LDAP administrator # search result search: 2 result: 0 Success # numResponses: 3 # numEntries: 2 On running openssl s_client -connect ldap.natraj.com:636 -showcerts , I obtain the self signed certificate. My slapd.conf file is as follows ####################################################################### # Global Directives: # Features to permit #allow bind_v2 # Schema and objectClass definitions include /etc/ldap/schema/core.schema include /etc/ldap/schema/cosine.schema include /etc/ldap/schema/nis.schema include /etc/ldap/schema/inetorgperson.schema # Where the pid file is put. The init.d script # will not stop the server if you change this. pidfile /var/run/slapd/slapd.pid # List of arguments that were passed to the server argsfile /var/run/slapd/slapd.args # Read slapd.conf(5) for possible values loglevel none # Where the dynamically loaded modules are stored modulepath /usr/lib/ldap moduleload back_hdb # The maximum number of entries that is returned for a search operation sizelimit 500 # The tool-threads parameter sets the actual amount of cpu's that is used # for indexing. tool-threads 1 ####################################################################### # Specific Backend Directives for hdb: # Backend specific directives apply to this backend until another # 'backend' directive occurs backend hdb ####################################################################### # Specific Backend Directives for 'other': # Backend specific directives apply to this backend until another # 'backend' directive occurs #backend <other> ####################################################################### # Specific Directives for database #1, of type hdb: # Database specific directives apply to this databasse until another # 'database' directive occurs database hdb # The base of your directory in database #1 suffix "dc=localdomain" # rootdn directive for specifying a superuser on the database. This is needed # for syncrepl. rootdn "cn=admin,dc=localdomain" # Where the database file are physically stored for database #1 directory "/var/lib/ldap" # The dbconfig settings are used to generate a DB_CONFIG file the first # time slapd starts. They do NOT override existing an existing DB_CONFIG # file. You should therefore change these settings in DB_CONFIG directly # or remove DB_CONFIG and restart slapd for changes to take effect. # For the Debian package we use 2MB as default but be sure to update this # value if you have plenty of RAM dbconfig set_cachesize 0 2097152 0 # Sven Hartge reported that he had to set this value incredibly high # to get slapd running at all. See http://bugs.debian.org/303057 for more # information. # Number of objects that can be locked at the same time. dbconfig set_lk_max_objects 1500 # Number of locks (both requested and granted) dbconfig set_lk_max_locks 1500 # Number of lockers dbconfig set_lk_max_lockers 1500 # Indexing options for database #1 index objectClass eq # Save the time that the entry gets modified, for database #1 lastmod on # Checkpoint the BerkeleyDB database periodically in case of system # failure and to speed slapd shutdown. checkpoint 512 30 # Where to store the replica logs for database #1 # replogfile /var/lib/ldap/replog # The userPassword by default can be changed # by the entry owning it if they are authenticated. # Others should not be able to see it, except the # admin entry below # These access lines apply to database #1 only access to attrs=userPassword,shadowLastChange by dn="cn=admin,dc=localdomain" write by anonymous auth by self write by * none # Ensure read access to the base for things like # supportedSASLMechanisms. Without this you may # have problems with SASL not knowing what # mechanisms are available and the like. # Note that this is covered by the 'access to *' # ACL below too but if you change that as people # are wont to do you'll still need this if you # want SASL (and possible other things) to work # happily. access to dn.base="" by * read # The admin dn has full write access, everyone else # can read everything. access to * by dn="cn=admin,dc=localdomain" write by * read # For Netscape Roaming support, each user gets a roaming # profile for which they have write access to #access to dn=".*,ou=Roaming,o=morsnet" # by dn="cn=admin,dc=localdomain" write # by dnattr=owner write ####################################################################### # Specific Directives for database #2, of type 'other' (can be hdb too): # Database specific directives apply to this databasse until another # 'database' directive occurs #database <other> # The base of your directory for database #2 #suffix "dc=debian,dc=org" ####################################################################### # SSL: # Uncomment the following lines to enable SSL and use the default # snakeoil certificates. #TLSCertificateFile /etc/ssl/certs/ssl-cert-snakeoil.pem #TLSCertificateKeyFile /etc/ssl/private/ssl-cert-snakeoil.key TLSCipherSuite TLS_RSA_AES_256_CBC_SHA TLSCACertificateFile /etc/ldap/ssl/server.pem TLSCertificateFile /etc/ldap/ssl/server.pem TLSCertificateKeyFile /etc/ldap/ssl/server.pem My ldap.conf file is # # LDAP Defaults # # See ldap.conf(5) for details # This file should be world readable but not world writable. HOST ldap.natraj.com PORT 636 BASE dc=localdomain URI ldaps://ldap.natraj.com TLS_CACERT /etc/ldap/ssl/server.pem TLS_REQCERT allow #SIZELIMIT 12 #TIMELIMIT 15 #DEREF never

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  • NoClassDefFoundError and Netty

    - by Dmytro Leonenko
    Hi. First to say I'm n00b in Java. I can understand most concepts but in my situation I want somebody to help me. I'm using JBoss Netty to handle simple http request and using MemCachedClient check existence of client ip in memcached. import org.jboss.netty.channel.ChannelHandler; import static org.jboss.netty.handler.codec.http.HttpHeaders.*; import static org.jboss.netty.handler.codec.http.HttpHeaders.Names.*; import static org.jboss.netty.handler.codec.http.HttpResponseStatus.*; import static org.jboss.netty.handler.codec.http.HttpVersion.*; import com.danga.MemCached.*; import java.util.List; import java.util.Map; import java.util.Map.Entry; import java.util.Set; import org.jboss.netty.buffer.ChannelBuffer; import org.jboss.netty.buffer.ChannelBuffers; import org.jboss.netty.channel.ChannelFuture; import org.jboss.netty.channel.ChannelFutureListener; import org.jboss.netty.channel.ChannelHandlerContext; import org.jboss.netty.channel.ExceptionEvent; import org.jboss.netty.channel.MessageEvent; import org.jboss.netty.channel.SimpleChannelUpstreamHandler; import org.jboss.netty.handler.codec.http.Cookie; import org.jboss.netty.handler.codec.http.CookieDecoder; import org.jboss.netty.handler.codec.http.CookieEncoder; import org.jboss.netty.handler.codec.http.DefaultHttpResponse; import org.jboss.netty.handler.codec.http.HttpChunk; import org.jboss.netty.handler.codec.http.HttpChunkTrailer; import org.jboss.netty.handler.codec.http.HttpRequest; import org.jboss.netty.handler.codec.http.HttpResponse; import org.jboss.netty.handler.codec.http.HttpResponseStatus; import org.jboss.netty.handler.codec.http.QueryStringDecoder; import org.jboss.netty.util.CharsetUtil; /** * @author <a href="http://www.jboss.org/netty/">The Netty Project</a> * @author Andy Taylor ([email protected]) * @author <a href="http://gleamynode.net/">Trustin Lee</a> * * @version $Rev: 2368 $, $Date: 2010-10-18 17:19:03 +0900 (Mon, 18 Oct 2010) $ */ @SuppressWarnings({"ALL"}) public class HttpRequestHandler extends SimpleChannelUpstreamHandler { private HttpRequest request; private boolean readingChunks; /** Buffer that stores the response content */ private final StringBuilder buf = new StringBuilder(); protected MemCachedClient mcc = new MemCachedClient(); private static SockIOPool poolInstance = null; static { // server list and weights String[] servers = { "lcalhost:11211" }; //Integer[] weights = { 3, 3, 2 }; Integer[] weights = {1}; // grab an instance of our connection pool SockIOPool pool = SockIOPool.getInstance(); // set the servers and the weights pool.setServers(servers); pool.setWeights(weights); // set some basic pool settings // 5 initial, 5 min, and 250 max conns // and set the max idle time for a conn // to 6 hours pool.setInitConn(5); pool.setMinConn(5); pool.setMaxConn(250); pool.setMaxIdle(21600000); //1000 * 60 * 60 * 6 // set the sleep for the maint thread // it will wake up every x seconds and // maintain the pool size pool.setMaintSleep(30); // set some TCP settings // disable nagle // set the read timeout to 3 secs // and don't set a connect timeout pool.setNagle(false); pool.setSocketTO(3000); pool.setSocketConnectTO(0); // initialize the connection pool pool.initialize(); // lets set some compression on for the client // compress anything larger than 64k //mcc.setCompressEnable(true); //mcc.setCompressThreshold(64 * 1024); } @Override public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception { HttpRequest request = this.request = (HttpRequest) e.getMessage(); if(mcc.get(request.getHeader("X-Real-Ip")) != null) { HttpResponse response = new DefaultHttpResponse(HTTP_1_1, OK); response.setHeader("X-Accel-Redirect", request.getUri()); ctx.getChannel().write(response).addListener(ChannelFutureListener.CLOSE); } else { sendError(ctx, NOT_FOUND); } } private void writeResponse(MessageEvent e) { // Decide whether to close the connection or not. boolean keepAlive = isKeepAlive(request); // Build the response object. HttpResponse response = new DefaultHttpResponse(HTTP_1_1, OK); response.setContent(ChannelBuffers.copiedBuffer(buf.toString(), CharsetUtil.UTF_8)); response.setHeader(CONTENT_TYPE, "text/plain; charset=UTF-8"); if (keepAlive) { // Add 'Content-Length' header only for a keep-alive connection. response.setHeader(CONTENT_LENGTH, response.getContent().readableBytes()); } // Encode the cookie. String cookieString = request.getHeader(COOKIE); if (cookieString != null) { CookieDecoder cookieDecoder = new CookieDecoder(); Set<Cookie> cookies = cookieDecoder.decode(cookieString); if(!cookies.isEmpty()) { // Reset the cookies if necessary. CookieEncoder cookieEncoder = new CookieEncoder(true); for (Cookie cookie : cookies) { cookieEncoder.addCookie(cookie); } response.addHeader(SET_COOKIE, cookieEncoder.encode()); } } // Write the response. ChannelFuture future = e.getChannel().write(response); // Close the non-keep-alive connection after the write operation is done. if (!keepAlive) { future.addListener(ChannelFutureListener.CLOSE); } } @Override public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception { e.getCause().printStackTrace(); e.getChannel().close(); } private void sendError(ChannelHandlerContext ctx, HttpResponseStatus status) { HttpResponse response = new DefaultHttpResponse(HTTP_1_1, status); response.setHeader(CONTENT_TYPE, "text/plain; charset=UTF-8"); response.setContent(ChannelBuffers.copiedBuffer( "Failure: " + status.toString() + "\r\n", CharsetUtil.UTF_8)); // Close the connection as soon as the error message is sent. ctx.getChannel().write(response).addListener(ChannelFutureListener.CLOSE); } } When I try to send request like http://127.0.0.1:8090/1/2/3 I'm getting java.lang.NoClassDefFoundError: com/danga/MemCached/MemCachedClient at httpClientValidator.server.HttpRequestHandler.<clinit>(HttpRequestHandler.java:66) I believe it's not related to classpath. May be it's related to context in which mcc doesn't exist. Any help appreciated EDIT: Original code http://docs.jboss.org/netty/3.2/xref/org/jboss/netty/example/http/snoop/package-summary.html I've modified some parts to fit my needs.

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  • Communicating between C# application and Android app via bluetooth

    - by Akki
    The android application acts as a server in this case. I have a main activity which creates a Thread to handle serverSocket and a different thread to handle the socket connection. I am using a uuid common to C# and android. I am using 32feet bluetooth library for C#. The errors i am facing are 1) My logcat shows this debug log Error while doing socket.connect()1 java.io.IOException: File descriptor in bad state Message: File descriptor in bad state Localized Message: File descriptor in bad state Received : Testing Connection Count of Thread is : 1 2) When i try to send something via C# app the second time, this exception is thrown: A first chance exception of type 'System.InvalidOperationException' occurred in System.dll System.InvalidOperationException: BeginConnect cannot be called while another asynchronous operation is in progress on the same Socket. at System.Net.Sockets.Socket.DoBeginConnect(EndPoint endPointSnapshot, SocketAddress socketAddress, LazyAsyncResult asyncResult) at System.Net.Sockets.Socket.BeginConnect(EndPoint remoteEP, AsyncCallback callback, Object state) at InTheHand.Net.Bluetooth.Msft.SocketBluetoothClient.BeginConnect(BluetoothEndPoint remoteEP, AsyncCallback requestCallback, Object state) at InTheHand.Net.Sockets.BluetoothClient.BeginConnect(BluetoothEndPoint remoteEP, AsyncCallback requestCallback, Object state) at InTheHand.Net.Sockets.BluetoothClient.BeginConnect(BluetoothAddress address, Guid service, AsyncCallback requestCallback, Object state) at BTSyncClient.Form1.connect() in c:\users\----\documents\visual studio 2010\Projects\TestClient\TestClient\Form1.cs:line 154 I only know android application programming and i designed the C# by learning bit and pieces. FYI, My android phone is galaxy s with ICS running on it.Please point out my mistakes.. Source codes : C# Code using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Threading; using System.Net.Sockets; using InTheHand.Net.Bluetooth; using InTheHand.Windows.Forms; using InTheHand.Net.Sockets; using InTheHand.Net; namespace BTSyncClient { public partial class Form1 : Form { BluetoothClient myself; BluetoothDeviceInfo bTServerDevice; private Guid uuid = Guid.Parse("00001101-0000-1000-8000-00805F9B34FB"); bool isConnected; public Form1() { InitializeComponent(); if (BluetoothRadio.IsSupported) { myself = new BluetoothClient(); } } private void Form1_Load(object sender, EventArgs e) { } private void button1_Click(object sender, EventArgs e) { connect(); } private void Form1_FormClosing(object sender, FormClosingEventArgs e) { try { myself.GetStream().Close(); myself.Dispose(); } catch (Exception ex) { Console.Out.WriteLine(ex); } } private void button2_Click(object sender, EventArgs e) { SelectBluetoothDeviceDialog dialog = new SelectBluetoothDeviceDialog(); DialogResult result = dialog.ShowDialog(this); if(result.Equals(DialogResult.OK)){ bTServerDevice = dialog.SelectedDevice; } } private void callback(IAsyncResult ar) { String msg = (String)ar.AsyncState; if (ar.IsCompleted) { isConnected = myself.Connected; if (myself.Connected) { UTF8Encoding encoder = new UTF8Encoding(); NetworkStream stream = myself.GetStream(); if (!stream.CanWrite) { MessageBox.Show("Stream is not Writable"); } System.IO.StreamWriter mywriter = new System.IO.StreamWriter(stream, Encoding.UTF8); mywriter.WriteLine(msg); mywriter.Flush(); } else MessageBox.Show("Damn thing isnt connected"); } } private void connect() { try { if (bTServerDevice != null) { myself.BeginConnect(bTServerDevice.DeviceAddress, uuid, new AsyncCallback(callback) , message.Text); } } catch (Exception e) { Console.Out.WriteLine(e); } } } } Server Thread import java.io.IOException; import java.util.UUID; import android.bluetooth.BluetoothAdapter; import android.bluetooth.BluetoothServerSocket; import android.bluetooth.BluetoothSocket; import android.util.Log; public class ServerSocketThread extends Thread { private static final String TAG = "TestApp"; private BluetoothAdapter btAdapter; private BluetoothServerSocket serverSocket; private boolean stopMe; private static final UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); //private static final UUID uuid = UUID.fromString("6e58c9d5-b0b6-4009-ad9b-fd9481aef9b3"); private static final String SERVICE_NAME = "TestService"; public ServerSocketThread() { stopMe = false; btAdapter = BluetoothAdapter.getDefaultAdapter(); try { serverSocket = btAdapter.listenUsingRfcommWithServiceRecord(SERVICE_NAME, uuid); } catch (IOException e) { Log.d(TAG,e.toString()); } } public void signalStop(){ stopMe = true; } public void run(){ Log.d(TAG,"In ServerThread"); BluetoothSocket socket = null; while(!stopMe){ try { socket = serverSocket.accept(); } catch (IOException e) { break; } if(socket != null){ AcceptThread newClientConnection = new AcceptThread(socket); newClientConnection.start(); } } Log.d(TAG,"Server Thread now dead"); } // Will cancel the listening socket and cause the thread to finish public void cancel(){ try { serverSocket.close(); } catch (IOException e) { } } } Accept Thread import java.io.IOException; import java.io.InputStream; import java.util.Scanner; import android.bluetooth.BluetoothSocket; import android.util.Log; public class AcceptThread extends Thread { private BluetoothSocket socket; private String TAG = "TestApp"; static int count = 0; public AcceptThread(BluetoothSocket Socket) { socket = Socket; } volatile boolean isError; String output; String error; public void run() { Log.d(TAG, "AcceptThread Started"); isError = false; try { socket.connect(); } catch (IOException e) { Log.d(TAG,"Error while doing socket.connect()"+ ++count); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } InputStream in = null; try { in = socket.getInputStream(); } catch (IOException e) { Log.d(TAG,"Error while doing socket.getInputStream()"); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } Scanner istream = new Scanner(in); if (istream.hasNextLine()) { Log.d(TAG, "Received : "+istream.nextLine()); Log.d(TAG,"Count of Thread is : " + count); } istream.close(); try { in.close(); } catch (IOException e) { Log.d(TAG,"Error while doing in.close()"); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } try { socket.close(); } catch (IOException e) { Log.d(TAG,"Error while doing socket.close()"); Log.d(TAG, e.toString()); Log.d(TAG,"Message: "+e.getLocalizedMessage()); Log.d(TAG,"Localized Message: "+e.getMessage()); isError = true; } } }

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  • Why "menus" unit is finalized too early?

    - by Harriv
    I tested my application with FastMM and FullDebugMode turned on, since I had some shutdown problems. After solving bunch of my own problems FastMM started to complain about calling virtual method on a freed object in TPopupList. I tried to move the menus unit as early as possible in uses so that it would be finalized last, but it didn't help. Is this real problem, a bug in vcl or false alarm from FastMM? Here's the full report from FastMM: FastMM has detected an attempt to call a virtual method on a freed object. An access violation will now be raised in order to abort the current operation. Freed object class: TPopupList Virtual method: Offset +16 Virtual method address: 4714E4 The allocation number was: 220 The object was allocated by thread 0x1CC0, and the stack trace (return addresses) at the time was: 403216 [sys\system.pas][System][System.@GetMem][2654] 404A4F [sys\system.pas][System][System.TObject.NewInstance][8807] 404E16 [sys\system.pas][System][System.@ClassCreate][9472] 404A84 [sys\system.pas][System][System.TObject.Create][8822] 7F2602 [Menus.pas][Menus][Menus.Menus][4223] 40570F [sys\system.pas][System][System.InitUnits][11397] 405777 [sys\system.pas][System][System.@StartExe][11462] 40844F [SysInit.pas][SysInit][SysInit.@InitExe][663] 7F6368 [PCCSServer.dpr][PCCSServer][PCCSServer.PCCSServer][148] 7C90DCBA [ZwSetInformationThread] 7C817077 [Unknown function at RegisterWaitForInputIdle] The object was subsequently freed by thread 0x1CC0, and the stack trace (return addresses) at the time was: 403232 [sys\system.pas][System][System.@FreeMem][2699] 404A6D [sys\system.pas][System][System.TObject.FreeInstance][8813] 404E61 [sys\system.pas][System][System.@ClassDestroy][9513] 428D15 [common\Classes.pas][Classes][Classes.TList.Destroy][2914] 404AB3 [sys\system.pas][System][System.TObject.Free][8832] 472091 [Menus.pas][Menus][Menus.Finalization][4228] 4056A7 [sys\system.pas][System][System.FinalizeUnits][11256] 4056BF [sys\system.pas][System][System.FinalizeUnits][11261] 7C9032A8 [RtlConvertUlongToLargeInteger] 7C90327A [RtlConvertUlongToLargeInteger] 7C92AA0F [Unknown function at towlower] The current thread ID is 0x1CC0, and the stack trace (return addresses) leading to this error is: 4714B8 [Menus.pas][Menus][Menus.TPopupList.MainWndProc][3779] 435BB2 [common\Classes.pas][Classes][Classes.StdWndProc][11583] 7E418734 [Unknown function at GetDC] 7E418816 [Unknown function at GetDC] 7E428EA0 [Unknown function at DefWindowProcW] 7E428EEC [Unknown function at DefWindowProcW] 7C90E473 [KiUserCallbackDispatcher] 7E42B1A8 [DestroyWindow] 47CE31 [Controls.pas][Controls][Controls.TWinControl.DestroyWindowHandle][6857] 493BE4 [Forms.pas][Forms][Forms.TCustomForm.DestroyWindowHandle][4564] 4906D9 [Forms.pas][Forms][Forms.TCustomForm.Destroy][2929] Current memory dump of 256 bytes starting at pointer address 7FF9CFF0: 2C FE 82 00 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 C4 A3 2D 0C 00 00 00 00 B1 D0 F9 7F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 C0 00 00 00 16 32 40 00 9D 5B 40 00 C8 5B 40 00 CE 82 40 00 3C 40 91 7C B0 B1 94 7C 0A 77 92 7C 84 77 92 7C 7C F0 96 7C 94 B3 94 7C 84 77 92 7C C0 1C 00 00 32 32 40 00 12 5B 40 00 EF 69 40 00 BA 20 47 00 A7 56 40 00 BF 56 40 00 A8 32 90 7C 7A 32 90 7C 0F AA 92 7C 0A 77 92 7C 84 77 92 7C C0 1C 00 00 0E 00 00 00 00 00 00 00 C7 35 65 59 2C FE 82 00 80 80 80 80 80 80 80 80 80 80 38 CA 9A A6 80 80 80 80 80 80 00 00 00 00 51 D1 F9 7F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 C1 00 00 00 16 32 40 00 9D 5B 40 00 C8 5B 40 00 CE 82 40 00 3C 40 91 7C B0 B1 94 7C 0A 77 92 7C 84 77 92 7C 7C F0 96 7C 94 B3 94 7C 84 77 92 7C , þ ‚ . € € € € € € € € € € € € € € € € Ä £ - . . . . . ± Ð ù . . . . . . . . . . . . . . . . À . . . . 2 @ . [ @ . È [ @ . Î ‚ @ . < @ ‘ | ° ± ” | . w ’ | „ w ’ | | ð – | ” ³ ” | „ w ’ | À . . . 2 2 @ . . [ @ . ï i @ . º G . § V @ . ¿ V @ . ¨ 2 | z 2 | . ª ’ | . w ’ | „ w ’ | À . . . . . . . . . . . Ç 5 e Y , þ ‚ . € € € € € € € € € € 8 Ê š ¦ € € € € € € . . . . Q Ñ ù . . . . . . . . . . . . . . . . Á . . . . 2 @ . [ @ . È [ @ . Î ‚ @ . < @ ‘ | ° ± ” | . w ’ | „ w ’ | | ð – | ” ³ ” | „ w ’ | I'm using Delphi 2007 and FastMM 4.97.

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  • problem in concurrent web services

    - by user548750
    Hi All I have developed a web services. I am getting problem when two different user are trying to access web services concurrently. In web services two methods are there setInputParameter getUserService suppose Time User Operation 10:10 am user1 setInputParameter 10:15 am user2 setInputParameter 10:20 am user1 getUserService User1 is getting result according to the input parameter seted by user2 not by ( him own ) I am using axis2 1.4 ,eclipse ant build, My services are goes here User class service class service.xml build file testclass package com.jimmy.pojo; public class User { private String firstName; private String lastName; private String[] addressCity; public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public String[] getAddressCity() { return addressCity; } public void setAddressCity(String[] addressCity) { this.addressCity = addressCity; } } [/code] [code=java]package com.jimmy.service; import com.jimmy.pojo.User; public class UserService { private User user; public void setInputParameter(User userInput) { user = userInput; } public User getUserService() { user.setFirstName(user.getFirstName() + " changed "); if (user.getAddressCity() == null) { user.setAddressCity(new String[] { "New City Added" }); } else { user.getAddressCity()[0] = "==========="; } return user; } } [/code] [code=java]<service name="MyWebServices" scope="application"> <description> My Web Service </description> <messageReceivers> <messageReceiver mep="http://www.w3.org/2004/08/wsdl/in-only" class="org.apache.axis2.rpc.receivers.RPCInOnlyMessageReceiver" /> <messageReceiver mep="http://www.w3.org/2004/08/wsdl/in-out" class="org.apache.axis2.rpc.receivers.RPCMessageReceiver" /> </messageReceivers> <parameter name="ServiceClass">com.jimmy.service.UserService </parameter> </service>[/code] [code=java] <project name="MyWebServices" basedir="." default="generate.service"> <property name="service.name" value="UserService" /> <property name="dest.dir" value="build" /> <property name="dest.dir.classes" value="${dest.dir}/${service.name}" /> <property name="dest.dir.lib" value="${dest.dir}/lib" /> <property name="axis2.home" value="../../" /> <property name="repository.path" value="${axis2.home}/repository" /> <path id="build.class.path"> <fileset dir="${axis2.home}/lib"> <include name="*.jar" /> </fileset> </path> <path id="client.class.path"> <fileset dir="${axis2.home}/lib"> <include name="*.jar" /> </fileset> <fileset dir="${dest.dir.lib}"> <include name="*.jar" /> </fileset> </path> <target name="clean"> <delete dir="${dest.dir}" /> <delete dir="src" includes="com/jimmy/pojo/stub/**"/> </target> <target name="prepare"> <mkdir dir="${dest.dir}" /> <mkdir dir="${dest.dir}/lib" /> <mkdir dir="${dest.dir.classes}" /> <mkdir dir="${dest.dir.classes}/META-INF" /> </target> <target name="generate.service" depends="clean,prepare"> <copy file="src/META-INF/services.xml" tofile="${dest.dir.classes}/META-INF/services.xml" overwrite="true" /> <javac srcdir="src" destdir="${dest.dir.classes}" includes="com/jimmy/service/**,com/jimmy/pojo/**"> <classpath refid="build.class.path" /> </javac> <jar basedir="${dest.dir.classes}" destfile="${dest.dir}/${service.name}.aar" /> <copy file="${dest.dir}/${service.name}.aar" tofile="${repository.path}/services/${service.name}.aar" overwrite="true" /> </target> </project> [/code] [code=java]package com.jimmy.test; import javax.xml.namespace.QName; import org.apache.axis2.AxisFault; import org.apache.axis2.addressing.EndpointReference; import org.apache.axis2.client.Options; import org.apache.axis2.rpc.client.RPCServiceClient; import com.jimmy.pojo.User; public class MyWebServices { @SuppressWarnings("unchecked") public static void main(String[] args1) throws AxisFault { RPCServiceClient serviceClient = new RPCServiceClient(); Options options = serviceClient.getOptions(); EndpointReference targetEPR = new EndpointReference( "http://localhost:8080/axis2/services/MyWebServices"); options.setTo(targetEPR); // Setting the Input Parameter QName opSetQName = new QName("http://service.jimmy.com", "setInputParameter"); User user = new User(); String[] cityList = new String[] { "Bangalore", "Mumbai" }; /* We need to set this for user 2 as user 2 */ user.setFirstName("User 1 first name"); user.setLastName("User 1 Last name"); user.setAddressCity(cityList); Object[] opSetInptArgs = new Object[] { user }; serviceClient.invokeRobust(opSetQName, opSetInptArgs); // Getting the weather QName opGetWeather = new QName("http://service.jimmy.com", "getUserService"); Object[] opGetWeatherArgs = new Object[] {}; Class[] returnTypes = new Class[] { User.class }; Object[] response = serviceClient.invokeBlocking(opGetWeather, opGetWeatherArgs, returnTypes); System.out.println("Context :"+serviceClient.getServiceContext()); User result = (User) response[0]; if (result == null) { System.out.println("User is not initialized!"); return; } else { System.out.println("*********printing result********"); String[] list =result.getAddressCity(); System.out.println(result.getFirstName()); System.out.println(result.getLastName()); for (int indx = 0; indx < list.length ; indx++) { String string = result.getAddressCity()[indx]; System.out.println(string); } } } }

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  • Help with Java Program for Prime numbers

    - by Ben
    Hello everyone, I was wondering if you can help me with this program. I have been struggling with it for hours and have just trashed my code because the TA doesn't like how I executed it. I am completely hopeless and if anyone can help me out step by step, I would greatly appreciate it. In this project you will write a Java program that reads a positive integer n from standard input, then prints out the first n prime numbers. We say that an integer m is divisible by a non-zero integer d if there exists an integer k such that m = k d , i.e. if d divides evenly into m. Equivalently, m is divisible by d if the remainder of m upon (integer) division by d is zero. We would also express this by saying that d is a divisor of m. A positive integer p is called prime if its only positive divisors are 1 and p. The one exception to this rule is the number 1 itself, which is considered to be non-prime. A positive integer that is not prime is called composite. Euclid showed that there are infinitely many prime numbers. The prime and composite sequences begin as follows: Primes: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, … Composites: 1, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, 28, … There are many ways to test a number for primality, but perhaps the simplest is to simply do trial divisions. Begin by dividing m by 2, and if it divides evenly, then m is not prime. Otherwise, divide by 3, then 4, then 5, etc. If at any point m is found to be divisible by a number d in the range 2 d m-1, then halt, and conclude that m is composite. Otherwise, conclude that m is prime. A moment’s thought shows that one need not do any trial divisions by numbers d which are themselves composite. For instance, if a trial division by 2 fails (i.e. has non-zero remainder, so m is odd), then a trial division by 4, 6, or 8, or any even number, must also fail. Thus to test a number m for primality, one need only do trial divisions by prime numbers less than m. Furthermore, it is not necessary to go all the way up to m-1. One need only do trial divisions of m by primes p in the range 2 p m . To see this, suppose m 1 is composite. Then there exist positive integers a and b such that 1 < a < m, 1 < b < m, and m = ab . But if both a m and b m , then ab m, contradicting that m = ab . Hence one of a or b must be less than or equal to m . To implement this process in java you will write a function called isPrime() with the following signature: static boolean isPrime(int m, int[] P) This function will return true or false according to whether m is prime or composite. The array argument P will contain a sufficient number of primes to do the testing. Specifically, at the time isPrime() is called, array P must contain (at least) all primes p in the range 2 p m . For instance, to test m = 53 for primality, one must do successive trial divisions by 2, 3, 5, and 7. We go no further since 11 53 . Thus a precondition for the function call isPrime(53, P) is that P[0] = 2 , P[1] = 3 , P[2] = 5, and P[3] = 7 . The return value in this case would be true since all these divisions fail. Similarly to test m =143 , one must do trial divisions by 2, 3, 5, 7, and 11 (since 13 143 ). The precondition for the function call isPrime(143, P) is therefore P[0] = 2 , P[1] = 3 , P[2] = 5, P[3] = 7 , and P[4] =11. The return value in this case would be false since 11 divides 143. Function isPrime() should contain a loop that steps through array P, doing trial divisions. This loop should terminate when 2 either a trial division succeeds, in which case false is returned, or until the next prime in P is greater than m , in which case true is returned. Function main() in this project will read the command line argument n, allocate an int array of length n, fill the array with primes, then print the contents of the array to stdout according to the format described below. In the context of function main(), we will refer to this array as Primes[]. Thus array Primes[] plays a dual role in this project. On the one hand, it is used to collect, store, and print the output data. On the other hand, it is passed to function isPrime() to test new integers for primality. Whenever isPrime() returns true, the newly discovered prime will be placed at the appropriate position in array Primes[]. This process works since, as explained above, the primes needed to test an integer m range only up to m , and all of these primes (and more) will already be stored in array Primes[] when m is tested. Of course it will be necessary to initialize Primes[0] = 2 manually, then proceed to test 3, 4, … for primality using function isPrime(). The following is an outline of the steps to be performed in function main(). • Check that the user supplied exactly one command line argument which can be interpreted as a positive integer n. If the command line argument is not a single positive integer, your program will print a usage message as specified in the examples below, then exit. • Allocate array Primes[] of length n and initialize Primes[0] = 2 . • Enter a loop which will discover subsequent primes and store them as Primes[1] , Primes[2], Primes[3] , ……, Primes[n -1] . This loop should contain an inner loop which walks through successive integers and tests them for primality by calling function isPrime() with appropriate arguments. • Print the contents of array Primes[] to stdout, 10 to a line separated by single spaces. In other words Primes[0] through Primes[9] will go on line 1, Primes[10] though Primes[19] will go on line 2, and so on. Note that if n is not a multiple of 10, then the last line of output will contain fewer than 10 primes. Your program, which will be called Prime.java, will produce output identical to that of the sample runs below. (As usual % signifies the unix prompt.) % java Prime Usage: java Prime [PositiveInteger] % java Prime xyz Usage: java Prime [PositiveInteger] % java Prime 10 20 Usage: java Prime [PositiveInteger] % java Prime 75 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199 211 223 227 229 233 239 241 251 257 263 269 271 277 281 283 293 307 311 313 317 331 337 347 349 353 359 367 373 379 % 3 As you can see, inappropriate command line argument(s) generate a usage message which is similar to that of many unix commands. (Try doing the more command with no arguments to see such a message.) Your program will include a function called Usage() having signature static void Usage() that prints this message to stderr, then exits. Thus your program will contain three functions in all: main(), isPrime(), and Usage(). Each should be preceded by a comment block giving it’s name, a short description of it’s operation, and any necessary preconditions (such as those for isPrime().) See examples on the webpage.

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  • how do you make a "concurrent queue safe" lazy loader (singleton manager) in objective-c

    - by Rich
    Hi, I made this class that turns any object into a singleton, but I know that it's not "concurrent queue safe." Could someone please explain to me how to do this, or better yet, show me the code. To be clear I want to know how to use this with operation queues and dispatch queues (NSOperationQueue and Grand Central Dispatch) on iOS. Thanks in advance, Rich EDIT: I had an idea for how to do it. If someone could confirm it for me I'll do it and post the code. The idea is that proxies make queues all on their own. So if I make a mutable proxy (like Apple does in key-value coding/observing) for any object that it's supposed to return, and always return the same proxy for the same object/identifier pair (using the same kind of lazy loading technique as I used to create the singletons), the proxies would automatically queue up the any messages to the singletons, and make it totally thread safe. IMHO this seems like a lot of work to do, so I don't want to do it if it's not gonna work, or if it's gonna slow my apps down to a crawl. Here's my non-thread safe code: RMSingletonCollector.h // // RMSingletonCollector.h // RMSingletonCollector // // Created by Rich Meade-Miller on 2/11/11. // Copyright 2011 Rich Meade-Miller. All rights reserved. // #import <Foundation/Foundation.h> #import "RMWeakObjectRef.h" struct RMInitializerData { // The method may take one argument. // required SEL designatedInitializer; // data to pass to the initializer or nil. id data; }; typedef struct RMInitializerData RMInitializerData; RMInitializerData RMInitializerDataMake(SEL initializer, id data); @interface NSObject (SingletonCollector) // Returns the selector and data to pass to it (if the selector takes an argument) for use when initializing the singleton. // If you override this DO NOT call super. + (RMInitializerData)designatedInitializerForIdentifier:(NSString *)identifier; @end @interface RMSingletonCollector : NSObject { } + (id)collectionObjectForType:(NSString *)className identifier:(NSString *)identifier; + (id<RMWeakObjectReference>)referenceForObjectOfType:(NSString *)className identifier:(NSString *)identifier; + (void)destroyCollection; + (void)destroyCollectionObjectForType:(NSString *)className identifier:(NSString *)identifier; @end // ==--==--==--==--==Notifications==--==--==--==--== extern NSString *const willDestroySingletonCollection; extern NSString *const willDestroySingletonCollectionObject; RMSingletonCollector.m // // RMSingletonCollector.m // RMSingletonCollector // // Created by Rich Meade-Miller on 2/11/11. // Copyright 2011 Rich Meade-Miller. All rights reserved. // #import "RMSingletonCollector.h" #import <objc/objc-runtime.h> NSString *const willDestroySingletonCollection = @"willDestroySingletonCollection"; NSString *const willDestroySingletonCollectionObject = @"willDestroySingletonCollectionObject"; RMInitializerData RMInitializerDataMake(SEL initializer, id data) { RMInitializerData newData; newData.designatedInitializer = initializer; newData.data = data; return newData; } @implementation NSObject (SingletonCollector) + (RMInitializerData)designatedInitializerForIdentifier:(NSString *)identifier { return RMInitializerDataMake(@selector(init), nil); } @end @interface RMSingletonCollector () + (NSMutableDictionary *)singletonCollection; + (void)setSingletonCollection:(NSMutableDictionary *)newSingletonCollection; @end @implementation RMSingletonCollector static NSMutableDictionary *singletonCollection = nil; + (NSMutableDictionary *)singletonCollection { if (singletonCollection != nil) { return singletonCollection; } NSMutableDictionary *collection = [[NSMutableDictionary alloc] initWithCapacity:1]; [self setSingletonCollection:collection]; [collection release]; return singletonCollection; } + (void)setSingletonCollection:(NSMutableDictionary *)newSingletonCollection { if (newSingletonCollection != singletonCollection) { [singletonCollection release]; singletonCollection = [newSingletonCollection retain]; } } + (id)collectionObjectForType:(NSString *)className identifier:(NSString *)identifier { id obj; NSString *key; if (identifier) { key = [className stringByAppendingFormat:@".%@", identifier]; } else { key = className; } if (obj = [[self singletonCollection] objectForKey:key]) { return obj; } // dynamic creation. // get a class for Class classForName = NSClassFromString(className); if (classForName) { obj = objc_msgSend(classForName, @selector(alloc)); // if the initializer takes an argument... RMInitializerData initializerData = [classForName designatedInitializerForIdentifier:identifier]; if (initializerData.data) { // pass it. obj = objc_msgSend(obj, initializerData.designatedInitializer, initializerData.data); } else { obj = objc_msgSend(obj, initializerData.designatedInitializer); } [singletonCollection setObject:obj forKey:key]; [obj release]; } else { // raise an exception if there is no class for the specified name. NSException *exception = [NSException exceptionWithName:@"com.RMDev.RMSingletonCollector.failed_to_find_class" reason:[NSString stringWithFormat:@"SingletonCollector couldn't find class for name: %@", [className description]] userInfo:nil]; [exception raise]; [exception release]; } return obj; } + (id<RMWeakObjectReference>)referenceForObjectOfType:(NSString *)className identifier:(NSString *)identifier { id obj = [self collectionObjectForType:className identifier:identifier]; RMWeakObjectRef *objectRef = [[RMWeakObjectRef alloc] initWithObject:obj identifier:identifier]; return [objectRef autorelease]; } + (void)destroyCollection { NSDictionary *userInfo = [singletonCollection copy]; [[NSNotificationCenter defaultCenter] postNotificationName:willDestroySingletonCollection object:self userInfo:userInfo]; [userInfo release]; // release the collection and set it to nil. [self setSingletonCollection:nil]; } + (void)destroyCollectionObjectForType:(NSString *)className identifier:(NSString *)identifier { NSString *key; if (identifier) { key = [className stringByAppendingFormat:@".%@", identifier]; } else { key = className; } [[NSNotificationCenter defaultCenter] postNotificationName:willDestroySingletonCollectionObject object:[singletonCollection objectForKey:key] userInfo:nil]; [singletonCollection removeObjectForKey:key]; } @end RMWeakObjectRef.h // // RMWeakObjectRef.h // RMSingletonCollector // // Created by Rich Meade-Miller on 2/12/11. // Copyright 2011 Rich Meade-Miller. All rights reserved. // // In order to offset the performance loss from always having to search the dictionary, I made a retainable, weak object reference class. #import <Foundation/Foundation.h> @protocol RMWeakObjectReference <NSObject> @property (nonatomic, assign, readonly) id objectRef; @property (nonatomic, retain, readonly) NSString *className; @property (nonatomic, retain, readonly) NSString *objectIdentifier; @end @interface RMWeakObjectRef : NSObject <RMWeakObjectReference> { id objectRef; NSString *className; NSString *objectIdentifier; } - (RMWeakObjectRef *)initWithObject:(id)object identifier:(NSString *)identifier; - (void)objectWillBeDestroyed:(NSNotification *)notification; @end RMWeakObjectRef.m // // RMWeakObjectRef.m // RMSingletonCollector // // Created by Rich Meade-Miller on 2/12/11. // Copyright 2011 Rich Meade-Miller. All rights reserved. // #import "RMWeakObjectRef.h" #import "RMSingletonCollector.h" @implementation RMWeakObjectRef @dynamic objectRef; @synthesize className, objectIdentifier; - (RMWeakObjectRef *)initWithObject:(id)object identifier:(NSString *)identifier { if (self = [super init]) { NSString *classNameForObject = NSStringFromClass([object class]); className = classNameForObject; objectIdentifier = identifier; objectRef = object; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(objectWillBeDestroyed:) name:willDestroySingletonCollectionObject object:object]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(objectWillBeDestroyed:) name:willDestroySingletonCollection object:[RMSingletonCollector class]]; } return self; } - (id)objectRef { if (objectRef) { return objectRef; } objectRef = [RMSingletonCollector collectionObjectForType:className identifier:objectIdentifier]; return objectRef; } - (void)objectWillBeDestroyed:(NSNotification *)notification { objectRef = nil; } - (void)dealloc { [[NSNotificationCenter defaultCenter] removeObserver:self]; [className release]; [super dealloc]; } @end

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  • Flash and Google Maps - Only Last Icon showing

    - by Peter
    I have a simple Map and geocoding sample in Flash using CS4 The problem is simple - I can retrieve a short list from the google search api, but when I try to generate the icons on the map using a loop, only the last icon is displayed. (ignore the house icon, it is generated earlier) I feel I am missing something or made a stupid AS3 mistake (like treating it as if it was c#) - or even a stupid wood-for-the-trees mistake. The problem is in the last line of the code. I have added all my code just in case somebody else can find a use for it - lord knows it took me a great while to figure this out :) It runs here (also, if anybody has an idea why the icon is slightly in the wrong place on render, but corrects if you move the map - please let me know) Any help would be great. Thanks. P import com.google.maps.services.ClientGeocoder; import com.google.maps.services.GeocodingEvent; import com.google.maps.LatLng; import com.google.maps.Map; import com.google.maps.MapEvent; import com.google.maps.MapType; import com.google.maps.overlays.Marker; import com.google.maps.overlays.MarkerOptions; import com.google.maps.styles.FillStyle; import com.google.maps.styles.StrokeStyle; import com.google.maps.controls.* import com.google.maps.overlays.* import flash.display.Bitmap; import flash.display.BitmapData; import com.adobe.utils.StringUtil; import be.boulevart.google.ajaxapi.search.GoogleSearchResult; import be.boulevart.google.events.GoogleApiEvent; import be.boulevart.google.ajaxapi.search.local.GoogleLocalSearch; import be.boulevart.google.ajaxapi.search.local.data.GoogleLocalSearchItem; var strZip:String = new String(); strZip="60661"; var strAddress:String = new String(); strAddress ="100 W. Jackson Blvd, chicago, IL 60661"; var IconArray:Array = new Array; var SearchArray:Array = new Array; /*-------------------------------------------------------------- // The returned search data gets placed into this array ---------------------------------------------------------------*/ var LocalInfo:Array = new Array(); var intCount:int = new int; var intMapReady:int=0; /*=================================================================================== We load the map first and then get the search criteria - this will keep the order of operation clean. The ====================================================================================*/ var map:Map = new Map(); map.key = "ABQIAAAAHwSPp7Lhew456ffD6qa2WmxT_VwdLJEfmcCgytxKjcH1jLKkiihQtfC- TbcwryvBQYhRwHWa8F_Gp9Q"; map.setSize(new Point(600, 550)); map.addEventListener(MapEvent.MAP_READY, onMapReady); //Places the map on the page this.addChild(map); map.x=5; map.y=5; function onMapReady(event:Event):void { //Center the map and place the house marker doGeocode(); } /*========================================================================== Goecode to return the LAT and LONG for the specific address, center the map and add the house icon ===========================================================================*/ function doGeocode() { var geocoder:ClientGeocoder = new ClientGeocoder(); geocoder.addEventListener(GeocodingEvent.GEOCODING_SUCCESS, function(event:GeocodingEvent):void { var objPlacemarks:Array = event.response.placemarks; if (objPlacemarks.length > 0) { map.setCenter(objPlacemarks[0].point, 14, MapType.NORMAL_MAP_TYPE); var request:URLRequest = new URLRequest("house.png"); var imageLoader:Loader = new Loader(); imageLoader.load(request); var objMarkerOptions:MarkerOptions = new MarkerOptions(); objMarkerOptions.icon=imageLoader; objMarkerOptions.icon.scaleX=.15; objMarkerOptions.icon.scaleY=.15; objMarkerOptions.iconAlignment = MarkerOptions.ALIGN_HORIZONTAL_CENTER + MarkerOptions.ALIGN_VERTICAL_CENTER; var objMarker:Marker = new Marker(objPlacemarks[0].point, objMarkerOptions); map.addOverlay(objMarker); doLoadSearch() } }); //Failure code - good practice, really geocoder.addEventListener(GeocodingEvent.GEOCODING_FAILURE, function(event:GeocodingEvent):void { txtResult.appendText("Geocoding failed"); }); // generate geocode geocoder.geocode(strAddress); } /*=============================================================== XML Loader - loads icon file and search text pair from xml file =================================================================*/ function doLoadSearch() { var xmlLoader:URLLoader = new URLLoader(); var xmlData:XML = new XML(); xmlLoader.addEventListener(Event.COMPLETE, LoadXML); xmlLoader.load(new URLRequest("config.xml")); function LoadXML(e:Event):void { xmlData = new XML(e.target.data); RetrieveSearch(); } function RetrieveSearch() { //extract the MapData subset var xmlSearch = xmlData.MapData; // push this to an xml list object var xmlChildren:XMLList = xmlSearch.children(); //loop the list and extract the data into an //array of formatted search criteria for each (var Search:XML in xmlChildren) { txtResult.appendText("Searching For: "+Search.Criteria+" Icon=" + Search.Icon+ "Zip=" + strZip +"\r\n\r\n"); //retrieve search criteria loadLocalInfo(Search.Criteria,Search.Icon,strZip); } } } /*================================================================================== Search Functionality - does a google API search and loads the lats and longs required to place the icons on the map - THIS WILL NOT RUN LOCALLY ===================================================================================*/ function loadLocalInfo(strSearch,strIcon,strZip) { var objLocal:GoogleLocalSearch=new GoogleLocalSearch() objLocal.search(strSearch+" "+strZip,0,"0,0","","") objLocal.addEventListener(GoogleApiEvent.LOCAL_SEARCH_RESULT,onSearchComplete) function onSearchComplete(e:GoogleApiEvent):void { var resulta:GoogleSearchResult=e.data as GoogleSearchResult; //------------------------------------------------ // Load the icon for this particular search //------------------------------------------------ var request:URLRequest = new URLRequest(strIcon); var imageLoader:Loader = new Loader(); imageLoader.load(request); //------------------------------------------------------------- // For test purposes txtResult.appendText("Result Count for "+strSearch+" = "+e.data.results.length+"\r\n\r\n"); for each (var result:GoogleLocalSearchItem in e.data.results as Array) { LocalInfo[intCount]=[String(result.title),strIcon,String(result.latitude),String(result.longitude)]; //--------------------------------------- // Pop the icon onto the map //--------------------------------------- var objLatLng:LatLng = new LatLng(parseFloat(result.latitude), parseFloat(result.longitude)); var objMarkerOptions:MarkerOptions = new MarkerOptions(); objMarkerOptions.icon=imageLoader; objMarkerOptions.hasShadow=false; objMarkerOptions.iconAlignment = MarkerOptions.ALIGN_HORIZONTAL_CENTER + MarkerOptions.ALIGN_VERTICAL_CENTER; var objMarker:Marker = new Marker(objLatLng, objMarkerOptions); /********************************************************** *Everything* works to here - I have traced out execution and all variables. It only works on the last item in the array :( ***********************************************************/ map.addOverlay(objMarker); } } }

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  • Parse XML document

    - by Neil
    I am trying to parse a remote XML document (from Amazon AWS): <ItemLookupResponse xmlns="http://webservices.amazon.com/AWSECommerceService/2009-03-31"> <OperationRequest> <RequestId>011d32c5-4fab-4c7d-8785-ac48b9bda6da</RequestId> <Arguments> <Argument Name="Condition" Value="New"></Argument> <Argument Name="Operation" Value="ItemLookup"></Argument> <Argument Name="Service" Value="AWSECommerceService"></Argument> <Argument Name="Signature" Value="73l8oLJhITTsWtHxsdrS3BMKsdf01n37PE8u/XCbsJM="></Argument> <Argument Name="MerchantId" Value="Amazon"></Argument> <Argument Name="Version" Value="2009-03-31"></Argument> <Argument Name="ItemId" Value="603084260089"></Argument> <Argument Name="IdType" Value="UPC"></Argument> <Argument Name="AWSAccessKeyId" Value="[myAccessKey]"></Argument> <Argument Name="Timestamp" Value="2010-06-14T15:03:27Z"></Argument> <Argument Name="ResponseGroup" Value="OfferSummary,ItemAttributes"></Argument> <Argument Name="SearchIndex" Value="All"></Argument> </Arguments> <RequestProcessingTime>0.0318510000000000</RequestProcessingTime> </OperationRequest> <Items> <Request> <IsValid>True</IsValid> <ItemLookupRequest> <Condition>New</Condition> <DeliveryMethod>Ship</DeliveryMethod> <IdType>UPC</IdType> <MerchantId>Amazon</MerchantId> <OfferPage>1</OfferPage> <ItemId>603084260089</ItemId> <ResponseGroup>OfferSummary</ResponseGroup> <ResponseGroup>ItemAttributes</ResponseGroup> <ReviewPage>1</ReviewPage> <ReviewSort>-SubmissionDate</ReviewSort> <SearchIndex>All</SearchIndex> <VariationPage>All</VariationPage> </ItemLookupRequest> </Request> <Item> <ASIN>B0000UTUNI</ASIN> <DetailPageURL>http://www.amazon.com/Garnier-Fructis-Fortifying-Conditioner-Minute/dp/B0000UTUNI%3FSubscriptionId%3DAKIAIYPTKHCWTRWWPWBQ%26tag%3Dws%26linkCode%3Dxm2%26camp%3D2025%26creative%3D165953%26creativeASIN%3DB0000UTUNI</DetailPageURL> <ItemLinks> <ItemLink> <Description>Technical Details</Description> <URL>http://www.amazon.com/Garnier-Fructis-Fortifying-Conditioner-Minute/dp/tech-data/B0000UTUNI%3FSubscriptionId%3DAKIAIYPTKHCWTRWWPWBQ%26tag%3Dws%26linkCode%3Dxm2%26camp%3D2025%26creative%3D386001%26creativeASIN%3DB0000UTUNI</URL> </ItemLink> <ItemLink> <Description>Add To Baby Registry</Description> <URL>http://www.amazon.com/gp/registry/baby/add-item.html%3Fasin.0%3DB0000UTUNI%26SubscriptionId%3DAKIAIYPTKHCWTRWWPWBQ%26tag%3Dws%26linkCode%3Dxm2%26camp%3D2025%26creative%3D386001%26creativeASIN%3DB0000UTUNI</URL> </ItemLink> <ItemLink> <Description>Add To Wedding Registry</Description> <URL>http://www.amazon.com/gp/registry/wedding/add-item.html%3Fasin.0%3DB0000UTUNI%26SubscriptionId%3DAKIAIYPTKHCWTRWWPWBQ%26tag%3Dws%26linkCode%3Dxm2%26camp%3D2025%26creative%3D386001%26creativeASIN%3DB0000UTUNI</URL> </ItemLink> <ItemLink> <Description>Add To Wishlist</Description> <URL>http://www.amazon.com/gp/registry/wishlist/add-item.html%3Fasin.0%3DB0000UTUNI%26SubscriptionId%3DAKIAIYPTKHCWTRWWPWBQ%26tag%3Dws%26linkCode%3Dxm2%26camp%3D2025%26creative%3D386001%26creativeASIN%3DB0000UTUNI</URL> </ItemLink> <ItemLink> <Description>Tell A Friend</Description> <URL>http://www.amazon.com/gp/pdp/taf/B0000UTUNI%3FSubscriptionId%3DAKIAIYPTKHCWTRWWPWBQ%26tag%3Dws%26linkCode%3Dxm2%26camp%3D2025%26creative%3D386001%26creativeASIN%3DB0000UTUNI</URL> </ItemLink> <ItemLink> <Description>All Customer Reviews</Description> <URL>http://www.amazon.com/review/product/B0000UTUNI%3FSubscriptionId%3DAKIAIYPTKHCWTRWWPWBQ%26tag%3Dws%26linkCode%3Dxm2%26camp%3D2025%26creative%3D386001%26creativeASIN%3DB0000UTUNI</URL> </ItemLink> <ItemLink> <Description>All Offers</Description> <URL>http://www.amazon.com/gp/offer-listing/B0000UTUNI%3FSubscriptionId%3DAKIAIYPTKHCWTRWWPWBQ%26tag%3Dws%26linkCode%3Dxm2%26camp%3D2025%26creative%3D386001%26creativeASIN%3DB0000UTUNI</URL> </ItemLink> </ItemLinks> <ItemAttributes> <Binding>Health and Beauty</Binding> <Brand>Garnier</Brand> <EAN>0603084260089</EAN> <Feature>Helps restore strength and shine</Feature> <Feature>Penetrates deep to nourish, repair and rejuvenate</Feature> <Feature>Makes hair softer and more manageable without weighing it down</Feature> <ItemDimensions> <Weight Units="hundredths-pounds">40</Weight> </ItemDimensions> <Label>Garnier</Label> <ListPrice> <Amount>419</Amount> <CurrencyCode>USD</CurrencyCode> <FormattedPrice>$4.19</FormattedPrice> </ListPrice> <Manufacturer>Garnier</Manufacturer> <NumberOfItems>1</NumberOfItems> <ProductGroup>Health and Beauty</ProductGroup> <ProductTypeName>ABIS_DRUGSTORE</ProductTypeName> <Publisher>Garnier</Publisher> <Size>5.0 oz</Size> <Studio>Garnier</Studio> <Title>Garnier Fructis Fortifying Fortifying Deep Conditioner, 3 Minute Masque - 5 oz</Title> <UPC>603084260089</UPC> </ItemAttributes> <OfferSummary> <LowestNewPrice> <Amount>229</Amount> <CurrencyCode>USD</CurrencyCode> <FormattedPrice>$2.29</FormattedPrice> </LowestNewPrice> <TotalNew>7</TotalNew> <TotalUsed>0</TotalUsed> <TotalCollectible>0</TotalCollectible> <TotalRefurbished>0</TotalRefurbished> </OfferSummary> </Item> </Items> </ItemLookupResponse> I am trying to extract data from the XML stream using XPathDocument, but with no luck: WebRequest request = HttpWebRequest.Create(url); WebResponse response = request.GetResponse(); //XmlDocument doc = new XmlDocument(); XPathDocument Doc = new XPathDocument(response.GetResponseStream()); XPathNavigator nav = Doc.CreateNavigator(); XPathNodeIterator ListPrice = nav.Select("/ItemLookupResponse/Items/Item/ItemAttributes/ListPrice"); foreach (XPathNavigator node in ListPrice) { Response.Write(node.GetAttribute("Amount", NAMESPACE)); } What am I missing? Thanks in advance!!

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  • Changing the action of a form with javascript/jquery

    - by Micah
    I'm having an issue that is driving me crazy. I'm trying to modify the openid-selector to support facebook. I'm using RPXNow as my provider so it requires the form to be submitted to a different url than the standard. For example. RpxNow requires me to setup my form like this: <form action="https://wikipediamaze.rpxnow.com/openid/start?token_url=..."> This works for every provider except for facebook and myspace. Those require the form to be posted to a different url like this: <form action="https://wikipediamaze.rpxnow.com/facebook/start?token_url=..."> and <form action="https://wikipediamaze.rpxnow.com/myspace/start?token_url=..."> The open id selector has a bunch of buttons on the form each representing the openid providers. What I'm trying to do is detect when the facebook or myspace button is clicked and changed the action on the form before submitting. However it's not working. Here is my code. I've tried several variations all with the same "not supported" exception $("#openid_form").attr("action", form_url) document.forms[0].action = form_url Any suggestions? Update Here are more details on the code. I've ommitted some for brevity. The only thing i've done is added the facebook section to the "providers_large" object (which successfully adds the logo to the website), and instead of supply a url identifying the user, I'm creating a property called "form_url" which is what I want to set the action of my form to. If you look at the section title "Provider image click" you'll see where I'm checking for the presence of the property "form_url" and using jquery to change the action and submit the form. However when I step through the javascript in debug mode it tells me it's an ivalid operation. var providers_large = { google: { name: 'Google', url: 'https://www.google.com/accounts/o8/id' }, facebook: { name: 'Facebook', form_url: 'http://wikipediamaze.rpxnow.com/facebook/start?token_url=http://www.wikipediamaze.com/Accounts/Logon' }, }; var providers_small = { myopenid: { name: 'MyOpenID', label: 'Enter your MyOpenID username.', url: 'http://{username}.myopenid.com/' }, livejournal: { name: 'LiveJournal', label: 'Enter your Livejournal username.', url: 'http://{username}.livejournal.com/' }, flickr: { name: 'Flickr', label: 'Enter your Flickr username.', url: 'http://flickr.com/{username}/' }, technorati: { name: 'Technorati', label: 'Enter your Technorati username.', url: 'http://technorati.com/people/technorati/{username}/' }, wordpress: { name: 'Wordpress', label: 'Enter your Wordpress.com username.', url: 'http://{username}.wordpress.com/' }, blogger: { name: 'Blogger', label: 'Your Blogger account', url: 'http://{username}.blogspot.com/' }, verisign: { name: 'Verisign', label: 'Your Verisign username', url: 'http://{username}.pip.verisignlabs.com/' }, vidoop: { name: 'Vidoop', label: 'Your Vidoop username', url: 'http://{username}.myvidoop.com/' }, verisign: { name: 'Verisign', label: 'Your Verisign username', url: 'http://{username}.pip.verisignlabs.com/' }, claimid: { name: 'ClaimID', label: 'Your ClaimID username', url: 'http://claimid.com/{username}' } }; var providers = $.extend({}, providers_large, providers_small); var openid = { cookie_expires: 6*30, // 6 months. cookie_name: 'openid_provider', cookie_path: '/', img_path: 'images/', input_id: null, provider_url: null, init: function(input_id) { var openid_btns = $('#openid_btns'); this.input_id = input_id; $('#openid_choice').show(); $('#openid_input_area').empty(); // add box for each provider for (id in providers_large) { openid_btns.append(this.getBoxHTML(providers_large[id], 'large', '.gif')); } if (providers_small) { openid_btns.append('<br/>'); for (id in providers_small) { openid_btns.append(this.getBoxHTML(providers_small[id], 'small', '.ico')); } } $('#openid_form').submit(this.submit); var box_id = this.readCookie(); if (box_id) { this.signin(box_id, true); } }, getBoxHTML: function(provider, box_size, image_ext) { var box_id = provider["name"].toLowerCase(); return '<a title="'+provider["name"]+'" href="javascript: openid.signin(\''+ box_id +'\');"' + ' style="background: #FFF url(' + this.img_path + box_id + image_ext+') no-repeat center center" ' + 'class="' + box_id + ' openid_' + box_size + '_btn"></a>'; }, /* Provider image click */ signin: function(box_id, onload) { var provider = providers[box_id]; if (! provider) { return; } this.highlight(box_id); this.setCookie(box_id); // prompt user for input? if (provider['label']) { this.useInputBox(provider); this.provider_url = provider['url']; } else if(provider['form_url']) { $('#openid_form').attr("action", provider['form_url']); $('#openid_form').submit(); } else { this.setOpenIdUrl(provider['url']); if (! onload) { $('#openid_form').submit(); } } }, /* Sign-in button click */ submit: function() { var url = openid.provider_url; if (url) { url = url.replace('{username}', $('#openid_username').val()); openid.setOpenIdUrl(url); } return true; }, setOpenIdUrl: function (url) { var hidden = $('#'+this.input_id); if (hidden.length > 0) { hidden.value = url; } else { $('#openid_form').append('<input type="hidden" id="' + this.input_id + '" name="' + this.input_id + '" value="'+url+'"/>'); } }, highlight: function (box_id) { // remove previous highlight. var highlight = $('#openid_highlight'); if (highlight) { highlight.replaceWith($('#openid_highlight a')[0]); } // add new highlight. $('.'+box_id).wrap('<div id="openid_highlight"></div>'); }, setCookie: function (value) { var date = new Date(); date.setTime(date.getTime()+(this.cookie_expires*24*60*60*1000)); var expires = "; expires="+date.toGMTString(); document.cookie = this.cookie_name+"="+value+expires+"; path=" + this.cookie_path; }, readCookie: function () { var nameEQ = this.cookie_name + "="; var ca = document.cookie.split(';'); for(var i=0;i < ca.length;i++) { var c = ca[i]; while (c.charAt(0)==' ') c = c.substring(1,c.length); if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length); } return null; }, useInputBox: function (provider) { var input_area = $('#openid_input_area'); var html = ''; var id = 'openid_username'; var value = ''; var label = provider['label']; var style = ''; if (label) { html = '<p>' + label + '</p>'; } if (provider['name'] == 'OpenID') { id = this.input_id; value = 'http://'; style = 'background:#FFF url('+this.img_path+'openid-inputicon.gif) no-repeat scroll 0 50%; padding-left:18px;'; } html += '<input id="'+id+'" type="text" style="'+style+'" name="'+id+'" value="'+value+'" />' + '<input id="openid_submit" type="submit" value="Sign-In"/>'; input_area.empty(); input_area.append(html); $('#'+id).focus(); } };

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  • Handling inheritance with overriding efficiently

    - by Fyodor Soikin
    I have the following two data structures. First, a list of properties applied to object triples: Object1 Object2 Object3 Property Value O1 O2 O3 P1 "abc" O1 O2 O3 P2 "xyz" O1 O3 O4 P1 "123" O2 O4 O5 P1 "098" Second, an inheritance tree: O1 O2 O4 O3 O5 Or viewed as a relation: Object Parent O2 O1 O4 O2 O3 O1 O5 O3 O1 null The semantics of this being that O2 inherits properties from O1; O4 - from O2 and O1; O3 - from O1; and O5 - from O3 and O1, in that order of precedence. NOTE 1: I have an efficient way to select all children or all parents of a given object. This is currently implemented with left and right indexes, but hierarchyid could also work. This does not seem important right now. NOTE 2: I have tiggers in place that make sure that the "Object" column always contains all possible objects, even when they do not really have to be there (i.e. have no parent or children defined). This makes it possible to use inner joins rather than severely less effiecient outer joins. The objective is: Given a pair of (Property, Value), return all object triples that have that property with that value either defined explicitly or inherited from a parent. NOTE 1: An object triple (X,Y,Z) is considered a "parent" of triple (A,B,C) when it is true that either X = A or X is a parent of A, and the same is true for (Y,B) and (Z,C). NOTE 2: A property defined on a closer parent "overrides" the same property defined on a more distant parent. NOTE 3: When (A,B,C) has two parents - (X1,Y1,Z1) and (X2,Y2,Z2), then (X1,Y1,Z1) is considered a "closer" parent when: (a) X2 is a parent of X1, or (b) X2 = X1 and Y2 is a parent of Y1, or (c) X2 = X1 and Y2 = Y1 and Z2 is a parent of Z1 In other words, the "closeness" in ancestry for triples is defined based on the first components of the triples first, then on the second components, then on the third components. This rule establishes an unambigous partial order for triples in terms of ancestry. For example, given the pair of (P1, "abc"), the result set of triples will be: O1, O2, O3 -- Defined explicitly O1, O2, O5 -- Because O5 inherits from O3 O1, O4, O3 -- Because O4 inherits from O2 O1, O4, O5 -- Because O4 inherits from O2 and O5 inherits from O3 O2, O2, O3 -- Because O2 inherits from O1 O2, O2, O5 -- Because O2 inherits from O1 and O5 inherits from O3 O2, O4, O3 -- Because O2 inherits from O1 and O4 inherits from O2 O3, O2, O3 -- Because O3 inherits from O1 O3, O2, O5 -- Because O3 inherits from O1 and O5 inherits from O3 O3, O4, O3 -- Because O3 inherits from O1 and O4 inherits from O2 O3, O4, O5 -- Because O3 inherits from O1 and O4 inherits from O2 and O5 inherits from O3 O4, O2, O3 -- Because O4 inherits from O1 O4, O2, O5 -- Because O4 inherits from O1 and O5 inherits from O3 O4, O4, O3 -- Because O4 inherits from O1 and O4 inherits from O2 O5, O2, O3 -- Because O5 inherits from O1 O5, O2, O5 -- Because O5 inherits from O1 and O5 inherits from O3 O5, O4, O3 -- Because O5 inherits from O1 and O4 inherits from O2 O5, O4, O5 -- Because O5 inherits from O1 and O4 inherits from O2 and O5 inherits from O3 Note that the triple (O2, O4, O5) is absent from this list. This is because property P1 is defined explicitly for the triple (O2, O4, O5) and this prevents that triple from inheriting that property from (O1, O2, O3). Also note that the triple (O4, O4, O5) is also absent. This is because that triple inherits its value of P1="098" from (O2, O4, O5), because it is a closer parent than (O1, O2, O3). The straightforward way to do it is the following. First, for every triple that a property is defined on, select all possible child triples: select Children1.Id as O1, Children2.Id as O2, Children3.Id as O3, tp.Property, tp.Value from TriplesAndProperties tp -- Select corresponding objects of the triple inner join Objects as Objects1 on Objects1.Id = tp.O1 inner join Objects as Objects2 on Objects2.Id = tp.O2 inner join Objects as Objects3 on Objects3.Id = tp.O3 -- Then add all possible children of all those objects inner join Objects as Children1 on Objects1.Id [isparentof] Children1.Id inner join Objects as Children2 on Objects2.Id [isparentof] Children2.Id inner join Objects as Children3 on Objects3.Id [isparentof] Children3.Id But this is not the whole story: if some triple inherits the same property from several parents, this query will yield conflicting results. Therefore, second step is to select just one of those conflicting results: select * from ( select Children1.Id as O1, Children2.Id as O2, Children3.Id as O3, tp.Property, tp.Value, row_number() over( partition by Children1.Id, Children2.Id, Children3.Id, tp.Property order by Objects1.[depthInTheTree] descending, Objects2.[depthInTheTree] descending, Objects3.[depthInTheTree] descending ) as InheritancePriority from ... (see above) ) where InheritancePriority = 1 The window function row_number() over( ... ) does the following: for every unique combination of objects triple and property, it sorts all values by the ancestral distance from the triple to the parents that the value is inherited from, and then I only select the very first of the resulting list of values. A similar effect can be achieved with a GROUP BY and ORDER BY statements, but I just find the window function semantically cleaner (the execution plans they yield are identical). The point is, I need to select the closest of contributing ancestors, and for that I need to group and then sort within the group. And finally, now I can simply filter the result set by Property and Value. This scheme works. Very reliably and predictably. It has proven to be very powerful for the business task it implements. The only trouble is, it is awfuly slow. One might point out the join of seven tables might be slowing things down, but that is actually not the bottleneck. According to the actual execution plan I'm getting from the SQL Management Studio (as well as SQL Profiler), the bottleneck is the sorting. The problem is, in order to satisfy my window function, the server has to sort by Children1.Id, Children2.Id, Children3.Id, tp.Property, Parents1.[depthInTheTree] descending, Parents2.[depthInTheTree] descending, Parents3.[depthInTheTree] descending, and there can be no indexes it can use, because the values come from a cross join of several tables. EDIT: Per Michael Buen's suggestion (thank you, Michael), I have posted the whole puzzle to sqlfiddle here. One can see in the execution plan that the Sort operation accounts for 32% of the whole query, and that is going to grow with the number of total rows, because all the other operations use indexes. Usually in such cases I would use an indexed view, but not in this case, because indexed views cannot contain self-joins, of which there are six. The only way that I can think of so far is to create six copies of the Objects table and then use them for the joins, thus enabling an indexed view. Did the time come that I shall be reduced to that kind of hacks? The despair sets in.

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  • c# Unable to open file for reading

    - by Maks
    I'm writing a program that uses FileSystemWatcher to monitor changes to a given directory, and when it recieves OnCreated or OnChanged event, it copies those created/changed files to a specified directorie(s). At first I had problems with the fact that OnChanged/OnCreated events can be sent twice (not acceptable in case it needed to process 500MB file) but I made a way around this and with what I'm REALLY STUCKED with is getting the following IOException: The process cannot access the file 'C:\Where are Photos\bookmarks (11).html' because it is being used by another process. Thus, preventing the program from copying all the files it should. So as I mentioned, when user uses this program he/she specifes monitored directory, when user copies/creates/changes file in that directory, program should get OnCreated/OnChanged event and then copy that file to few other directories. Above error happens in all casess, if user copies few files that needs to owerwrite other ones in folder being monitored or when copying bulk of several files or even sometimes when copying one file in a monitored directory. Whole program is quite big so I'm sending the most important parts. OnCreated: private void OnCreated(object source, FileSystemEventArgs e) { AddLogEntry(e.FullPath, "created", ""); // Update last access data if it's file so the same file doesn't // get processed twice because of sending another event. if (fileType(e.FullPath) == 2) { lastPath = e.FullPath; lastTime = DateTime.Now; } // serves no purpose now, it will be remove soon string fileName = GetFileName(e.FullPath); // copies file from source to few other directories Copy(e.FullPath, fileName); Console.WriteLine("OnCreated: " + e.FullPath); } OnChanged: private void OnChanged(object source, FileSystemEventArgs e) { // is it directory if (fileType(e.FullPath) == 1) return; // don't mind directory changes itself // Only if enough time has passed or if it's some other file // because two events can be generated int timeDiff = ((TimeSpan)(DateTime.Now - lastTime)).Seconds; if ((timeDiff < minSecsDiff) && (e.FullPath.Equals(lastPath))) { Console.WriteLine("-- skipped -- {0}, timediff: {1}", e.FullPath, timeDiff); return; } // Update last access data for above to work lastPath = e.FullPath; lastTime = DateTime.Now; // Only if size is changed, the rest will handle other handlers if (e.ChangeType == WatcherChangeTypes.Changed) { AddLogEntry(e.FullPath, "changed", ""); string fileName = GetFileName(e.FullPath); Copy(e.FullPath, fileName); Console.WriteLine("OnChanged: " + e.FullPath); } } fileType: private int fileType(string path) { if (Directory.Exists(path)) return 1; // directory else if (File.Exists(path)) return 2; // file else return 0; } Copy: private void Copy(string srcPath, string fileName) { foreach (string dstDirectoy in paths) { string eventType = "copied"; string error = "noerror"; string path = ""; string dirPortion = ""; // in case directory needs to be made if (srcPath.Length > fsw.Path.Length) { path = srcPath.Substring(fsw.Path.Length, srcPath.Length - fsw.Path.Length); int pos = path.LastIndexOf('\\'); if (pos != -1) dirPortion = path.Substring(0, pos); } if (fileType(srcPath) == 1) { try { Directory.CreateDirectory(dstDirectoy + path); //Directory.CreateDirectory(dstDirectoy + fileName); eventType = "created"; } catch (IOException e) { eventType = "error"; error = e.Message; } } else { try { if (!overwriteFile && File.Exists(dstDirectoy + path)) continue; // create new dir anyway even if it exists just to be sure Directory.CreateDirectory(dstDirectoy + dirPortion); // copy file from where event occured to all specified directories using (FileStream fsin = new FileStream(srcPath, FileMode.Open, FileAccess.Read, FileShare.Read)) { using (FileStream fsout = new FileStream(dstDirectoy + path, FileMode.Create, FileAccess.Write)) { byte[] buffer = new byte[32768]; int bytesRead = -1; while ((bytesRead = fsin.Read(buffer, 0, buffer.Length)) > 0) fsout.Write(buffer, 0, bytesRead); } } } catch (Exception e) { if ((e is IOException) && (overwriteFile == false)) { eventType = "skipped"; } else { eventType = "error"; error = e.Message; // attempt to find and kill the process locking the file. // failed, miserably System.Diagnostics.Process tool = new System.Diagnostics.Process(); tool.StartInfo.FileName = "handle.exe"; tool.StartInfo.Arguments = "\"" + srcPath + "\""; tool.StartInfo.UseShellExecute = false; tool.StartInfo.RedirectStandardOutput = true; tool.Start(); tool.WaitForExit(); string outputTool = tool.StandardOutput.ReadToEnd(); string matchPattern = @"(?<=\s+pid:\s+)\b(\d+)\b(?=\s+)"; foreach (Match match in Regex.Matches(outputTool, matchPattern)) { System.Diagnostics.Process.GetProcessById(int.Parse(match.Value)).Kill(); } Console.WriteLine("ERROR: {0}: [ {1} ]", e.Message, srcPath); } } } AddLogEntry(dstDirectoy + path, eventType, error); } } I checked everywhere in my program and whenever I use some file I use it in using block so even writing event to log (class for what I ommited since there is probably too much code already in post) wont lock the file, that is it shouldn't since all operations are using using statement block. I simply have no clue who's locking the file if not my program "copy" process from user through Windows or something else. Right now I have two possible "solutions" (I can't say they are clean solutions since they are hacks and as such not desireable). Since probably the problem is with fileType method (what else could lock the file?) I tried changing it to this, to simulate "blocking-until-ready-to-open" operation: fileType: private int fileType(string path) { FileStream fs = null; int ret = 0; bool run = true; if (Directory.Exists(path)) ret = 1; else { while (run) { try { fs = new FileStream(path, FileMode.Open); ret = 2; run = false; } catch (IOException) { } finally { if (fs != null) { fs.Close(); fs.Dispose(); } } } } return ret; } This is working as much as I could tell (test), but... it's hack, not to mention other deficients. The other "solution" I could try (I didn't test it yet) is using GC.Collect() somewhere at the end of fileType() method. Maybe even worse "solution" than previous one. Can someone pleas tell me, what on earth is locking the file, preventing it from opening and how can I fix that? What am I missing to see? Thanks in advance.

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  • A free standing ASP.NET Pager Web Control

    - by Rick Strahl
    Paging in ASP.NET has been relatively easy with stock controls supporting basic paging functionality. However, recently I built an MVC application and one of the things I ran into was that I HAD TO build manual paging support into a few of my pages. Dealing with list controls and rendering markup is easy enough, but doing paging is a little more involved. I ended up with a small but flexible component that can be dropped anywhere. As it turns out the task of creating a semi-generic Pager control for MVC was fairly easily. Now I’m back to working in Web Forms and thought to myself that the way I created the pager in MVC actually would also work in ASP.NET – in fact quite a bit easier since the whole thing can be conveniently wrapped up into an easily reusable control. A standalone pager would provider easier reuse in various pages and a more consistent pager display regardless of what kind of 'control’ the pager is associated with. Why a Pager Control? At first blush it might sound silly to create a new pager control – after all Web Forms has pretty decent paging support, doesn’t it? Well, sort of. Yes the GridView control has automatic paging built in and the ListView control has the related DataPager control. The built in ASP.NET paging has several issues though: Postback and JavaScript requirements If you look at paging links in ASP.NET they are always postback links with javascript:__doPostback() calls that go back to the server. While that works fine and actually has some benefit like the fact that paging saves changes to the page and post them back, it’s not very SEO friendly. Basically if you use javascript based navigation nosearch engine will follow the paging links which effectively cuts off list content on the first page. The DataPager control does support GET based links via the QueryStringParameter property, but the control is effectively tied to the ListView control (which is the only control that implements IPageableItemContainer). DataSource Controls required for Efficient Data Paging Retrieval The only way you can get paging to work efficiently where only the few records you display on the page are queried for and retrieved from the database you have to use a DataSource control - only the Linq and Entity DataSource controls  support this natively. While you can retrieve this data yourself manually, there’s no way to just assign the page number and render the pager based on this custom subset. Other than that default paging requires a full resultset for ASP.NET to filter the data and display only a subset which can be very resource intensive and wasteful if you’re dealing with largish resultsets (although I’m a firm believer in returning actually usable sets :-}). If you use your own business layer that doesn’t fit an ObjectDataSource you’re SOL. That’s a real shame too because with LINQ based querying it’s real easy to retrieve a subset of data that is just the data you want to display but the native Pager functionality doesn’t support just setting properties to display just the subset AFAIK. DataPager is not Free Standing The DataPager control is the closest thing to a decent Pager implementation that ASP.NET has, but alas it’s not a free standing component – it works off a related control and the only one that it effectively supports from the stock ASP.NET controls is the ListView control. This means you can’t use the same data pager formatting for a grid and a list view or vice versa and you’re always tied to the control. Paging Events In order to handle paging you have to deal with paging events. The events fire at specific time instances in the page pipeline and because of this you often have to handle data binding in a way to work around the paging events or else end up double binding your data sources based on paging. Yuk. Styling The GridView pager is a royal pain to beat into submission for styled rendering. The DataPager control has many more options and template layout and it renders somewhat cleaner, but it too is not exactly easy to get a decent display for. Not a Generic Solution The problem with the ASP.NET controls too is that it’s not generic. GridView, DataGrid use their own internal paging, ListView can use a DataPager and if you want to manually create data layout – well you’re on your own. IOW, depending on what you use you likely have very different looking Paging experiences. So, I figured I’ve struggled with this once too many and finally sat down and built a Pager control. The Pager Control My goal was to create a totally free standing control that has no dependencies on other controls and certainly no requirements for using DataSource controls. The idea is that you should be able to use this pager control without any sort of data requirements at all – you should just be able to set properties and be able to display a pager. The Pager control I ended up with has the following features: Completely free standing Pager control – no control or data dependencies Complete manual control – Pager can render without any data dependency Easy to use: Only need to set PageSize, ActivePage and TotalItems Supports optional filtering of IQueryable for efficient queries and Pager rendering Supports optional full set filtering of IEnumerable<T> and DataTable Page links are plain HTTP GET href Links Control automatically picks up Page links on the URL and assigns them (automatic page detection no page index changing events to hookup) Full CSS Styling support On the downside there’s no templating support for the control so the layout of the pager is relatively fixed. All elements however are stylable and there are options to control the text, and layout options such as whether to display first and last pages and the previous/next buttons and so on. To give you an idea what the pager looks like, here are two differently styled examples (all via CSS):   The markup for these two pagers looks like this: <ww:Pager runat="server" id="ItemPager" PageSize="5" PageLinkCssClass="gridpagerbutton" SelectedPageCssClass="gridpagerbutton-selected" PagesTextCssClass="gridpagertext" CssClass="gridpager" RenderContainerDiv="true" ContainerDivCssClass="gridpagercontainer" MaxPagesToDisplay="6" PagesText="Item Pages:" NextText="next" PreviousText="previous" /> <ww:Pager runat="server" id="ItemPager2" PageSize="5" RenderContainerDiv="true" MaxPagesToDisplay="6" /> The latter example uses default style settings so it there’s not much to set. The first example on the other hand explicitly assigns custom styles and overrides a few of the formatting options. Styling The styling is based on a number of CSS classes of which the the main pager, pagerbutton and pagerbutton-selected classes are the important ones. Other styles like pagerbutton-next/prev/first/last are based on the pagerbutton style. The default styling shown for the red outlined pager looks like this: .pagercontainer { margin: 20px 0; background: whitesmoke; padding: 5px; } .pager { float: right; font-size: 10pt; text-align: left; } .pagerbutton,.pagerbutton-selected,.pagertext { display: block; float: left; text-align: center; border: solid 2px maroon; min-width: 18px; margin-left: 3px; text-decoration: none; padding: 4px; } .pagerbutton-selected { font-size: 130%; font-weight: bold; color: maroon; border-width: 0px; background: khaki; } .pagerbutton-first { margin-right: 12px; } .pagerbutton-last,.pagerbutton-prev { margin-left: 12px; } .pagertext { border: none; margin-left: 30px; font-weight: bold; } .pagerbutton a { text-decoration: none; } .pagerbutton:hover { background-color: maroon; color: cornsilk; } .pagerbutton-prev { background-image: url(images/prev.png); background-position: 2px center; background-repeat: no-repeat; width: 35px; padding-left: 20px; } .pagerbutton-next { background-image: url(images/next.png); background-position: 40px center; background-repeat: no-repeat; width: 35px; padding-right: 20px; margin-right: 0px; } Yup that’s a lot of styling settings although not all of them are required. The key ones are pagerbutton, pager and pager selection. The others (which are implicitly created by the control based on the pagerbutton style) are for custom markup of the ‘special’ buttons. In my apps I tend to have two kinds of pages: Those that are associated with typical ‘grid’ displays that display purely tabular data and those that have a more looser list like layout. The two pagers shown above represent these two views and the pager and gridpager styles in my standard style sheet reflect these two styles. Configuring the Pager with Code Finally lets look at what it takes to hook up the pager. As mentioned in the highlights the Pager control is completely independent of other controls so if you just want to display a pager on its own it’s as simple as dropping the control and assigning the PageSize, ActivePage and either TotalPages or TotalItems. So for this markup: <ww:Pager runat="server" id="ItemPagerManual" PageSize="5" MaxPagesToDisplay="6" /> I can use code as simple as: ItemPagerManual.PageSize = 3; ItemPagerManual.ActivePage = 4;ItemPagerManual.TotalItems = 20; Note that ActivePage is not required - it will automatically use any Page=x query string value and assign it, although you can override it as I did above. TotalItems can be any value that you retrieve from a result set or manually assign as I did above. A more realistic scenario based on a LINQ to SQL IQueryable result is even easier. In this example, I have a UserControl that contains a ListView control that renders IQueryable data. I use a User Control here because there are different views the user can choose from with each view being a different user control. This incidentally also highlights one of the nice features of the pager: Because the pager is independent of the control I can put the pager on the host page instead of into each of the user controls. IOW, there’s only one Pager control, but there are potentially many user controls/listviews that hold the actual display data. The following code demonstrates how to use the Pager with an IQueryable that loads only the records it displays: protected voidPage_Load(objectsender, EventArgs e) {     Category = Request.Params["Category"] ?? string.Empty;     IQueryable<wws_Item> ItemList = ItemRepository.GetItemsByCategory(Category);     // Update the page and filter the list down     ItemList = ItemPager.FilterIQueryable<wws_Item>(ItemList); // Render user control with a list view Control ulItemList = LoadControl("~/usercontrols/" + App.Configuration.ItemListType + ".ascx"); ((IInventoryItemListControl)ulItemList).InventoryItemList = ItemList; phItemList.Controls.Add(ulItemList); // placeholder } The code uses a business object to retrieve Items by category as an IQueryable which means that the result is only an expression tree that hasn’t execute SQL yet and can be further filtered. I then pass this IQueryable to the FilterIQueryable() helper method of the control which does two main things: Filters the IQueryable to retrieve only the data displayed on the active page Sets the Totaltems property and calculates TotalPages on the Pager and that’s it! When the Pager renders it uses those values, plus the PageSize and ActivePage properties to render the Pager. In addition to IQueryable there are also filter methods for IEnumerable<T> and DataTable, but these versions just filter the data by removing rows/items from the entire already retrieved data. Output Generated and Paging Links The output generated creates pager links as plain href links. Here’s what the output looks like: <div id="ItemPager" class="pagercontainer"> <div class="pager"> <span class="pagertext">Pages: </span><a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=1" class="pagerbutton" />1</a> <a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=2" class="pagerbutton" />2</a> <a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=3" class="pagerbutton" />3</a> <span class="pagerbutton-selected">4</span> <a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=5" class="pagerbutton" />5</a> <a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=6" class="pagerbutton" />6</a> <a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=20" class="pagerbutton pagerbutton-last" />20</a>&nbsp;<a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=3" class="pagerbutton pagerbutton-prev" />Prev</a>&nbsp;<a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=5" class="pagerbutton pagerbutton-next" />Next</a></div> <br clear="all" /> </div> </div> The links point back to the current page and simply append a Page= page link into the page. When the page gets reloaded with the new page number the pager automatically detects the page number and automatically assigns the ActivePage property which results in the appropriate page to be displayed. The code shown in the previous section is all that’s needed to handle paging. Note that HTTP GET based paging is different than the Postback paging ASP.NET uses by default. Postback paging preserves modified page content when clicking on pager buttons, but this control will simply load a new page – no page preservation at this time. The advantage of not using Postback paging is that the URLs generated are plain HTML links that a search engine can follow where __doPostback() links are not. Pager with a Grid The pager also works in combination with grid controls so it’s easy to bypass the grid control’s paging features if desired. In the following example I use a gridView control and binds it to a DataTable result which is also filterable by the Pager control. The very basic plain vanilla ASP.NET grid markup looks like this: <div style="width: 600px; margin: 0 auto;padding: 20px; "> <asp:DataGrid runat="server" AutoGenerateColumns="True" ID="gdItems" CssClass="blackborder" style="width: 600px;"> <AlternatingItemStyle CssClass="gridalternate" /> <HeaderStyle CssClass="gridheader" /> </asp:DataGrid> <ww:Pager runat="server" ID="Pager" CssClass="gridpager" ContainerDivCssClass="gridpagercontainer" PageLinkCssClass="gridpagerbutton" SelectedPageCssClass="gridpagerbutton-selected" PageSize="8" RenderContainerDiv="true" MaxPagesToDisplay="6" /> </div> and looks like this when rendered: using custom set of CSS styles. The code behind for this code is also very simple: protected void Page_Load(object sender, EventArgs e) { string category = Request.Params["category"] ?? ""; busItem itemRep = WebStoreFactory.GetItem(); var items = itemRep.GetItemsByCategory(category) .Select(itm => new {Sku = itm.Sku, Description = itm.Description}); // run query into a DataTable for demonstration DataTable dt = itemRep.Converter.ToDataTable(items,"TItems"); // Remove all items not on the current page dt = Pager.FilterDataTable(dt,0); // bind and display gdItems.DataSource = dt; gdItems.DataBind(); } A little contrived I suppose since the list could already be bound from the list of elements, but this is to demonstrate that you can also bind against a DataTable if your business layer returns those. Unfortunately there’s no way to filter a DataReader as it’s a one way forward only reader and the reader is required by the DataSource to perform the bindings.  However, you can still use a DataReader as long as your business logic filters the data prior to rendering and provides a total item count (most likely as a second query). Control Creation The control itself is a pretty brute force ASP.NET control. Nothing clever about this other than some basic rendering logic and some simple calculations and update routines to determine which buttons need to be shown. You can take a look at the full code from the West Wind Web Toolkit’s Repository (note there are a few dependencies). To give you an idea how the control works here is the Render() method: /// <summary> /// overridden to handle custom pager rendering for runtime and design time /// </summary> /// <param name="writer"></param> protected override void Render(HtmlTextWriter writer) { base.Render(writer); if (TotalPages == 0 && TotalItems > 0) TotalPages = CalculateTotalPagesFromTotalItems(); if (DesignMode) TotalPages = 10; // don't render pager if there's only one page if (TotalPages < 2) return; if (RenderContainerDiv) { if (!string.IsNullOrEmpty(ContainerDivCssClass)) writer.AddAttribute("class", ContainerDivCssClass); writer.RenderBeginTag("div"); } // main pager wrapper writer.WriteBeginTag("div"); writer.AddAttribute("id", this.ClientID); if (!string.IsNullOrEmpty(CssClass)) writer.WriteAttribute("class", this.CssClass); writer.Write(HtmlTextWriter.TagRightChar + "\r\n"); // Pages Text writer.WriteBeginTag("span"); if (!string.IsNullOrEmpty(PagesTextCssClass)) writer.WriteAttribute("class", PagesTextCssClass); writer.Write(HtmlTextWriter.TagRightChar); writer.Write(this.PagesText); writer.WriteEndTag("span"); // if the base url is empty use the current URL FixupBaseUrl(); // set _startPage and _endPage ConfigurePagesToRender(); // write out first page link if (ShowFirstAndLastPageLinks && _startPage != 1) { writer.WriteBeginTag("a"); string pageUrl = StringUtils.SetUrlEncodedKey(BaseUrl, QueryStringPageField, (1).ToString()); writer.WriteAttribute("href", pageUrl); if (!string.IsNullOrEmpty(PageLinkCssClass)) writer.WriteAttribute("class", PageLinkCssClass + " " + PageLinkCssClass + "-first"); writer.Write(HtmlTextWriter.SelfClosingTagEnd); writer.Write("1"); writer.WriteEndTag("a"); writer.Write("&nbsp;"); } // write out all the page links for (int i = _startPage; i < _endPage + 1; i++) { if (i == ActivePage) { writer.WriteBeginTag("span"); if (!string.IsNullOrEmpty(SelectedPageCssClass)) writer.WriteAttribute("class", SelectedPageCssClass); writer.Write(HtmlTextWriter.TagRightChar); writer.Write(i.ToString()); writer.WriteEndTag("span"); } else { writer.WriteBeginTag("a"); string pageUrl = StringUtils.SetUrlEncodedKey(BaseUrl, QueryStringPageField, i.ToString()).TrimEnd('&'); writer.WriteAttribute("href", pageUrl); if (!string.IsNullOrEmpty(PageLinkCssClass)) writer.WriteAttribute("class", PageLinkCssClass); writer.Write(HtmlTextWriter.SelfClosingTagEnd); writer.Write(i.ToString()); writer.WriteEndTag("a"); } writer.Write("\r\n"); } // write out last page link if (ShowFirstAndLastPageLinks && _endPage < TotalPages) { writer.WriteBeginTag("a"); string pageUrl = StringUtils.SetUrlEncodedKey(BaseUrl, QueryStringPageField, TotalPages.ToString()); writer.WriteAttribute("href", pageUrl); if (!string.IsNullOrEmpty(PageLinkCssClass)) writer.WriteAttribute("class", PageLinkCssClass + " " + PageLinkCssClass + "-last"); writer.Write(HtmlTextWriter.SelfClosingTagEnd); writer.Write(TotalPages.ToString()); writer.WriteEndTag("a"); } // Previous link if (ShowPreviousNextLinks && !string.IsNullOrEmpty(PreviousText) && ActivePage > 1) { writer.Write("&nbsp;"); writer.WriteBeginTag("a"); string pageUrl = StringUtils.SetUrlEncodedKey(BaseUrl, QueryStringPageField, (ActivePage - 1).ToString()); writer.WriteAttribute("href", pageUrl); if (!string.IsNullOrEmpty(PageLinkCssClass)) writer.WriteAttribute("class", PageLinkCssClass + " " + PageLinkCssClass + "-prev"); writer.Write(HtmlTextWriter.SelfClosingTagEnd); writer.Write(PreviousText); writer.WriteEndTag("a"); } // Next link if (ShowPreviousNextLinks && !string.IsNullOrEmpty(NextText) && ActivePage < TotalPages) { writer.Write("&nbsp;"); writer.WriteBeginTag("a"); string pageUrl = StringUtils.SetUrlEncodedKey(BaseUrl, QueryStringPageField, (ActivePage + 1).ToString()); writer.WriteAttribute("href", pageUrl); if (!string.IsNullOrEmpty(PageLinkCssClass)) writer.WriteAttribute("class", PageLinkCssClass + " " + PageLinkCssClass + "-next"); writer.Write(HtmlTextWriter.SelfClosingTagEnd); writer.Write(NextText); writer.WriteEndTag("a"); } writer.WriteEndTag("div"); if (RenderContainerDiv) { if (RenderContainerDivBreak) writer.Write("<br clear=\"all\" />\r\n"); writer.WriteEndTag("div"); } } As I said pretty much brute force rendering based on the control’s property settings of which there are quite a few: You can also see the pager in the designer above. unfortunately the VS designer (both 2010 and 2008) fails to render the float: left CSS styles properly and starts wrapping after margins are applied in the special buttons. Not a big deal since VS does at least respect the spacing (the floated elements overlay). Then again I’m not using the designer anyway :-}. Filtering Data What makes the Pager easy to use is the filter methods built into the control. While this functionality is clearly not the most politically correct design choice as it violates separation of concerns, it’s very useful for typical pager operation. While I actually have filter methods that do something similar in my business layer, having it exposed on the control makes the control a lot more useful for typical databinding scenarios. Of course these methods are optional – if you have a business layer that can provide filtered page queries for you can use that instead and assign the TotalItems property manually. There are three filter method types available for IQueryable, IEnumerable and for DataTable which tend to be the most common use cases in my apps old and new. The IQueryable version is pretty simple as it can simply rely on on .Skip() and .Take() with LINQ: /// <summary> /// <summary> /// Queries the database for the ActivePage applied manually /// or from the Request["page"] variable. This routine /// figures out and sets TotalPages, ActivePage and /// returns a filtered subset IQueryable that contains /// only the items from the ActivePage. /// </summary> /// <param name="query"></param> /// <param name="activePage"> /// The page you want to display. Sets the ActivePage property when passed. /// Pass 0 or smaller to use ActivePage setting. /// </param> /// <returns></returns> public IQueryable<T> FilterIQueryable<T>(IQueryable<T> query, int activePage) where T : class, new() { ActivePage = activePage < 1 ? ActivePage : activePage; if (ActivePage < 1) ActivePage = 1; TotalItems = query.Count(); if (TotalItems <= PageSize) { ActivePage = 1; TotalPages = 1; return query; } int skip = ActivePage - 1; if (skip > 0) query = query.Skip(skip * PageSize); _TotalPages = CalculateTotalPagesFromTotalItems(); return query.Take(PageSize); } The IEnumerable<T> version simply  converts the IEnumerable to an IQuerable and calls back into this method for filtering. The DataTable version requires a little more work to manually parse and filter records (I didn’t want to add the Linq DataSetExtensions assembly just for this): /// <summary> /// Filters a data table for an ActivePage. /// /// Note: Modifies the data set permanently by remove DataRows /// </summary> /// <param name="dt">Full result DataTable</param> /// <param name="activePage">Page to display. 0 to use ActivePage property </param> /// <returns></returns> public DataTable FilterDataTable(DataTable dt, int activePage) { ActivePage = activePage < 1 ? ActivePage : activePage; if (ActivePage < 1) ActivePage = 1; TotalItems = dt.Rows.Count; if (TotalItems <= PageSize) { ActivePage = 1; TotalPages = 1; return dt; } int skip = ActivePage - 1; if (skip > 0) { for (int i = 0; i < skip * PageSize; i++ ) dt.Rows.RemoveAt(0); } while(dt.Rows.Count > PageSize) dt.Rows.RemoveAt(PageSize); return dt; } Using the Pager Control The pager as it is is a first cut I built a couple of weeks ago and since then have been tweaking a little as part of an internal project I’m working on. I’ve replaced a bunch of pagers on various older pages with this pager without any issues and have what now feels like a more consistent user interface where paging looks and feels the same across different controls. As a bonus I’m only loading the data from the database that I need to display a single page. With the preset class tags applied too adding a pager is now as easy as dropping the control and adding the style sheet for styling to be consistent – no fuss, no muss. Schweet. Hopefully some of you may find this as useful as I have or at least as a baseline to build ontop of… Resources The Pager is part of the West Wind Web & Ajax Toolkit Pager.cs Source Code (some toolkit dependencies) Westwind.css base stylesheet with .pager and .gridpager styles Pager Example Page © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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  • Building applications with WPF, MVVM and Prism(aka CAG)

    - by skjagini
    In this article I am going to walk through an application using WPF and Prism (aka composite application guidance, CAG) which simulates engaging a taxi (cab).  The rules are simple, the app would have3 screens A login screen to authenticate the user An information screen. A screen to engage the cab and roam around and calculating the total fare Metered Rate of Fare The meter is required to be engaged when a cab is occupied by anyone $3.00 upon entry $0.35 for each additional unit The unit fare is: one-fifth of a mile, when the cab is traveling at 6 miles an hour or more; or 60 seconds when not in motion or traveling at less than 12 miles per hour. Night surcharge of $.50 after 8:00 PM & before 6:00 AM Peak hour Weekday Surcharge of $1.00 Monday - Friday after 4:00 PM & before 8:00 PM New York State Tax Surcharge of $.50 per ride. Example: Friday (2010-10-08) 5:30pm Start at Lexington Ave & E 57th St End at Irving Pl & E 15th St Start = $3.00 Travels 2 miles at less than 6 mph for 15 minutes = $3.50 Travels at more than 12 mph for 5 minutes = $1.75 Peak hour Weekday Surcharge = $1.00 (ride started at 5:30 pm) New York State Tax Surcharge = $0.50 Before we dive into the app, I would like to give brief description about the framework.  If you want to jump on to the source code, scroll all the way to the end of the post. MVVM MVVM pattern is in no way related to the usage of PRISM in your application and should be considered if you are using WPF irrespective of PRISM or not. Lets say you are not familiar with MVVM, your typical UI would involve adding some UI controls like text boxes, a button, double clicking on the button,  generating event handler, calling a method from business layer and updating the user interface, it works most of the time for developing small scale applications. The problem with this approach is that there is some amount of code specific to business logic wrapped in UI specific code which is hard to unit test it, mock it and MVVM helps to solve the exact problem. MVVM stands for Model(M) – View(V) – ViewModel(VM),  based on the interactions with in the three parties it should be called VVMM,  MVVM sounds more like MVC (Model-View-Controller) so the name. Why it should be called VVMM: View – View Model - Model WPF allows to create user interfaces using XAML and MVVM takes it to the next level by allowing complete separation of user interface and business logic. In WPF each view will have a property, DataContext when set to an instance of a class (which happens to be your view model) provides the data the view is interested in, i.e., view interacts with view model and at the same time view model interacts with view through DataContext. Sujith, if view and view model are interacting directly with each other how does MVVM is helping me separation of concerns? Well, the catch is DataContext is of type Object, since it is of type object view doesn’t know exact type of view model allowing views and views models to be loosely coupled. View models aggregate data from models (data access layer, services, etc) and make it available for views through properties, methods etc, i.e., View Models interact with Models. PRISM Prism is provided by Microsoft Patterns and Practices team and it can be downloaded from codeplex for source code,  samples and documentation on msdn.  The name composite implies, to compose user interface from different modules (views) without direct dependencies on each other, again allowing  loosely coupled development. Well Sujith, I can already do that with user controls, why shall I learn another framework?  That’s correct, you can decouple using user controls, but you still have to manage some amount of coupling, like how to do you communicate between the controls, how do you subscribe/unsubscribe, loading/unloading views dynamically. Prism is not a replacement for user controls, provides the following features which greatly help in designing the composite applications. Dependency Injection (DI)/ Inversion of Control (IoC) Modules Regions Event Aggregator  Commands Simply put, MVVM helps building a single view and Prism helps building an application using the views There are other open source alternatives to Prism, like MVVMLight, Cinch, take a look at them as well. Lets dig into the source code.  1. Solution The solution is made of the following projects Framework: Holds the common functionality in building applications using WPF and Prism TaxiClient: Start up project, boot strapping and app styling TaxiCommon: Helps with the business logic TaxiModules: Holds the meat of the application with views and view models TaxiTests: To test the application 2. DI / IoC Dependency Injection (DI) as the name implies refers to injecting dependencies and Inversion of Control (IoC) means the calling code has no direct control on the dependencies, opposite of normal way of programming where dependencies are passed by caller, i.e inversion; aside from some differences in terminology the concept is same in both the cases. The idea behind DI/IoC pattern is to reduce the amount of direct coupling between different components of the application, the higher the dependency the more tightly coupled the application resulting in code which is hard to modify, unit test and mock.  Initializing Dependency Injection through BootStrapper TaxiClient is the starting project of the solution and App (App.xaml)  is the starting class that gets called when you run the application. From the App’s OnStartup method we will invoke BootStrapper.   namespace TaxiClient { /// <summary> /// Interaction logic for App.xaml /// </summary> public partial class App : Application { protected override void OnStartup(StartupEventArgs e) { base.OnStartup(e);   (new BootStrapper()).Run(); } } } BootStrapper is your contact point for initializing the application including dependency injection, creating Shell and other frameworks. We are going to use Unity for DI and there are lot of open source DI frameworks like Spring.Net, StructureMap etc with different feature set  and you can choose a framework based on your preferences. Note that Prism comes with in built support for Unity, for example we are deriving from UnityBootStrapper in our case and for any other DI framework you have to extend the Prism appropriately   namespace TaxiClient { public class BootStrapper: UnityBootstrapper { protected override IModuleCatalog CreateModuleCatalog() { return new ConfigurationModuleCatalog(); } protected override DependencyObject CreateShell() { Framework.FrameworkBootStrapper.Run(Container, Application.Current.Dispatcher);   Shell shell = new Shell(); shell.ResizeMode = ResizeMode.NoResize; shell.Show();   return shell; } } } Lets take a look into  FrameworkBootStrapper to check out how to register with unity container. namespace Framework { public class FrameworkBootStrapper { public static void Run(IUnityContainer container, Dispatcher dispatcher) { UIDispatcher uiDispatcher = new UIDispatcher(dispatcher); container.RegisterInstance<IDispatcherService>(uiDispatcher);   container.RegisterType<IInjectSingleViewService, InjectSingleViewService>( new ContainerControlledLifetimeManager());   . . . } } } In the above code we are registering two components with unity container. You shall observe that we are following two different approaches, RegisterInstance and RegisterType.  With RegisterInstance we are registering an existing instance and the same instance will be returned for every request made for IDispatcherService   and with RegisterType we are requesting unity container to create an instance for us when required, i.e., when I request for an instance for IInjectSingleViewService, unity will create/return an instance of InjectSingleViewService class and with RegisterType we can configure the life time of the instance being created. With ContaienrControllerLifetimeManager, the unity container caches the instance and reuses for any subsequent requests, without recreating a new instance. Lets take a look into FareViewModel.cs and it’s constructor. The constructor takes one parameter IEventAggregator and if you try to find all references in your solution for IEventAggregator, you will not find a single location where an instance of EventAggregator is passed directly to the constructor. The compiler still finds an instance and works fine because Prism is already configured when used with Unity container to return an instance of EventAggregator when requested for IEventAggregator and in this particular case it is called constructor injection. public class FareViewModel:ObservableBase, IDataErrorInfo { ... private IEventAggregator _eventAggregator;   public FareViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator; InitializePropertyNames(); InitializeModel(); PropertyChanged += OnPropertyChanged; } ... 3. Shell Shells are very similar in operation to Master Pages in asp.net or MDI in Windows Forms. And shells contain regions which display the views, you can have as many regions as you wish in a given view. You can also nest regions. i.e, one region can load a view which in itself may contain other regions. We have to create a shell at the start of the application and are doing it by overriding CreateShell method from BootStrapper From the following Shell.xaml you shall notice that we have two content controls with Region names as ‘MenuRegion’ and ‘MainRegion’.  The idea here is that you can inject any user controls into the regions dynamically, i.e., a Menu User Control for MenuRegion and based on the user action you can load appropriate view into MainRegion.    <Window x:Class="TaxiClient.Shell" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Regions="clr-namespace:Microsoft.Practices.Prism.Regions;assembly=Microsoft.Practices.Prism" Title="Taxi" Height="370" Width="800"> <Grid Margin="2"> <ContentControl Regions:RegionManager.RegionName="MenuRegion" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" />   <ContentControl Grid.Row="1" Regions:RegionManager.RegionName="MainRegion" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" /> <!--<Border Grid.ColumnSpan="2" BorderThickness="2" CornerRadius="3" BorderBrush="LightBlue" />-->   </Grid> </Window> 4. Modules Prism provides the ability to build composite applications and modules play an important role in it. For example if you are building a Mortgage Loan Processor application with 3 components, i.e. customer’s credit history,  existing mortgages, new home/loan information; and consider that the customer’s credit history component involves gathering data about his/her address, background information, job details etc. The idea here using Prism modules is to separate the implementation of these 3 components into their own visual studio projects allowing to build components with no dependency on each other and independently. If we need to add another component to the application, the component can be developed by in house team or some other team in the organization by starting with a new Visual Studio project and adding to the solution at the run time with very little knowledge about the application. Prism modules are defined by implementing the IModule interface and each visual studio project to be considered as a module should implement the IModule interface.  From the BootStrapper.cs you shall observe that we are overriding the method by returning a ConfiguratingModuleCatalog which returns the modules that are registered for the application using the app.config file  and you can also add module using code. Lets take a look into configuration file.   <?xml version="1.0"?> <configuration> <configSections> <section name="modules" type="Microsoft.Practices.Prism.Modularity.ModulesConfigurationSection, Microsoft.Practices.Prism"/> </configSections> <modules> <module assemblyFile="TaxiModules.dll" moduleType="TaxiModules.ModuleInitializer, TaxiModules" moduleName="TaxiModules"/> </modules> </configuration> Here we are adding TaxiModules project to our solution and TaxiModules.ModuleInitializer implements IModule interface   5. Module Mapper With Prism modules you can dynamically add or remove modules from the regions, apart from that Prism also provides API to control adding/removing the views from a region within the same module. Taxi Information Screen: Engage the Taxi Screen: The sample application has two screens, ‘Taxi Information’ and ‘Engage the Taxi’ and they both reside in same module, TaxiModules. ‘Engage the Taxi’ is again made of two user controls, FareView on the left and TotalView on the right. We have created a Shell with two regions, MenuRegion and MainRegion with menu loaded into MenuRegion. We can create a wrapper user control called EngageTheTaxi made of FareView and TotalView and load either TaxiInfo or EngageTheTaxi into MainRegion based on the user action. Though it will work it tightly binds the user controls and for every combination of user controls, we need to create a dummy wrapper control to contain them. Instead we can apply the principles we learned so far from Shell/regions and introduce another template (LeftAndRightRegionView.xaml) made of two regions Region1 (left) and Region2 (right) and load  FareView and TotalView dynamically.  To help with loading of the views dynamically I have introduce an helper an interface, IInjectSingleViewService,  idea suggested by Mike Taulty, a must read blog for .Net developers. using System; using System.Collections.Generic; using System.ComponentModel;   namespace Framework.PresentationUtility.Navigation {   public interface IInjectSingleViewService : INotifyPropertyChanged { IEnumerable<CommandViewDefinition> Commands { get; } IEnumerable<ModuleViewDefinition> Modules { get; }   void RegisterViewForRegion(string commandName, string viewName, string regionName, Type viewType); void ClearViewFromRegion(string viewName, string regionName); void RegisterModule(string moduleName, IList<ModuleMapper> moduleMappers); } } The Interface declares three methods to work with views: RegisterViewForRegion: Registers a view with a particular region. You can register multiple views and their regions under one command.  When this particular command is invoked all the views registered under it will be loaded into their regions. ClearViewFromRegion: To unload a specific view from a region. RegisterModule: The idea is when a command is invoked you can load the UI with set of controls in their default position and based on the user interaction, you can load different contols in to different regions on the fly.  And it is supported ModuleViewDefinition and ModuleMappers as shown below. namespace Framework.PresentationUtility.Navigation { public class ModuleViewDefinition { public string ModuleName { get; set; } public IList<ModuleMapper> ModuleMappers; public ICommand Command { get; set; } }   public class ModuleMapper { public string ViewName { get; set; } public string RegionName { get; set; } public Type ViewType { get; set; } } } 6. Event Aggregator Prism event aggregator enables messaging between components as in Observable pattern, Notifier notifies the Observer which receives notification it is interested in. When it comes to Observable pattern, Observer has to unsubscribes for notifications when it no longer interested in notifications, which allows the Notifier to remove the Observer’s reference from it’s local cache. Though .Net has managed garbage collection it cannot remove inactive the instances referenced by an active instance resulting in memory leak, keeping the Observers in memory as long as Notifier stays in memory.  Developers have to be very careful to unsubscribe when necessary and it often gets overlooked, to overcome these problems Prism Event Aggregator uses weak references to cache the reference (Observer in this case)  and releases the reference (memory) once the instance goes out of scope. Using event aggregator is very simple, declare a generic type of CompositePresenationEvent by inheriting from it. using Microsoft.Practices.Prism.Events; using TaxiCommon.BAO;   namespace TaxiCommon.CompositeEvents { public class TaxiOnMoveEvent:CompositePresentationEvent<TaxiOnMove> { } }   TaxiOnMove.cs includes the properties which we want to exchange between the parties, FareView and TotalView. using System;   namespace TaxiCommon.BAO { public class TaxiOnMove { public TimeSpan MinutesAtTweleveMPH { get; set; } public double MilesAtSixMPH { get; set; } } }   Lets take a look into FareViewodel (Notifier) and how it raises the event.  Here we are raising the event by getting the event through GetEvent<..>() and publishing it with the payload private void OnAddMinutes(object obj) { TaxiOnMove payload = new TaxiOnMove(); if(MilesAtSixMPH != null) payload.MilesAtSixMPH = MilesAtSixMPH.Value; if(MinutesAtTweleveMPH != null) payload.MinutesAtTweleveMPH = new TimeSpan(0,0,MinutesAtTweleveMPH.Value,0);   _eventAggregator.GetEvent<TaxiOnMoveEvent>().Publish(payload); ResetMinutesAndMiles(); } And TotalViewModel(Observer) subscribes to notifications by getting the event through GetEvent<..>() namespace TaxiModules.ViewModels { public class TotalViewModel:ObservableBase { .... private IEventAggregator _eventAggregator;   public TotalViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator; ... }   private void SubscribeToEvents() { _eventAggregator.GetEvent<TaxiStartedEvent>() .Subscribe(OnTaxiStarted, ThreadOption.UIThread,false,(filter) => true); _eventAggregator.GetEvent<TaxiOnMoveEvent>() .Subscribe(OnTaxiMove, ThreadOption.UIThread, false, (filter) => true); _eventAggregator.GetEvent<TaxiResetEvent>() .Subscribe(OnTaxiReset, ThreadOption.UIThread, false, (filter) => true); }   ... private void OnTaxiMove(TaxiOnMove taxiOnMove) { OnMoveFare fare = new OnMoveFare(taxiOnMove); Fares.Add(fare); SetTotalFare(new []{fare}); }   .... 7. MVVM through example In this section we are going to look into MVVM implementation through example.  I have all the modules declared in a single project, TaxiModules, again it is not necessary to have them into one project. Once the user logs into the application, will be greeted with the ‘Engage the Taxi’ screen which is made of two user controls, FareView.xaml and TotalView.Xaml. As you can see from the solution explorer, each of them have their own code behind files and  ViewModel classes, FareViewMode.cs, TotalViewModel.cs Lets take a look in to the FareView and how it interacts with FareViewModel using MVVM implementation. FareView.xaml acts as a view and FareViewMode.cs is it’s view model. The FareView code behind class   namespace TaxiModules.Views { /// <summary> /// Interaction logic for FareView.xaml /// </summary> public partial class FareView : UserControl { public FareView(FareViewModel viewModel) { InitializeComponent(); this.Loaded += (s, e) => { this.DataContext = viewModel; }; } } } The FareView is bound to FareViewModel through the data context  and you shall observe that DataContext is of type Object, i.e. the FareView doesn’t really know the type of ViewModel (FareViewModel). This helps separation of View and ViewModel as View and ViewModel are independent of each other, you can bind FareView to FareViewModel2 as well and the application compiles just fine. Lets take a look into FareView xaml file  <UserControl x:Class="TaxiModules.Views.FareView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Toolkit="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit" xmlns:Commands="clr-namespace:Microsoft.Practices.Prism.Commands;assembly=Microsoft.Practices.Prism"> <Grid Margin="10" > ....   <Border Style="{DynamicResource innerBorder}" Grid.Row="0" Grid.Column="0" Grid.RowSpan="11" Grid.ColumnSpan="2" Panel.ZIndex="1"/>   <Label Grid.Row="0" Content="Engage the Taxi" Style="{DynamicResource innerHeader}"/> <Label Grid.Row="1" Content="Select the State"/> <ComboBox Grid.Row="1" Grid.Column="1" ItemsSource="{Binding States}" Height="auto"> <ComboBox.ItemTemplate> <DataTemplate> <TextBlock Text="{Binding Name}"/> </DataTemplate> </ComboBox.ItemTemplate> <ComboBox.SelectedItem> <Binding Path="SelectedState" Mode="TwoWay"/> </ComboBox.SelectedItem> </ComboBox> <Label Grid.Row="2" Content="Select the Date of Entry"/> <Toolkit:DatePicker Grid.Row="2" Grid.Column="1" SelectedDate="{Binding DateOfEntry, ValidatesOnDataErrors=true}" /> <Label Grid.Row="3" Content="Enter time 24hr format"/> <TextBox Grid.Row="3" Grid.Column="1" Text="{Binding TimeOfEntry, TargetNullValue=''}"/> <Button Grid.Row="4" Grid.Column="1" Content="Start the Meter" Commands:Click.Command="{Binding StartMeterCommand}" />   <Label Grid.Row="5" Content="Run the Taxi" Style="{DynamicResource innerHeader}"/> <Label Grid.Row="6" Content="Number of Miles &lt;@6mph"/> <TextBox Grid.Row="6" Grid.Column="1" Text="{Binding MilesAtSixMPH, TargetNullValue='', ValidatesOnDataErrors=true}"/> <Label Grid.Row="7" Content="Number of Minutes @12mph"/> <TextBox Grid.Row="7" Grid.Column="1" Text="{Binding MinutesAtTweleveMPH, TargetNullValue=''}"/> <Button Grid.Row="8" Grid.Column="1" Content="Add Minutes and Miles " Commands:Click.Command="{Binding AddMinutesCommand}"/> <Label Grid.Row="9" Content="Other Operations" Style="{DynamicResource innerHeader}"/> <Button Grid.Row="10" Grid.Column="1" Content="Reset the Meter" Commands:Click.Command="{Binding ResetCommand}"/>   </Grid> </UserControl> The highlighted code from the above code shows data binding, for example ComboBox which displays list of states has it’s ItemsSource bound to States property, with DataTemplate bound to Name and SelectedItem  to SelectedState. You might be wondering what are all these properties and how it is able to bind to them.  The answer lies in data context, i.e., when you bound a control, WPF looks for data context on the root object (Grid in this case) and if it can’t find data context it will look into root’s root, i.e. FareView UserControl and it is bound to FareViewModel.  Each of those properties have be declared on the ViewModel for the View to bind correctly. To put simply, View is bound to ViewModel through data context of type object and every control that is bound on the View actually binds to the public property on the ViewModel. Lets look into the ViewModel code (the following code is not an exact copy of FareViewMode.cs, pasted relevant code for this section)   namespace TaxiModules.ViewModels { public class FareViewModel:ObservableBase, IDataErrorInfo { public List<USState> States { get { return USStates.StateList; } }   public USState SelectedState { get { return _selectedState; } set { _selectedState = value; RaisePropertyChanged(_selectedStatePropertyName); } }   public DateTime? DateOfEntry { get { return _dateOfEntry; } set { _dateOfEntry = value; RaisePropertyChanged(_dateOfEntryPropertyName); } }   public TimeSpan? TimeOfEntry { get { return _timeOfEntry; } set { _timeOfEntry = value; RaisePropertyChanged(_timeOfEntryPropertyName); } }   public double? MilesAtSixMPH { get { return _milesAtSixMPH; } set { _milesAtSixMPH = value; RaisePropertyChanged(_distanceAtSixMPHPropertyName); } }   public int? MinutesAtTweleveMPH { get { return _minutesAtTweleveMPH; } set { _minutesAtTweleveMPH = value; RaisePropertyChanged(_minutesAtTweleveMPHPropertyName); } }   public ICommand StartMeterCommand { get { if(_startMeterCommand == null) { _startMeterCommand = new DelegateCommand<object>(OnStartMeter, CanStartMeter); } return _startMeterCommand; } }   public ICommand AddMinutesCommand { get { if(_addMinutesCommand == null) { _addMinutesCommand = new DelegateCommand<object>(OnAddMinutes, CanAddMinutes); } return _addMinutesCommand; } }   public ICommand ResetCommand { get { if(_resetCommand == null) { _resetCommand = new DelegateCommand<object>(OnResetCommand); } return _resetCommand; } }   } private void OnStartMeter(object obj) { _eventAggregator.GetEvent<TaxiStartedEvent>().Publish( new TaxiStarted() { EngagedOn = DateOfEntry.Value.Date + TimeOfEntry.Value, EngagedState = SelectedState.Value });   _isMeterStarted = true; OnPropertyChanged(this,null); } And views communicate user actions like button clicks, tree view item selections, etc using commands. When user clicks on ‘Start the Meter’ button it invokes the method StartMeterCommand, which calls the method OnStartMeter which publishes the event to TotalViewModel using event aggregator  and TaxiStartedEvent. namespace TaxiModules.ViewModels { public class TotalViewModel:ObservableBase { ... private IEventAggregator _eventAggregator;   public TotalViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator;   InitializePropertyNames(); InitializeModel(); SubscribeToEvents(); }   public decimal? TotalFare { get { return _totalFare; } set { _totalFare = value; RaisePropertyChanged(_totalFarePropertyName); } } .... private void SubscribeToEvents() { _eventAggregator.GetEvent<TaxiStartedEvent>().Subscribe(OnTaxiStarted, ThreadOption.UIThread,false,(filter) => true); _eventAggregator.GetEvent<TaxiOnMoveEvent>().Subscribe(OnTaxiMove, ThreadOption.UIThread, false, (filter) => true); _eventAggregator.GetEvent<TaxiResetEvent>().Subscribe(OnTaxiReset, ThreadOption.UIThread, false, (filter) => true); }   private void OnTaxiStarted(TaxiStarted taxiStarted) { Fares.Add(new EntryFare()); Fares.Add(new StateTaxFare(taxiStarted)); Fares.Add(new NightSurchargeFare(taxiStarted)); Fares.Add(new PeakHourWeekdayFare(taxiStarted));   SetTotalFare(Fares); }   private void SetTotalFare(IEnumerable<IFare> fares) { TotalFare = (_totalFare ?? 0) + TaxiFareHelper.GetTotalFare(fares); } ....   } }   TotalViewModel subscribes to events, TaxiStartedEvent and rest. When TaxiStartedEvent gets invoked it calls the OnTaxiStarted method which sets the total fare which includes entry fee, state tax, nightly surcharge, peak hour weekday fare.   Note that TotalViewModel derives from ObservableBase which implements the method RaisePropertyChanged which we are invoking in Set of TotalFare property, i.e, once we update the TotalFare property it raises an the event that  allows the TotalFare text box to fetch the new value through the data context. ViewModel is communicating with View through data context and it has no knowledge about View, helping in loose coupling of ViewModel and View.   I have attached the source code (.Net 4.0, Prism 4.0, VS 2010) , download and play with it and don’t forget to leave your comments.  

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  • Using the West Wind Web Toolkit to set up AJAX and REST Services

    - by Rick Strahl
    I frequently get questions about which option to use for creating AJAX and REST backends for ASP.NET applications. There are many solutions out there to do this actually, but when I have a choice - not surprisingly - I fall back to my own tools in the West Wind West Wind Web Toolkit. I've talked a bunch about the 'in-the-box' solutions in the past so for a change in this post I'll talk about the tools that I use in my own and customer applications to handle AJAX and REST based access to service resources using the West Wind West Wind Web Toolkit. Let me preface this by saying that I like things to be easy. Yes flexible is very important as well but not at the expense of over-complexity. The goal I've had with my tools is make it drop dead easy, with good performance while providing the core features that I'm after, which are: Easy AJAX/JSON Callbacks Ability to return any kind of non JSON content (string, stream, byte[], images) Ability to work with both XML and JSON interchangeably for input/output Access endpoints via POST data, RPC JSON calls, GET QueryString values or Routing interface Easy to use generic JavaScript client to make RPC calls (same syntax, just what you need) Ability to create clean URLS with Routing Ability to use standard ASP.NET HTTP Stack for HTTP semantics It's all about options! In this post I'll demonstrate most of these features (except XML) in a few simple and short samples which you can download. So let's take a look and see how you can build an AJAX callback solution with the West Wind Web Toolkit. Installing the Toolkit Assemblies The easiest and leanest way of using the Toolkit in your Web project is to grab it via NuGet: West Wind Web and AJAX Utilities (Westwind.Web) and drop it into the project by right clicking in your Project and choosing Manage NuGet Packages from anywhere in the Project.   When done you end up with your project looking like this: What just happened? Nuget added two assemblies - Westwind.Web and Westwind.Utilities and the client ww.jquery.js library. It also added a couple of references into web.config: The default namespaces so they can be accessed in pages/views and a ScriptCompressionModule that the toolkit optionally uses to compress script resources served from within the assembly (namely ww.jquery.js and optionally jquery.js). Creating a new Service The West Wind Web Toolkit supports several ways of creating and accessing AJAX services, but for this post I'll stick to the lower level approach that works from any plain HTML page or of course MVC, WebForms, WebPages. There's also a WebForms specific control that makes this even easier but I'll leave that for another post. So, to create a new standalone AJAX/REST service we can create a new HttpHandler in the new project either as a pure class based handler or as a generic .ASHX handler. Both work equally well, but generic handlers don't require any web.config configuration so I'll use that here. In the root of the project add a Generic Handler. I'm going to call this one StockService.ashx. Once the handler has been created, edit the code and remove all of the handler body code. Then change the base class to CallbackHandler and add methods that have a [CallbackMethod] attribute. Here's the modified base handler implementation now looks like with an added HelloWorld method: using System; using Westwind.Web; namespace WestWindWebAjax { /// <summary> /// Handler implements CallbackHandler to provide REST/AJAX services /// </summary> public class SampleService : CallbackHandler { [CallbackMethod] public string HelloWorld(string name) { return "Hello " + name + ". Time is: " + DateTime.Now.ToString(); } } } Notice that the class inherits from CallbackHandler and that the HelloWorld service method is marked up with [CallbackMethod]. We're done here. Services Urlbased Syntax Once you compile, the 'service' is live can respond to requests. All CallbackHandlers support input in GET and POST formats, and can return results as JSON or XML. To check our fancy HelloWorld method we can now access the service like this: http://localhost/WestWindWebAjax/StockService.ashx?Method=HelloWorld&name=Rick which produces a default JSON response - in this case a string (wrapped in quotes as it's JSON): (note by default JSON will be downloaded by most browsers not displayed - various options are available to view JSON right in the browser) If I want to return the same data as XML I can tack on a &format=xml at the end of the querystring which produces: <string>Hello Rick. Time is: 11/1/2011 12:11:13 PM</string> Cleaner URLs with Routing Syntax If you want cleaner URLs for each operation you can also configure custom routes on a per URL basis similar to the way that WCF REST does. To do this you need to add a new RouteHandler to your application's startup code in global.asax.cs one for each CallbackHandler based service you create: protected void Application_Start(object sender, EventArgs e) { CallbackHandlerRouteHandler.RegisterRoutes<StockService>(RouteTable.Routes); } With this code in place you can now add RouteUrl properties to any of your service methods. For the HelloWorld method that doesn't make a ton of sense but here is what a routed clean URL might look like in definition: [CallbackMethod(RouteUrl="stocks/HelloWorld/{name}")] public string HelloWorld(string name) { return "Hello " + name + ". Time is: " + DateTime.Now.ToString(); } The same URL I previously used now becomes a bit shorter and more readable with: http://localhost/WestWindWebAjax/HelloWorld/Rick It's an easy way to create cleaner URLs and still get the same functionality. Calling the Service with $.getJSON() Since the result produced is JSON you can now easily consume this data using jQuery's getJSON method. First we need a couple of scripts - jquery.js and ww.jquery.js in the page: <!DOCTYPE html> <html> <head> <link href="Css/Westwind.css" rel="stylesheet" type="text/css" /> <script src="scripts/jquery.min.js" type="text/javascript"></script> <script src="scripts/ww.jquery.min.js" type="text/javascript"></script> </head> <body> Next let's add a small HelloWorld example form (what else) that has a single textbox to type a name, a button and a div tag to receive the result: <fieldset> <legend>Hello World</legend> Please enter a name: <input type="text" name="txtHello" id="txtHello" value="" /> <input type="button" id="btnSayHello" value="Say Hello (POST)" /> <input type="button" id="btnSayHelloGet" value="Say Hello (GET)" /> <div id="divHelloMessage" class="errordisplay" style="display:none;width: 450px;" > </div> </fieldset> Then to call the HelloWorld method a little jQuery is used to hook the document startup and the button click followed by the $.getJSON call to retrieve the data from the server. <script type="text/javascript"> $(document).ready(function () { $("#btnSayHelloGet").click(function () { $.getJSON("SampleService.ashx", { Method: "HelloWorld", name: $("#txtHello").val() }, function (result) { $("#divHelloMessage") .text(result) .fadeIn(1000); }); });</script> .getJSON() expects a full URL to the endpoint of our service, which is the ASHX file. We can either provide a full URL (SampleService.ashx?Method=HelloWorld&name=Rick) or we can just provide the base URL and an object that encodes the query string parameters for us using an object map that has a property that matches each parameter for the server method. We can also use the clean URL routing syntax, but using the object parameter encoding actually is safer as the parameters will get properly encoded by jQuery. The result returned is whatever the result on the server method is - in this case a string. The string is applied to the divHelloMessage element and we're done. Obviously this is a trivial example, but it demonstrates the basics of getting a JSON response back to the browser. AJAX Post Syntax - using ajaxCallMethod() The previous example allows you basic control over the data that you send to the server via querystring parameters. This works OK for simple values like short strings, numbers and boolean values, but doesn't really work if you need to pass something more complex like an object or an array back up to the server. To handle traditional RPC type messaging where the idea is to map server side functions and results to a client side invokation, POST operations can be used. The easiest way to use this functionality is to use ww.jquery.js and the ajaxCallMethod() function. ww.jquery wraps jQuery's AJAX functions and knows implicitly how to call a CallbackServer method with parameters and parse the result. Let's look at another simple example that posts a simple value but returns something more interesting. Let's start with the service method: [CallbackMethod(RouteUrl="stocks/{symbol}")] public StockQuote GetStockQuote(string symbol) { Response.Cache.SetExpires(DateTime.UtcNow.Add(new TimeSpan(0, 2, 0))); StockServer server = new StockServer(); var quote = server.GetStockQuote(symbol); if (quote == null) throw new ApplicationException("Invalid Symbol passed."); return quote; } This sample utilizes a small StockServer helper class (included in the sample) that downloads a stock quote from Yahoo's financial site via plain HTTP GET requests and formats it into a StockQuote object. Lets create a small HTML block that lets us query for the quote and display it: <fieldset> <legend>Single Stock Quote</legend> Please enter a stock symbol: <input type="text" name="txtSymbol" id="txtSymbol" value="msft" /> <input type="button" id="btnStockQuote" value="Get Quote" /> <div id="divStockDisplay" class="errordisplay" style="display:none; width: 450px;"> <div class="label-left">Company:</div> <div id="stockCompany"></div> <div class="label-left">Last Price:</div> <div id="stockLastPrice"></div> <div class="label-left">Quote Time:</div> <div id="stockQuoteTime"></div> </div> </fieldset> The final result looks something like this:   Let's hook up the button handler to fire the request and fill in the data as shown: $("#btnStockQuote").click(function () { ajaxCallMethod("SampleService.ashx", "GetStockQuote", [$("#txtSymbol").val()], function (quote) { $("#divStockDisplay").show().fadeIn(1000); $("#stockCompany").text(quote.Company + " (" + quote.Symbol + ")"); $("#stockLastPrice").text(quote.LastPrice); $("#stockQuoteTime").text(quote.LastQuoteTime.formatDate("MMM dd, HH:mm EST")); }, onPageError); }); So we point at SampleService.ashx and the GetStockQuote method, passing a single parameter of the input symbol value. Then there are two handlers for success and failure callbacks.  The success handler is the interesting part - it receives the stock quote as a result and assigns its values to various 'holes' in the stock display elements. The data that comes back over the wire is JSON and it looks like this: { "Symbol":"MSFT", "Company":"Microsoft Corpora", "OpenPrice":26.11, "LastPrice":26.01, "NetChange":0.02, "LastQuoteTime":"2011-11-03T02:00:00Z", "LastQuoteTimeString":"Nov. 11, 2011 4:20pm" } which is an object representation of the data. JavaScript can evaluate this JSON string back into an object easily and that's the reslut that gets passed to the success function. The quote data is then applied to existing page content by manually selecting items and applying them. There are other ways to do this more elegantly like using templates, but here we're only interested in seeing how the data is returned. The data in the object is typed - LastPrice is a number and QuoteTime is a date. Note about the date value: JavaScript doesn't have a date literal although the JSON embedded ISO string format used above  ("2011-11-03T02:00:00Z") is becoming fairly standard for JSON serializers. However, JSON parsers don't deserialize dates by default and return them by string. This is why the StockQuote actually returns a string value of LastQuoteTimeString for the same date. ajaxMethodCallback always converts dates properly into 'real' dates and the example above uses the real date value along with a .formatDate() data extension (also in ww.jquery.js) to display the raw date properly. Errors and Exceptions So what happens if your code fails? For example if I pass an invalid stock symbol to the GetStockQuote() method you notice that the code does this: if (quote == null) throw new ApplicationException("Invalid Symbol passed."); CallbackHandler automatically pushes the exception message back to the client so it's easy to pick up the error message. Regardless of what kind of error occurs: Server side, client side, protocol errors - any error will fire the failure handler with an error object parameter. The error is returned to the client via a JSON response in the error callback. In the previous examples I called onPageError which is a generic routine in ww.jquery that displays a status message on the bottom of the screen. But of course you can also take over the error handling yourself: $("#btnStockQuote").click(function () { ajaxCallMethod("SampleService.ashx", "GetStockQuote", [$("#txtSymbol").val()], function (quote) { $("#divStockDisplay").fadeIn(1000); $("#stockCompany").text(quote.Company + " (" + quote.Symbol + ")"); $("#stockLastPrice").text(quote.LastPrice); $("#stockQuoteTime").text(quote.LastQuoteTime.formatDate("MMM dd, hh:mmt")); }, function (error, xhr) { $("#divErrorDisplay").text(error.message).fadeIn(1000); }); }); The error object has a isCallbackError, message and  stackTrace properties, the latter of which is only populated when running in Debug mode, and this object is returned for all errors: Client side, transport and server side errors. Regardless of which type of error you get the same object passed (as well as the XHR instance optionally) which makes for a consistent error retrieval mechanism. Specifying HttpVerbs You can also specify HTTP Verbs that are allowed using the AllowedHttpVerbs option on the CallbackMethod attribute: [CallbackMethod(AllowedHttpVerbs=HttpVerbs.GET | HttpVerbs.POST)] public string HelloWorld(string name) { … } If you're building REST style API's this might be useful to force certain request semantics onto the client calling. For the above if call with a non-allowed HttpVerb the request returns a 405 error response along with a JSON (or XML) error object result. The default behavior is to allow all verbs access (HttpVerbs.All). Passing in object Parameters Up to now the parameters I passed were very simple. But what if you need to send something more complex like an object or an array? Let's look at another example now that passes an object from the client to the server. Keeping with the Stock theme here lets add a method called BuyOrder that lets us buy some shares for a stock. Consider the following service method that receives an StockBuyOrder object as a parameter: [CallbackMethod] public string BuyStock(StockBuyOrder buyOrder) { var server = new StockServer(); var quote = server.GetStockQuote(buyOrder.Symbol); if (quote == null) throw new ApplicationException("Invalid or missing stock symbol."); return string.Format("You're buying {0} shares of {1} ({2}) stock at {3} for a total of {4} on {5}.", buyOrder.Quantity, quote.Company, quote.Symbol, quote.LastPrice.ToString("c"), (quote.LastPrice * buyOrder.Quantity).ToString("c"), buyOrder.BuyOn.ToString("MMM d")); } public class StockBuyOrder { public string Symbol { get; set; } public int Quantity { get; set; } public DateTime BuyOn { get; set; } public StockBuyOrder() { BuyOn = DateTime.Now; } } This is a contrived do-nothing example that simply echoes back what was passed in, but it demonstrates how you can pass complex data to a callback method. On the client side we now have a very simple form that captures the three values on a form: <fieldset> <legend>Post a Stock Buy Order</legend> Enter a symbol: <input type="text" name="txtBuySymbol" id="txtBuySymbol" value="GLD" />&nbsp;&nbsp; Qty: <input type="text" name="txtBuyQty" id="txtBuyQty" value="10" style="width: 50px" />&nbsp;&nbsp; Buy on: <input type="text" name="txtBuyOn" id="txtBuyOn" value="<%= DateTime.Now.ToString("d") %>" style="width: 70px;" /> <input type="button" id="btnBuyStock" value="Buy Stock" /> <div id="divStockBuyMessage" class="errordisplay" style="display:none"></div> </fieldset> The completed form and demo then looks something like this:   The client side code that picks up the input values and assigns them to object properties and sends the AJAX request looks like this: $("#btnBuyStock").click(function () { // create an object map that matches StockBuyOrder signature var buyOrder = { Symbol: $("#txtBuySymbol").val(), Quantity: $("#txtBuyQty").val() * 1, // number Entered: new Date() } ajaxCallMethod("SampleService.ashx", "BuyStock", [buyOrder], function (result) { $("#divStockBuyMessage").text(result).fadeIn(1000); }, onPageError); }); The code creates an object and attaches the properties that match the server side object passed to the BuyStock method. Each property that you want to update needs to be included and the type must match (ie. string, number, date in this case). Any missing properties will not be set but also not cause any errors. Pass POST data instead of Objects In the last example I collected a bunch of values from form variables and stuffed them into object variables in JavaScript code. While that works, often times this isn't really helping - I end up converting my types on the client and then doing another conversion on the server. If lots of input controls are on a page and you just want to pick up the values on the server via plain POST variables - that can be done too - and it makes sense especially if you're creating and filling the client side object only to push data to the server. Let's add another method to the server that once again lets us buy a stock. But this time let's not accept a parameter but rather send POST data to the server. Here's the server method receiving POST data: [CallbackMethod] public string BuyStockPost() { StockBuyOrder buyOrder = new StockBuyOrder(); buyOrder.Symbol = Request.Form["txtBuySymbol"]; ; int qty; int.TryParse(Request.Form["txtBuyQuantity"], out qty); buyOrder.Quantity = qty; DateTime time; DateTime.TryParse(Request.Form["txtBuyBuyOn"], out time); buyOrder.BuyOn = time; // Or easier way yet //FormVariableBinder.Unbind(buyOrder,null,"txtBuy"); var server = new StockServer(); var quote = server.GetStockQuote(buyOrder.Symbol); if (quote == null) throw new ApplicationException("Invalid or missing stock symbol."); return string.Format("You're buying {0} shares of {1} ({2}) stock at {3} for a total of {4} on {5}.", buyOrder.Quantity, quote.Company, quote.Symbol, quote.LastPrice.ToString("c"), (quote.LastPrice * buyOrder.Quantity).ToString("c"), buyOrder.BuyOn.ToString("MMM d")); } Clearly we've made this server method take more code than it did with the object parameter. We've basically moved the parameter assignment logic from the client to the server. As a result the client code to call this method is now a bit shorter since there's no client side shuffling of values from the controls to an object. $("#btnBuyStockPost").click(function () { ajaxCallMethod("SampleService.ashx", "BuyStockPost", [], // Note: No parameters - function (result) { $("#divStockBuyMessage").text(result).fadeIn(1000); }, onPageError, // Force all page Form Variables to be posted { postbackMode: "Post" }); }); The client simply calls the BuyStockQuote method and pushes all the form variables from the page up to the server which parses them instead. The feature that makes this work is one of the options you can pass to the ajaxCallMethod() function: { postbackMode: "Post" }); which directs the function to include form variable POST data when making the service call. Other options include PostNoViewState (for WebForms to strip out WebForms crap vars), PostParametersOnly (default), None. If you pass parameters those are always posted to the server except when None is set. The above code can be simplified a bit by using the FormVariableBinder helper, which can unbind form variables directly into an object: FormVariableBinder.Unbind(buyOrder,null,"txtBuy"); which replaces the manual Request.Form[] reading code. It receives the object to unbind into, a string of properties to skip, and an optional prefix which is stripped off form variables to match property names. The component is similar to the MVC model binder but it's independent of MVC. Returning non-JSON Data CallbackHandler also supports returning non-JSON/XML data via special return types. You can return raw non-JSON encoded strings like this: [CallbackMethod(ReturnAsRawString=true,ContentType="text/plain")] public string HelloWorldNoJSON(string name) { return "Hello " + name + ". Time is: " + DateTime.Now.ToString(); } Calling this method results in just a plain string - no JSON encoding with quotes around the result. This can be useful if your server handling code needs to return a string or HTML result that doesn't fit well for a page or other UI component. Any string output can be returned. You can also return binary data. Stream, byte[] and Bitmap/Image results are automatically streamed back to the client. Notice that you should set the ContentType of the request either on the CallbackMethod attribute or using Response.ContentType. This ensures the Web Server knows how to display your binary response. Using a stream response makes it possible to return any of data. Streamed data can be pretty handy to return bitmap data from a method. The following is a method that returns a stock history graph for a particular stock over a provided number of years: [CallbackMethod(ContentType="image/png",RouteUrl="stocks/history/graph/{symbol}/{years}")] public Stream GetStockHistoryGraph(string symbol, int years = 2,int width = 500, int height=350) { if (width == 0) width = 500; if (height == 0) height = 350; StockServer server = new StockServer(); return server.GetStockHistoryGraph(symbol,"Stock History for " + symbol,width,height,years); } I can now hook this up into the JavaScript code when I get a stock quote. At the end of the process I can assign the URL to the service that returns the image into the src property and so force the image to display. Here's the changed code: $("#btnStockQuote").click(function () { var symbol = $("#txtSymbol").val(); ajaxCallMethod("SampleService.ashx", "GetStockQuote", [symbol], function (quote) { $("#divStockDisplay").fadeIn(1000); $("#stockCompany").text(quote.Company + " (" + quote.Symbol + ")"); $("#stockLastPrice").text(quote.LastPrice); $("#stockQuoteTime").text(quote.LastQuoteTime.formatDate("MMM dd, hh:mmt")); // display a stock chart $("#imgStockHistory").attr("src", "stocks/history/graph/" + symbol + "/2"); },onPageError); }); The resulting output then looks like this: The charting code uses the new ASP.NET 4.0 Chart components via code to display a bar chart of the 2 year stock data as part of the StockServer class which you can find in the sample download. The ability to return arbitrary data from a service is useful as you can see - in this case the chart is clearly associated with the service and it's nice that the graph generation can happen off a handler rather than through a page. Images are common resources, but output can also be PDF reports, zip files for downloads etc. which is becoming increasingly more common to be returned from REST endpoints and other applications. Why reinvent? Obviously the examples I've shown here are pretty basic in terms of functionality. But I hope they demonstrate the core features of AJAX callbacks that you need to work through in most applications which is simple: return data, send back data and potentially retrieve data in various formats. While there are other solutions when it comes down to making AJAX callbacks and servicing REST like requests, I like the flexibility my home grown solution provides. Simply put it's still the easiest solution that I've found that addresses my common use cases: AJAX JSON RPC style callbacks Url based access XML and JSON Output from single method endpoint XML and JSON POST support, querystring input, routing parameter mapping UrlEncoded POST data support on callbacks Ability to return stream/raw string data Essentially ability to return ANYTHING from Service and pass anything All these features are available in various solutions but not together in one place. I've been using this code base for over 4 years now in a number of projects both for myself and commercial work and it's served me extremely well. Besides the AJAX functionality CallbackHandler provides, it's also an easy way to create any kind of output endpoint I need to create. Need to create a few simple routines that spit back some data, but don't want to create a Page or View or full blown handler for it? Create a CallbackHandler and add a method or multiple methods and you have your generic endpoints.  It's a quick and easy way to add small code pieces that are pretty efficient as they're running through a pretty small handler implementation. I can have this up and running in a couple of minutes literally without any setup and returning just about any kind of data. Resources Download the Sample NuGet: Westwind Web and AJAX Utilities (Westwind.Web) ajaxCallMethod() Documentation Using the AjaxMethodCallback WebForms Control West Wind Web Toolkit Home Page West Wind Web Toolkit Source Code © Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  jQuery  AJAX   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Custom ASP.NET Routing to an HttpHandler

    - by Rick Strahl
    As of version 4.0 ASP.NET natively supports routing via the now built-in System.Web.Routing namespace. Routing features are automatically integrated into the HtttpRuntime via a few custom interfaces. New Web Forms Routing Support In ASP.NET 4.0 there are a host of improvements including routing support baked into Web Forms via a RouteData property available on the Page class and RouteCollection.MapPageRoute() route handler that makes it easy to route to Web forms. To map ASP.NET Page routes is as simple as setting up the routes with MapPageRoute:protected void Application_Start(object sender, EventArgs e) { RegisterRoutes(RouteTable.Routes); } void RegisterRoutes(RouteCollection routes) { routes.MapPageRoute("StockQuote", "StockQuote/{symbol}", "StockQuote.aspx"); routes.MapPageRoute("StockQuotes", "StockQuotes/{symbolList}", "StockQuotes.aspx"); } and then accessing the route data in the page you can then use the new Page class RouteData property to retrieve the dynamic route data information:public partial class StockQuote1 : System.Web.UI.Page { protected StockQuote Quote = null; protected void Page_Load(object sender, EventArgs e) { string symbol = RouteData.Values["symbol"] as string; StockServer server = new StockServer(); Quote = server.GetStockQuote(symbol); // display stock data in Page View } } Simple, quick and doesn’t require much explanation. If you’re using WebForms most of your routing needs should be served just fine by this simple mechanism. Kudos to the ASP.NET team for putting this in the box and making it easy! How Routing Works To handle Routing in ASP.NET involves these steps: Registering Routes Creating a custom RouteHandler to retrieve an HttpHandler Attaching RouteData to your HttpHandler Picking up Route Information in your Request code Registering routes makes ASP.NET aware of the Routes you want to handle via the static RouteTable.Routes collection. You basically add routes to this collection to let ASP.NET know which URL patterns it should watch for. You typically hook up routes off a RegisterRoutes method that fires in Application_Start as I did in the example above to ensure routes are added only once when the application first starts up. When you create a route, you pass in a RouteHandler instance which ASP.NET caches and reuses as routes are matched. Once registered ASP.NET monitors the routes and if a match is found just prior to the HttpHandler instantiation, ASP.NET uses the RouteHandler registered for the route and calls GetHandler() on it to retrieve an HttpHandler instance. The RouteHandler.GetHandler() method is responsible for creating an instance of an HttpHandler that is to handle the request and – if necessary – to assign any additional custom data to the handler. At minimum you probably want to pass the RouteData to the handler so the handler can identify the request based on the route data available. To do this you typically add  a RouteData property to your handler and then assign the property from the RouteHandlers request context. This is essentially how Page.RouteData comes into being and this approach should work well for any custom handler implementation that requires RouteData. It’s a shame that ASP.NET doesn’t have a top level intrinsic object that’s accessible off the HttpContext object to provide route data more generically, but since RouteData is directly tied to HttpHandlers and not all handlers support it it might cause some confusion of when it’s actually available. Bottom line is that if you want to hold on to RouteData you have to assign it to a custom property of the handler or else pass it to the handler via Context.Items[] object that can be retrieved on an as needed basis. It’s important to understand that routing is hooked up via RouteHandlers that are responsible for loading HttpHandler instances. RouteHandlers are invoked for every request that matches a route and through this RouteHandler instance the Handler gains access to the current RouteData. Because of this logic it’s important to understand that Routing is really tied to HttpHandlers and not available prior to handler instantiation, which is pretty late in the HttpRuntime’s request pipeline. IOW, Routing works with Handlers but not with earlier in the pipeline within Modules. Specifically ASP.NET calls RouteHandler.GetHandler() from the PostResolveRequestCache HttpRuntime pipeline event. Here’s the call stack at the beginning of the GetHandler() call: which fires just before handler resolution. Non-Page Routing – You need to build custom RouteHandlers If you need to route to a custom Http Handler or other non-Page (and non-MVC) endpoint in the HttpRuntime, there is no generic mapping support available. You need to create a custom RouteHandler that can manage creating an instance of an HttpHandler that is fired in response to a routed request. Depending on what you are doing this process can be simple or fairly involved as your code is responsible based on the route data provided which handler to instantiate, and more importantly how to pass the route data on to the Handler. Luckily creating a RouteHandler is easy by implementing the IRouteHandler interface which has only a single GetHttpHandler(RequestContext context) method. In this method you can pick up the requestContext.RouteData, instantiate the HttpHandler of choice, and assign the RouteData to it. Then pass back the handler and you’re done.Here’s a simple example of GetHttpHandler() method that dynamically creates a handler based on a passed in Handler type./// <summary> /// Retrieves an Http Handler based on the type specified in the constructor /// </summary> /// <param name="requestContext"></param> /// <returns></returns> IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; // If we're dealing with a Callback Handler // pass the RouteData for this route to the Handler if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; } Note that this code checks for a specific type of handler and if it matches assigns the RouteData to this handler. This is optional but quite a common scenario if you want to work with RouteData. If the handler you need to instantiate isn’t under your control but you still need to pass RouteData to Handler code, an alternative is to pass the RouteData via the HttpContext.Items collection:IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; requestContext.HttpContext.Items["RouteData"] = requestContext.RouteData; return handler; } The code in the handler implementation can then pick up the RouteData from the context collection as needed:RouteData routeData = HttpContext.Current.Items["RouteData"] as RouteData This isn’t as clean as having an explicit RouteData property, but it does have the advantage that the route data is visible anywhere in the Handler’s code chain. It’s definitely preferable to create a custom property on your handler, but the Context work-around works in a pinch when you don’t’ own the handler code and have dynamic code executing as part of the handler execution. An Example of a Custom RouteHandler: Attribute Based Route Implementation In this post I’m going to discuss a custom routine implementation I built for my CallbackHandler class in the West Wind Web & Ajax Toolkit. CallbackHandler can be very easily used for creating AJAX, REST and POX requests following RPC style method mapping. You can pass parameters via URL query string, POST data or raw data structures, and you can retrieve results as JSON, XML or raw string/binary data. It’s a quick and easy way to build service interfaces with no fuss. As a quick review here’s how CallbackHandler works: You create an Http Handler that derives from CallbackHandler You implement methods that have a [CallbackMethod] Attribute and that’s it. Here’s an example of an CallbackHandler implementation in an ashx.cs based handler:// RestService.ashx.cs public class RestService : CallbackHandler { [CallbackMethod] public StockQuote GetStockQuote(string symbol) { StockServer server = new StockServer(); return server.GetStockQuote(symbol); } [CallbackMethod] public StockQuote[] GetStockQuotes(string symbolList) { StockServer server = new StockServer(); string[] symbols = symbolList.Split(new char[2] { ',',';' },StringSplitOptions.RemoveEmptyEntries); return server.GetStockQuotes(symbols); } } CallbackHandler makes it super easy to create a method on the server, pass data to it via POST, QueryString or raw JSON/XML data, and then retrieve the results easily back in various formats. This works wonderful and I’ve used these tools in many projects for myself and with clients. But one thing missing has been the ability to create clean URLs. Typical URLs looked like this: http://www.west-wind.com/WestwindWebToolkit/samples/Rest/StockService.ashx?Method=GetStockQuote&symbol=msfthttp://www.west-wind.com/WestwindWebToolkit/samples/Rest/StockService.ashx?Method=GetStockQuotes&symbolList=msft,intc,gld,slw,mwe&format=xml which works and is clear enough, but also clearly very ugly. It would be much nicer if URLs could look like this: http://www.west-wind.com//WestwindWebtoolkit/Samples/StockQuote/msfthttp://www.west-wind.com/WestwindWebtoolkit/Samples/StockQuotes/msft,intc,gld,slw?format=xml (the Virtual Root in this sample is WestWindWebToolkit/Samples and StockQuote/{symbol} is the route)(If you use FireFox try using the JSONView plug-in make it easier to view JSON content) So, taking a clue from the WCF REST tools that use RouteUrls I set out to create a way to specify RouteUrls for each of the endpoints. The change made basically allows changing the above to: [CallbackMethod(RouteUrl="RestService/StockQuote/{symbol}")] public StockQuote GetStockQuote(string symbol) { StockServer server = new StockServer(); return server.GetStockQuote(symbol); } [CallbackMethod(RouteUrl = "RestService/StockQuotes/{symbolList}")] public StockQuote[] GetStockQuotes(string symbolList) { StockServer server = new StockServer(); string[] symbols = symbolList.Split(new char[2] { ',',';' },StringSplitOptions.RemoveEmptyEntries); return server.GetStockQuotes(symbols); } where a RouteUrl is specified as part of the Callback attribute. And with the changes made with RouteUrls I can now get URLs like the second set shown earlier. So how does that work? Let’s find out… How to Create Custom Routes As mentioned earlier Routing is made up of several steps: Creating a custom RouteHandler to create HttpHandler instances Mapping the actual Routes to the RouteHandler Retrieving the RouteData and actually doing something useful with it in the HttpHandler In the CallbackHandler routing example above this works out to something like this: Create a custom RouteHandler that includes a property to track the method to call Set up the routes using Reflection against the class Looking for any RouteUrls in the CallbackMethod attribute Add a RouteData property to the CallbackHandler so we can access the RouteData in the code of the handler Creating a Custom Route Handler To make the above work I created a custom RouteHandler class that includes the actual IRouteHandler implementation as well as a generic and static method to automatically register all routes marked with the [CallbackMethod(RouteUrl="…")] attribute. Here’s the code:/// <summary> /// Route handler that can create instances of CallbackHandler derived /// callback classes. The route handler tracks the method name and /// creates an instance of the service in a predictable manner /// </summary> /// <typeparam name="TCallbackHandler">CallbackHandler type</typeparam> public class CallbackHandlerRouteHandler : IRouteHandler { /// <summary> /// Method name that is to be called on this route. /// Set by the automatically generated RegisterRoutes /// invokation. /// </summary> public string MethodName { get; set; } /// <summary> /// The type of the handler we're going to instantiate. /// Needed so we can semi-generically instantiate the /// handler and call the method on it. /// </summary> public Type CallbackHandlerType { get; set; } /// <summary> /// Constructor to pass in the two required components we /// need to create an instance of our handler. /// </summary> /// <param name="methodName"></param> /// <param name="callbackHandlerType"></param> public CallbackHandlerRouteHandler(string methodName, Type callbackHandlerType) { MethodName = methodName; CallbackHandlerType = callbackHandlerType; } /// <summary> /// Retrieves an Http Handler based on the type specified in the constructor /// </summary> /// <param name="requestContext"></param> /// <returns></returns> IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; // If we're dealing with a Callback Handler // pass the RouteData for this route to the Handler if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; } /// <summary> /// Generic method to register all routes from a CallbackHandler /// that have RouteUrls defined on the [CallbackMethod] attribute /// </summary> /// <typeparam name="TCallbackHandler">CallbackHandler Type</typeparam> /// <param name="routes"></param> public static void RegisterRoutes<TCallbackHandler>(RouteCollection routes) { // find all methods var methods = typeof(TCallbackHandler).GetMethods(BindingFlags.Instance | BindingFlags.Public); foreach (var method in methods) { var attrs = method.GetCustomAttributes(typeof(CallbackMethodAttribute), false); if (attrs.Length < 1) continue; CallbackMethodAttribute attr = attrs[0] as CallbackMethodAttribute; if (string.IsNullOrEmpty(attr.RouteUrl)) continue; // Add the route routes.Add(method.Name, new Route(attr.RouteUrl, new CallbackHandlerRouteHandler(method.Name, typeof(TCallbackHandler)))); } } } The RouteHandler implements IRouteHandler, and its responsibility via the GetHandler method is to create an HttpHandler based on the route data. When ASP.NET calls GetHandler it passes a requestContext parameter which includes a requestContext.RouteData property. This parameter holds the current request’s route data as well as an instance of the current RouteHandler. If you look at GetHttpHandler() you can see that the code creates an instance of the handler we are interested in and then sets the RouteData property on the handler. This is how you can pass the current request’s RouteData to the handler. The RouteData object also has a  RouteData.RouteHandler property that is also available to the Handler later, which is useful in order to get additional information about the current route. In our case here the RouteHandler includes a MethodName property that identifies the method to execute in the handler since that value no longer comes from the URL so we need to figure out the method name some other way. The method name is mapped explicitly when the RouteHandler is created and here the static method that auto-registers all CallbackMethods with RouteUrls sets the method name when it creates the routes while reflecting over the methods (more on this in a minute). The important point here is that you can attach additional properties to the RouteHandler and you can then later access the RouteHandler and its properties later in the Handler to pick up these custom values. This is a crucial feature in that the RouteHandler serves in passing additional context to the handler so it knows what actions to perform. The automatic route registration is handled by the static RegisterRoutes<TCallbackHandler> method. This method is generic and totally reusable for any CallbackHandler type handler. To register a CallbackHandler and any RouteUrls it has defined you simple use code like this in Application_Start (or other application startup code):protected void Application_Start(object sender, EventArgs e) { // Register Routes for RestService CallbackHandlerRouteHandler.RegisterRoutes<RestService>(RouteTable.Routes); } If you have multiple CallbackHandler style services you can make multiple calls to RegisterRoutes for each of the service types. RegisterRoutes internally uses reflection to run through all the methods of the Handler, looking for CallbackMethod attributes and whether a RouteUrl is specified. If it is a new instance of a CallbackHandlerRouteHandler is created and the name of the method and the type are set. routes.Add(method.Name,           new Route(attr.RouteUrl, new CallbackHandlerRouteHandler(method.Name, typeof(TCallbackHandler) )) ); While the routing with CallbackHandlerRouteHandler is set up automatically for all methods that use the RouteUrl attribute, you can also use code to hook up those routes manually and skip using the attribute. The code for this is straightforward and just requires that you manually map each individual route to each method you want a routed: protected void Application_Start(objectsender, EventArgs e){    RegisterRoutes(RouteTable.Routes);}void RegisterRoutes(RouteCollection routes) { routes.Add("StockQuote Route",new Route("StockQuote/{symbol}",                     new CallbackHandlerRouteHandler("GetStockQuote",typeof(RestService) ) ) );     routes.Add("StockQuotes Route",new Route("StockQuotes/{symbolList}",                     new CallbackHandlerRouteHandler("GetStockQuotes",typeof(RestService) ) ) );}I think it’s clearly easier to have CallbackHandlerRouteHandler.RegisterRoutes() do this automatically for you based on RouteUrl attributes, but some people have a real aversion to attaching logic via attributes. Just realize that the option to manually create your routes is available as well. Using the RouteData in the Handler A RouteHandler’s responsibility is to create an HttpHandler and as mentioned earlier, natively IHttpHandler doesn’t have any support for RouteData. In order to utilize RouteData in your handler code you have to pass the RouteData to the handler. In my CallbackHandlerRouteHandler when it creates the HttpHandler instance it creates the instance and then assigns the custom RouteData property on the handler:IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; Again this only works if you actually add a RouteData property to your handler explicitly as I did in my CallbackHandler implementation:/// <summary> /// Optionally store RouteData on this handler /// so we can access it internally /// </summary> public RouteData RouteData {get; set; } and the RouteHandler needs to set it when it creates the handler instance. Once you have the route data in your handler you can access Route Keys and Values and also the RouteHandler. Since my RouteHandler has a custom property for the MethodName to retrieve it from within the handler I can do something like this now to retrieve the MethodName (this example is actually not in the handler but target is an instance pass to the processor): // check for Route Data method name if (target is CallbackHandler) { var routeData = ((CallbackHandler)target).RouteData; if (routeData != null) methodToCall = ((CallbackHandlerRouteHandler)routeData.RouteHandler).MethodName; } When I need to access the dynamic values in the route ( symbol in StockQuote/{symbol}) I can retrieve it easily with the Values collection (RouteData.Values["symbol"]). In my CallbackHandler processing logic I’m basically looking for matching parameter names to Route parameters: // look for parameters in the routeif(routeData != null){    string parmString = routeData.Values[parameter.Name] as string;    adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType);} And with that we’ve come full circle. We’ve created a custom RouteHandler() that passes the RouteData to the handler it creates. We’ve registered our routes to use the RouteHandler, and we’ve utilized the route data in our handler. For completeness sake here’s the routine that executes a method call based on the parameters passed in and one of the options is to retrieve the inbound parameters off RouteData (as well as from POST data or QueryString parameters):internal object ExecuteMethod(string method, object target, string[] parameters, CallbackMethodParameterType paramType, ref CallbackMethodAttribute callbackMethodAttribute) { HttpRequest Request = HttpContext.Current.Request; object Result = null; // Stores parsed parameters (from string JSON or QUeryString Values) object[] adjustedParms = null; Type PageType = target.GetType(); MethodInfo MI = PageType.GetMethod(method, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); if (MI == null) throw new InvalidOperationException("Invalid Server Method."); object[] methods = MI.GetCustomAttributes(typeof(CallbackMethodAttribute), false); if (methods.Length < 1) throw new InvalidOperationException("Server method is not accessible due to missing CallbackMethod attribute"); if (callbackMethodAttribute != null) callbackMethodAttribute = methods[0] as CallbackMethodAttribute; ParameterInfo[] parms = MI.GetParameters(); JSONSerializer serializer = new JSONSerializer(); RouteData routeData = null; if (target is CallbackHandler) routeData = ((CallbackHandler)target).RouteData; int parmCounter = 0; adjustedParms = new object[parms.Length]; foreach (ParameterInfo parameter in parms) { // Retrieve parameters out of QueryString or POST buffer if (parameters == null) { // look for parameters in the route if (routeData != null) { string parmString = routeData.Values[parameter.Name] as string; adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType); } // GET parameter are parsed as plain string values - no JSON encoding else if (HttpContext.Current.Request.HttpMethod == "GET") { // Look up the parameter by name string parmString = Request.QueryString[parameter.Name]; adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType); } // POST parameters are treated as methodParameters that are JSON encoded else if (paramType == CallbackMethodParameterType.Json) //string newVariable = methodParameters.GetValue(parmCounter) as string; adjustedParms[parmCounter] = serializer.Deserialize(Request.Params["parm" + (parmCounter + 1).ToString()], parameter.ParameterType); else adjustedParms[parmCounter] = SerializationUtils.DeSerializeObject( Request.Params["parm" + (parmCounter + 1).ToString()], parameter.ParameterType); } else if (paramType == CallbackMethodParameterType.Json) adjustedParms[parmCounter] = serializer.Deserialize(parameters[parmCounter], parameter.ParameterType); else adjustedParms[parmCounter] = SerializationUtils.DeSerializeObject(parameters[parmCounter], parameter.ParameterType); parmCounter++; } Result = MI.Invoke(target, adjustedParms); return Result; } The code basically uses Reflection to loop through all the parameters available on the method and tries to assign the parameters from RouteData, QueryString or POST variables. The parameters are converted into their appropriate types and then used to eventually make a Reflection based method call. What’s sweet is that the RouteData retrieval is just another option for dealing with the inbound data in this scenario and it adds exactly two lines of code plus the code to retrieve the MethodName I showed previously – a seriously low impact addition that adds a lot of extra value to this endpoint callback processing implementation. Debugging your Routes If you create a lot of routes it’s easy to run into Route conflicts where multiple routes have the same path and overlap with each other. This can be difficult to debug especially if you are using automatically generated routes like the routes created by CallbackHandlerRouteHandler.RegisterRoutes. Luckily there’s a tool that can help you out with this nicely. Phill Haack created a RouteDebugging tool you can download and add to your project. The easiest way to do this is to grab and add this to your project is to use NuGet (Add Library Package from your Project’s Reference Nodes):   which adds a RouteDebug assembly to your project. Once installed you can easily debug your routes with this simple line of code which needs to be installed at application startup:protected void Application_Start(object sender, EventArgs e) { CallbackHandlerRouteHandler.RegisterRoutes<StockService>(RouteTable.Routes); // Debug your routes RouteDebug.RouteDebugger.RewriteRoutesForTesting(RouteTable.Routes); } Any routed URL then displays something like this: The screen shows you your current route data and all the routes that are mapped along with a flag that displays which route was actually matched. This is useful – if you have any overlap of routes you will be able to see which routes are triggered – the first one in the sequence wins. This tool has saved my ass on a few occasions – and with NuGet now it’s easy to add it to your project in a few seconds and then remove it when you’re done. Routing Around Custom routing seems slightly complicated on first blush due to its disconnected components of RouteHandler, route registration and mapping of custom handlers. But once you understand the relationship between a RouteHandler, the RouteData and how to pass it to a handler, utilizing of Routing becomes a lot easier as you can easily pass context from the registration to the RouteHandler and through to the HttpHandler. The most important thing to understand when building custom routing solutions is to figure out how to map URLs in such a way that the handler can figure out all the pieces it needs to process the request. This can be via URL routing parameters and as I did in my example by passing additional context information as part of the RouteHandler instance that provides the proper execution context. In my case this ‘context’ was the method name, but it could be an actual static value like an enum identifying an operation or category in an application. Basically user supplied data comes in through the url and static application internal data can be passed via RouteHandler property values. Routing can make your application URLs easier to read by non-techie types regardless of whether you’re building Service type or REST applications, or full on Web interfaces. Routing in ASP.NET 4.0 makes it possible to create just about any extensionless URLs you can dream up and custom RouteHanmdler References Sample ProjectIncludes the sample CallbackHandler service discussed here along with compiled versionsof the Westwind.Web and Westwind.Utilities assemblies.  (requires .NET 4.0/VS 2010) West Wind Web Toolkit includes full implementation of CallbackHandler and the Routing Handler West Wind Web Toolkit Source CodeContains the full source code to the Westwind.Web and Westwind.Utilities assemblies usedin these samples. Includes the source described in the post.(Latest build in the Subversion Repository) CallbackHandler Source(Relevant code to this article tree in Westwind.Web assembly) JSONView FireFoxPluginA simple FireFox Plugin to easily view JSON data natively in FireFox.For IE you can use a registry hack to display JSON as raw text.© Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  AJAX  HTTP  

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  • Introduction to the ASP.NET Web API

    - by Stephen.Walther
    I am a huge fan of Ajax. If you want to create a great experience for the users of your website – regardless of whether you are building an ASP.NET MVC or an ASP.NET Web Forms site — then you need to use Ajax. Otherwise, you are just being cruel to your customers. We use Ajax extensively in several of the ASP.NET applications that my company, Superexpert.com, builds. We expose data from the server as JSON and use jQuery to retrieve and update that data from the browser. One challenge, when building an ASP.NET website, is deciding on which technology to use to expose JSON data from the server. For example, how do you expose a list of products from the server as JSON so you can retrieve the list of products with jQuery? You have a number of options (too many options) including ASMX Web services, WCF Web Services, ASHX Generic Handlers, WCF Data Services, and MVC controller actions. Fortunately, the world has just been simplified. With the release of ASP.NET 4 Beta, Microsoft has introduced a new technology for exposing JSON from the server named the ASP.NET Web API. You can use the ASP.NET Web API with both ASP.NET MVC and ASP.NET Web Forms applications. The goal of this blog post is to provide you with a brief overview of the features of the new ASP.NET Web API. You learn how to use the ASP.NET Web API to retrieve, insert, update, and delete database records with jQuery. We also discuss how you can perform form validation when using the Web API and use OData when using the Web API. Creating an ASP.NET Web API Controller The ASP.NET Web API exposes JSON data through a new type of controller called an API controller. You can add an API controller to an existing ASP.NET MVC 4 project through the standard Add Controller dialog box. Right-click your Controllers folder and select Add, Controller. In the dialog box, name your controller MovieController and select the Empty API controller template: A brand new API controller looks like this: using System; using System.Collections.Generic; using System.Linq; using System.Net.Http; using System.Web.Http; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { } } An API controller, unlike a standard MVC controller, derives from the base ApiController class instead of the base Controller class. Using jQuery to Retrieve, Insert, Update, and Delete Data Let’s create an Ajaxified Movie Database application. We’ll retrieve, insert, update, and delete movies using jQuery with the MovieController which we just created. Our Movie model class looks like this: namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } public string Title { get; set; } public string Director { get; set; } } } Our application will consist of a single HTML page named Movies.html. We’ll place all of our jQuery code in the Movies.html page. Getting a Single Record with the ASP.NET Web API To support retrieving a single movie from the server, we need to add a Get method to our API controller: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public Movie GetMovie(int id) { // Return movie by id if (id == 1) { return new Movie { Id = 1, Title = "Star Wars", Director = "Lucas" }; } // Otherwise, movie was not found throw new HttpResponseException(HttpStatusCode.NotFound); } } } In the code above, the GetMovie() method accepts the Id of a movie. If the Id has the value 1 then the method returns the movie Star Wars. Otherwise, the method throws an exception and returns 404 Not Found HTTP status code. After building your project, you can invoke the MovieController.GetMovie() method by entering the following URL in your web browser address bar: http://localhost:[port]/api/movie/1 (You’ll need to enter the correct randomly generated port). In the URL api/movie/1, the first “api” segment indicates that this is a Web API route. The “movie” segment indicates that the MovieController should be invoked. You do not specify the name of the action. Instead, the HTTP method used to make the request – GET, POST, PUT, DELETE — is used to identify the action to invoke. The ASP.NET Web API uses different routing conventions than normal ASP.NET MVC controllers. When you make an HTTP GET request then any API controller method with a name that starts with “GET” is invoked. So, we could have called our API controller action GetPopcorn() instead of GetMovie() and it would still be invoked by the URL api/movie/1. The default route for the Web API is defined in the Global.asax file and it looks like this: routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { id = RouteParameter.Optional } ); We can invoke our GetMovie() controller action with the jQuery code in the following HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Get Movie</title> </head> <body> <div> Title: <span id="title"></span> </div> <div> Director: <span id="director"></span> </div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> getMovie(1, function (movie) { $("#title").html(movie.Title); $("#director").html(movie.Director); }); function getMovie(id, callback) { $.ajax({ url: "/api/Movie", data: { id: id }, type: "GET", contentType: "application/json;charset=utf-8", statusCode: { 200: function (movie) { callback(movie); }, 404: function () { alert("Not Found!"); } } }); } </script> </body> </html> In the code above, the jQuery $.ajax() method is used to invoke the GetMovie() method. Notice that the Ajax call handles two HTTP response codes. When the GetMove() method successfully returns a movie, the method returns a 200 status code. In that case, the details of the movie are displayed in the HTML page. Otherwise, if the movie is not found, the GetMovie() method returns a 404 status code. In that case, the page simply displays an alert box indicating that the movie was not found (hopefully, you would implement something more graceful in an actual application). You can use your browser’s Developer Tools to see what is going on in the background when you open the HTML page (hit F12 in the most recent version of most browsers). For example, you can use the Network tab in Google Chrome to see the Ajax request which invokes the GetMovie() method: Getting a Set of Records with the ASP.NET Web API Let’s modify our Movie API controller so that it returns a collection of movies. The following Movie controller has a new ListMovies() method which returns a (hard-coded) collection of movies: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public IEnumerable<Movie> ListMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=1, Title="King Kong", Director="Jackson"}, new Movie {Id=1, Title="Memento", Director="Nolan"} }; } } } Because we named our action ListMovies(), the default Web API route will never match it. Therefore, we need to add the following custom route to our Global.asax file (at the top of the RegisterRoutes() method): routes.MapHttpRoute( name: "ActionApi", routeTemplate: "api/{controller}/{action}/{id}", defaults: new { id = RouteParameter.Optional } ); This route enables us to invoke the ListMovies() method with the URL /api/movie/listmovies. Now that we have exposed our collection of movies from the server, we can retrieve and display the list of movies using jQuery in our HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>List Movies</title> </head> <body> <div id="movies"></div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> listMovies(function (movies) { var strMovies=""; $.each(movies, function (index, movie) { strMovies += "<div>" + movie.Title + "</div>"; }); $("#movies").html(strMovies); }); function listMovies(callback) { $.ajax({ url: "/api/Movie/ListMovies", data: {}, type: "GET", contentType: "application/json;charset=utf-8", }).then(function(movies){ callback(movies); }); } </script> </body> </html>     Inserting a Record with the ASP.NET Web API Now let’s modify our Movie API controller so it supports creating new records: public HttpResponseMessage<Movie> PostMovie(Movie movieToCreate) { // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } The PostMovie() method in the code above accepts a movieToCreate parameter. We don’t actually store the new movie anywhere. In real life, you will want to call a service method to store the new movie in a database. When you create a new resource, such as a new movie, you should return the location of the new resource. In the code above, the URL where the new movie can be retrieved is assigned to the Location header returned in the PostMovie() response. Because the name of our method starts with “Post”, we don’t need to create a custom route. The PostMovie() method can be invoked with the URL /Movie/PostMovie – just as long as the method is invoked within the context of a HTTP POST request. The following HTML page invokes the PostMovie() method. <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "Jackson" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }); function createMovie(movieToCreate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); } </script> </body> </html> This page creates a new movie (the Hobbit) by calling the createMovie() method. The page simply displays the Id of the new movie: The HTTP Post operation is performed with the following call to the jQuery $.ajax() method: $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); Notice that the type of Ajax request is a POST request. This is required to match the PostMovie() method. Notice, furthermore, that the new movie is converted into JSON using JSON.stringify(). The JSON.stringify() method takes a JavaScript object and converts it into a JSON string. Finally, notice that success is represented with a 201 status code. The HttpStatusCode.Created value returned from the PostMovie() method returns a 201 status code. Updating a Record with the ASP.NET Web API Here’s how we can modify the Movie API controller to support updating an existing record. In this case, we need to create a PUT method to handle an HTTP PUT request: public void PutMovie(Movie movieToUpdate) { if (movieToUpdate.Id == 1) { // Update the movie in the database return; } // If you can't find the movie to update throw new HttpResponseException(HttpStatusCode.NotFound); } Unlike our PostMovie() method, the PutMovie() method does not return a result. The action either updates the database or, if the movie cannot be found, returns an HTTP Status code of 404. The following HTML page illustrates how you can invoke the PutMovie() method: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Put Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToUpdate = { id: 1, title: "The Hobbit", director: "Jackson" }; updateMovie(movieToUpdate, function () { alert("Movie updated!"); }); function updateMovie(movieToUpdate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToUpdate), type: "PUT", contentType: "application/json;charset=utf-8", statusCode: { 200: function () { callback(); }, 404: function () { alert("Movie not found!"); } } }); } </script> </body> </html> Deleting a Record with the ASP.NET Web API Here’s the code for deleting a movie: public HttpResponseMessage DeleteMovie(int id) { // Delete the movie from the database // Return status code return new HttpResponseMessage(HttpStatusCode.NoContent); } This method simply deletes the movie (well, not really, but pretend that it does) and returns a No Content status code (204). The following page illustrates how you can invoke the DeleteMovie() action: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Delete Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> deleteMovie(1, function () { alert("Movie deleted!"); }); function deleteMovie(id, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify({id:id}), type: "DELETE", contentType: "application/json;charset=utf-8", statusCode: { 204: function () { callback(); } } }); } </script> </body> </html> Performing Validation How do you perform form validation when using the ASP.NET Web API? Because validation in ASP.NET MVC is driven by the Default Model Binder, and because the Web API uses the Default Model Binder, you get validation for free. Let’s modify our Movie class so it includes some of the standard validation attributes: using System.ComponentModel.DataAnnotations; namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } [Required(ErrorMessage="Title is required!")] [StringLength(5, ErrorMessage="Title cannot be more than 5 characters!")] public string Title { get; set; } [Required(ErrorMessage="Director is required!")] public string Director { get; set; } } } In the code above, the Required validation attribute is used to make both the Title and Director properties required. The StringLength attribute is used to require the length of the movie title to be no more than 5 characters. Now let’s modify our PostMovie() action to validate a movie before adding the movie to the database: public HttpResponseMessage PostMovie(Movie movieToCreate) { // Validate movie if (!ModelState.IsValid) { var errors = new JsonArray(); foreach (var prop in ModelState.Values) { if (prop.Errors.Any()) { errors.Add(prop.Errors.First().ErrorMessage); } } return new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } If ModelState.IsValid has the value false then the errors in model state are copied to a new JSON array. Each property – such as the Title and Director property — can have multiple errors. In the code above, only the first error message is copied over. The JSON array is returned with a Bad Request status code (400 status code). The following HTML page illustrates how you can invoke our modified PostMovie() action and display any error messages: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }, function (errors) { var strErrors = ""; $.each(errors, function(index, err) { strErrors += "*" + err + "\n"; }); alert(strErrors); } ); function createMovie(movieToCreate, success, fail) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToCreate), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { success(newMovie); }, 400: function (xhr) { var errors = JSON.parse(xhr.responseText); fail(errors); } } }); } </script> </body> </html> The createMovie() function performs an Ajax request and handles either a 201 or a 400 status code from the response. If a 201 status code is returned then there were no validation errors and the new movie was created. If, on the other hand, a 400 status code is returned then there was a validation error. The validation errors are retrieved from the XmlHttpRequest responseText property. The error messages are displayed in an alert: (Please don’t use JavaScript alert dialogs to display validation errors, I just did it this way out of pure laziness) This validation code in our PostMovie() method is pretty generic. There is nothing specific about this code to the PostMovie() method. In the following video, Jon Galloway demonstrates how to create a global Validation filter which can be used with any API controller action: http://www.asp.net/web-api/overview/web-api-routing-and-actions/video-custom-validation His validation filter looks like this: using System.Json; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http.Controllers; using System.Web.Http.Filters; namespace MyWebAPIApp.Filters { public class ValidationActionFilter:ActionFilterAttribute { public override void OnActionExecuting(HttpActionContext actionContext) { var modelState = actionContext.ModelState; if (!modelState.IsValid) { dynamic errors = new JsonObject(); foreach (var key in modelState.Keys) { var state = modelState[key]; if (state.Errors.Any()) { errors[key] = state.Errors.First().ErrorMessage; } } actionContext.Response = new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } } } } And you can register the validation filter in the Application_Start() method in the Global.asax file like this: GlobalConfiguration.Configuration.Filters.Add(new ValidationActionFilter()); After you register the Validation filter, validation error messages are returned from any API controller action method automatically when validation fails. You don’t need to add any special logic to any of your API controller actions to take advantage of the filter. Querying using OData The OData protocol is an open protocol created by Microsoft which enables you to perform queries over the web. The official website for OData is located here: http://odata.org For example, here are some of the query options which you can use with OData: · $orderby – Enables you to retrieve results in a certain order. · $top – Enables you to retrieve a certain number of results. · $skip – Enables you to skip over a certain number of results (use with $top for paging). · $filter – Enables you to filter the results returned. The ASP.NET Web API supports a subset of the OData protocol. You can use all of the query options listed above when interacting with an API controller. The only requirement is that the API controller action returns its data as IQueryable. For example, the following Movie controller has an action named GetMovies() which returns an IQueryable of movies: public IQueryable<Movie> GetMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=2, Title="King Kong", Director="Jackson"}, new Movie {Id=3, Title="Willow", Director="Lucas"}, new Movie {Id=4, Title="Shrek", Director="Smith"}, new Movie {Id=5, Title="Memento", Director="Nolan"} }.AsQueryable(); } If you enter the following URL in your browser: /api/movie?$top=2&$orderby=Title Then you will limit the movies returned to the top 2 in order of the movie Title. You will get the following results: By using the $top option in combination with the $skip option, you can enable client-side paging. For example, you can use $top and $skip to page through thousands of products, 10 products at a time. The $filter query option is very powerful. You can use this option to filter the results from a query. Here are some examples: Return every movie directed by Lucas: /api/movie?$filter=Director eq ‘Lucas’ Return every movie which has a title which starts with ‘S’: /api/movie?$filter=startswith(Title,’S') Return every movie which has an Id greater than 2: /api/movie?$filter=Id gt 2 The complete documentation for the $filter option is located here: http://www.odata.org/developers/protocols/uri-conventions#FilterSystemQueryOption Summary The goal of this blog entry was to provide you with an overview of the new ASP.NET Web API introduced with the Beta release of ASP.NET 4. In this post, I discussed how you can retrieve, insert, update, and delete data by using jQuery with the Web API. I also discussed how you can use the standard validation attributes with the Web API. You learned how to return validation error messages to the client and display the error messages using jQuery. Finally, we briefly discussed how the ASP.NET Web API supports the OData protocol. For example, you learned how to filter records returned from an API controller action by using the $filter query option. I’m excited about the new Web API. This is a feature which I expect to use with almost every ASP.NET application which I build in the future.

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  • Introduction to the ASP.NET Web API

    - by Stephen.Walther
    I am a huge fan of Ajax. If you want to create a great experience for the users of your website – regardless of whether you are building an ASP.NET MVC or an ASP.NET Web Forms site — then you need to use Ajax. Otherwise, you are just being cruel to your customers. We use Ajax extensively in several of the ASP.NET applications that my company, Superexpert.com, builds. We expose data from the server as JSON and use jQuery to retrieve and update that data from the browser. One challenge, when building an ASP.NET website, is deciding on which technology to use to expose JSON data from the server. For example, how do you expose a list of products from the server as JSON so you can retrieve the list of products with jQuery? You have a number of options (too many options) including ASMX Web services, WCF Web Services, ASHX Generic Handlers, WCF Data Services, and MVC controller actions. Fortunately, the world has just been simplified. With the release of ASP.NET 4 Beta, Microsoft has introduced a new technology for exposing JSON from the server named the ASP.NET Web API. You can use the ASP.NET Web API with both ASP.NET MVC and ASP.NET Web Forms applications. The goal of this blog post is to provide you with a brief overview of the features of the new ASP.NET Web API. You learn how to use the ASP.NET Web API to retrieve, insert, update, and delete database records with jQuery. We also discuss how you can perform form validation when using the Web API and use OData when using the Web API. Creating an ASP.NET Web API Controller The ASP.NET Web API exposes JSON data through a new type of controller called an API controller. You can add an API controller to an existing ASP.NET MVC 4 project through the standard Add Controller dialog box. Right-click your Controllers folder and select Add, Controller. In the dialog box, name your controller MovieController and select the Empty API controller template: A brand new API controller looks like this: using System; using System.Collections.Generic; using System.Linq; using System.Net.Http; using System.Web.Http; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { } } An API controller, unlike a standard MVC controller, derives from the base ApiController class instead of the base Controller class. Using jQuery to Retrieve, Insert, Update, and Delete Data Let’s create an Ajaxified Movie Database application. We’ll retrieve, insert, update, and delete movies using jQuery with the MovieController which we just created. Our Movie model class looks like this: namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } public string Title { get; set; } public string Director { get; set; } } } Our application will consist of a single HTML page named Movies.html. We’ll place all of our jQuery code in the Movies.html page. Getting a Single Record with the ASP.NET Web API To support retrieving a single movie from the server, we need to add a Get method to our API controller: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public Movie GetMovie(int id) { // Return movie by id if (id == 1) { return new Movie { Id = 1, Title = "Star Wars", Director = "Lucas" }; } // Otherwise, movie was not found throw new HttpResponseException(HttpStatusCode.NotFound); } } } In the code above, the GetMovie() method accepts the Id of a movie. If the Id has the value 1 then the method returns the movie Star Wars. Otherwise, the method throws an exception and returns 404 Not Found HTTP status code. After building your project, you can invoke the MovieController.GetMovie() method by entering the following URL in your web browser address bar: http://localhost:[port]/api/movie/1 (You’ll need to enter the correct randomly generated port). In the URL api/movie/1, the first “api” segment indicates that this is a Web API route. The “movie” segment indicates that the MovieController should be invoked. You do not specify the name of the action. Instead, the HTTP method used to make the request – GET, POST, PUT, DELETE — is used to identify the action to invoke. The ASP.NET Web API uses different routing conventions than normal ASP.NET MVC controllers. When you make an HTTP GET request then any API controller method with a name that starts with “GET” is invoked. So, we could have called our API controller action GetPopcorn() instead of GetMovie() and it would still be invoked by the URL api/movie/1. The default route for the Web API is defined in the Global.asax file and it looks like this: routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { id = RouteParameter.Optional } ); We can invoke our GetMovie() controller action with the jQuery code in the following HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Get Movie</title> </head> <body> <div> Title: <span id="title"></span> </div> <div> Director: <span id="director"></span> </div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> getMovie(1, function (movie) { $("#title").html(movie.Title); $("#director").html(movie.Director); }); function getMovie(id, callback) { $.ajax({ url: "/api/Movie", data: { id: id }, type: "GET", contentType: "application/json;charset=utf-8", statusCode: { 200: function (movie) { callback(movie); }, 404: function () { alert("Not Found!"); } } }); } </script> </body> </html> In the code above, the jQuery $.ajax() method is used to invoke the GetMovie() method. Notice that the Ajax call handles two HTTP response codes. When the GetMove() method successfully returns a movie, the method returns a 200 status code. In that case, the details of the movie are displayed in the HTML page. Otherwise, if the movie is not found, the GetMovie() method returns a 404 status code. In that case, the page simply displays an alert box indicating that the movie was not found (hopefully, you would implement something more graceful in an actual application). You can use your browser’s Developer Tools to see what is going on in the background when you open the HTML page (hit F12 in the most recent version of most browsers). For example, you can use the Network tab in Google Chrome to see the Ajax request which invokes the GetMovie() method: Getting a Set of Records with the ASP.NET Web API Let’s modify our Movie API controller so that it returns a collection of movies. The following Movie controller has a new ListMovies() method which returns a (hard-coded) collection of movies: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using MyWebAPIApp.Models; namespace MyWebAPIApp.Controllers { public class MovieController : ApiController { public IEnumerable<Movie> ListMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=1, Title="King Kong", Director="Jackson"}, new Movie {Id=1, Title="Memento", Director="Nolan"} }; } } } Because we named our action ListMovies(), the default Web API route will never match it. Therefore, we need to add the following custom route to our Global.asax file (at the top of the RegisterRoutes() method): routes.MapHttpRoute( name: "ActionApi", routeTemplate: "api/{controller}/{action}/{id}", defaults: new { id = RouteParameter.Optional } ); This route enables us to invoke the ListMovies() method with the URL /api/movie/listmovies. Now that we have exposed our collection of movies from the server, we can retrieve and display the list of movies using jQuery in our HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>List Movies</title> </head> <body> <div id="movies"></div> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> listMovies(function (movies) { var strMovies=""; $.each(movies, function (index, movie) { strMovies += "<div>" + movie.Title + "</div>"; }); $("#movies").html(strMovies); }); function listMovies(callback) { $.ajax({ url: "/api/Movie/ListMovies", data: {}, type: "GET", contentType: "application/json;charset=utf-8", }).then(function(movies){ callback(movies); }); } </script> </body> </html>     Inserting a Record with the ASP.NET Web API Now let’s modify our Movie API controller so it supports creating new records: public HttpResponseMessage<Movie> PostMovie(Movie movieToCreate) { // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } The PostMovie() method in the code above accepts a movieToCreate parameter. We don’t actually store the new movie anywhere. In real life, you will want to call a service method to store the new movie in a database. When you create a new resource, such as a new movie, you should return the location of the new resource. In the code above, the URL where the new movie can be retrieved is assigned to the Location header returned in the PostMovie() response. Because the name of our method starts with “Post”, we don’t need to create a custom route. The PostMovie() method can be invoked with the URL /Movie/PostMovie – just as long as the method is invoked within the context of a HTTP POST request. The following HTML page invokes the PostMovie() method. <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "Jackson" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }); function createMovie(movieToCreate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); } </script> </body> </html> This page creates a new movie (the Hobbit) by calling the createMovie() method. The page simply displays the Id of the new movie: The HTTP Post operation is performed with the following call to the jQuery $.ajax() method: $.ajax({ url: "/api/Movie", data: JSON.stringify( movieToCreate ), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { callback(newMovie); } } }); Notice that the type of Ajax request is a POST request. This is required to match the PostMovie() method. Notice, furthermore, that the new movie is converted into JSON using JSON.stringify(). The JSON.stringify() method takes a JavaScript object and converts it into a JSON string. Finally, notice that success is represented with a 201 status code. The HttpStatusCode.Created value returned from the PostMovie() method returns a 201 status code. Updating a Record with the ASP.NET Web API Here’s how we can modify the Movie API controller to support updating an existing record. In this case, we need to create a PUT method to handle an HTTP PUT request: public void PutMovie(Movie movieToUpdate) { if (movieToUpdate.Id == 1) { // Update the movie in the database return; } // If you can't find the movie to update throw new HttpResponseException(HttpStatusCode.NotFound); } Unlike our PostMovie() method, the PutMovie() method does not return a result. The action either updates the database or, if the movie cannot be found, returns an HTTP Status code of 404. The following HTML page illustrates how you can invoke the PutMovie() method: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Put Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToUpdate = { id: 1, title: "The Hobbit", director: "Jackson" }; updateMovie(movieToUpdate, function () { alert("Movie updated!"); }); function updateMovie(movieToUpdate, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToUpdate), type: "PUT", contentType: "application/json;charset=utf-8", statusCode: { 200: function () { callback(); }, 404: function () { alert("Movie not found!"); } } }); } </script> </body> </html> Deleting a Record with the ASP.NET Web API Here’s the code for deleting a movie: public HttpResponseMessage DeleteMovie(int id) { // Delete the movie from the database // Return status code return new HttpResponseMessage(HttpStatusCode.NoContent); } This method simply deletes the movie (well, not really, but pretend that it does) and returns a No Content status code (204). The following page illustrates how you can invoke the DeleteMovie() action: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Delete Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> deleteMovie(1, function () { alert("Movie deleted!"); }); function deleteMovie(id, callback) { $.ajax({ url: "/api/Movie", data: JSON.stringify({id:id}), type: "DELETE", contentType: "application/json;charset=utf-8", statusCode: { 204: function () { callback(); } } }); } </script> </body> </html> Performing Validation How do you perform form validation when using the ASP.NET Web API? Because validation in ASP.NET MVC is driven by the Default Model Binder, and because the Web API uses the Default Model Binder, you get validation for free. Let’s modify our Movie class so it includes some of the standard validation attributes: using System.ComponentModel.DataAnnotations; namespace MyWebAPIApp.Models { public class Movie { public int Id { get; set; } [Required(ErrorMessage="Title is required!")] [StringLength(5, ErrorMessage="Title cannot be more than 5 characters!")] public string Title { get; set; } [Required(ErrorMessage="Director is required!")] public string Director { get; set; } } } In the code above, the Required validation attribute is used to make both the Title and Director properties required. The StringLength attribute is used to require the length of the movie title to be no more than 5 characters. Now let’s modify our PostMovie() action to validate a movie before adding the movie to the database: public HttpResponseMessage PostMovie(Movie movieToCreate) { // Validate movie if (!ModelState.IsValid) { var errors = new JsonArray(); foreach (var prop in ModelState.Values) { if (prop.Errors.Any()) { errors.Add(prop.Errors.First().ErrorMessage); } } return new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } // Add movieToCreate to the database and update primary key movieToCreate.Id = 23; // Build a response that contains the location of the new movie var response = new HttpResponseMessage<Movie>(movieToCreate, HttpStatusCode.Created); var relativePath = "/api/movie/" + movieToCreate.Id; response.Headers.Location = new Uri(Request.RequestUri, relativePath); return response; } If ModelState.IsValid has the value false then the errors in model state are copied to a new JSON array. Each property – such as the Title and Director property — can have multiple errors. In the code above, only the first error message is copied over. The JSON array is returned with a Bad Request status code (400 status code). The following HTML page illustrates how you can invoke our modified PostMovie() action and display any error messages: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Create Movie</title> </head> <body> <script type="text/javascript" src="Scripts/jquery-1.6.2.min.js"></script> <script type="text/javascript"> var movieToCreate = { title: "The Hobbit", director: "" }; createMovie(movieToCreate, function (newMovie) { alert("New movie created with an Id of " + newMovie.Id); }, function (errors) { var strErrors = ""; $.each(errors, function(index, err) { strErrors += "*" + err + "n"; }); alert(strErrors); } ); function createMovie(movieToCreate, success, fail) { $.ajax({ url: "/api/Movie", data: JSON.stringify(movieToCreate), type: "POST", contentType: "application/json;charset=utf-8", statusCode: { 201: function (newMovie) { success(newMovie); }, 400: function (xhr) { var errors = JSON.parse(xhr.responseText); fail(errors); } } }); } </script> </body> </html> The createMovie() function performs an Ajax request and handles either a 201 or a 400 status code from the response. If a 201 status code is returned then there were no validation errors and the new movie was created. If, on the other hand, a 400 status code is returned then there was a validation error. The validation errors are retrieved from the XmlHttpRequest responseText property. The error messages are displayed in an alert: (Please don’t use JavaScript alert dialogs to display validation errors, I just did it this way out of pure laziness) This validation code in our PostMovie() method is pretty generic. There is nothing specific about this code to the PostMovie() method. In the following video, Jon Galloway demonstrates how to create a global Validation filter which can be used with any API controller action: http://www.asp.net/web-api/overview/web-api-routing-and-actions/video-custom-validation His validation filter looks like this: using System.Json; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http.Controllers; using System.Web.Http.Filters; namespace MyWebAPIApp.Filters { public class ValidationActionFilter:ActionFilterAttribute { public override void OnActionExecuting(HttpActionContext actionContext) { var modelState = actionContext.ModelState; if (!modelState.IsValid) { dynamic errors = new JsonObject(); foreach (var key in modelState.Keys) { var state = modelState[key]; if (state.Errors.Any()) { errors[key] = state.Errors.First().ErrorMessage; } } actionContext.Response = new HttpResponseMessage<JsonValue>(errors, HttpStatusCode.BadRequest); } } } } And you can register the validation filter in the Application_Start() method in the Global.asax file like this: GlobalConfiguration.Configuration.Filters.Add(new ValidationActionFilter()); After you register the Validation filter, validation error messages are returned from any API controller action method automatically when validation fails. You don’t need to add any special logic to any of your API controller actions to take advantage of the filter. Querying using OData The OData protocol is an open protocol created by Microsoft which enables you to perform queries over the web. The official website for OData is located here: http://odata.org For example, here are some of the query options which you can use with OData: · $orderby – Enables you to retrieve results in a certain order. · $top – Enables you to retrieve a certain number of results. · $skip – Enables you to skip over a certain number of results (use with $top for paging). · $filter – Enables you to filter the results returned. The ASP.NET Web API supports a subset of the OData protocol. You can use all of the query options listed above when interacting with an API controller. The only requirement is that the API controller action returns its data as IQueryable. For example, the following Movie controller has an action named GetMovies() which returns an IQueryable of movies: public IQueryable<Movie> GetMovies() { return new List<Movie> { new Movie {Id=1, Title="Star Wars", Director="Lucas"}, new Movie {Id=2, Title="King Kong", Director="Jackson"}, new Movie {Id=3, Title="Willow", Director="Lucas"}, new Movie {Id=4, Title="Shrek", Director="Smith"}, new Movie {Id=5, Title="Memento", Director="Nolan"} }.AsQueryable(); } If you enter the following URL in your browser: /api/movie?$top=2&$orderby=Title Then you will limit the movies returned to the top 2 in order of the movie Title. You will get the following results: By using the $top option in combination with the $skip option, you can enable client-side paging. For example, you can use $top and $skip to page through thousands of products, 10 products at a time. The $filter query option is very powerful. You can use this option to filter the results from a query. Here are some examples: Return every movie directed by Lucas: /api/movie?$filter=Director eq ‘Lucas’ Return every movie which has a title which starts with ‘S’: /api/movie?$filter=startswith(Title,’S') Return every movie which has an Id greater than 2: /api/movie?$filter=Id gt 2 The complete documentation for the $filter option is located here: http://www.odata.org/developers/protocols/uri-conventions#FilterSystemQueryOption Summary The goal of this blog entry was to provide you with an overview of the new ASP.NET Web API introduced with the Beta release of ASP.NET 4. In this post, I discussed how you can retrieve, insert, update, and delete data by using jQuery with the Web API. I also discussed how you can use the standard validation attributes with the Web API. You learned how to return validation error messages to the client and display the error messages using jQuery. Finally, we briefly discussed how the ASP.NET Web API supports the OData protocol. For example, you learned how to filter records returned from an API controller action by using the $filter query option. I’m excited about the new Web API. This is a feature which I expect to use with almost every ASP.NET application which I build in the future.

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  • What&rsquo;s New in ASP.NET 4.0 Part Two: WebForms and Visual Studio Enhancements

    - by Rick Strahl
    In the last installment I talked about the core changes in the ASP.NET runtime that I’ve been taking advantage of. In this column, I’ll cover the changes to the Web Forms engine and some of the cool improvements in Visual Studio that make Web and general development easier. WebForms The WebForms engine is the area that has received most significant changes in ASP.NET 4.0. Probably the most widely anticipated features are related to managing page client ids and of ViewState on WebForm pages. Take Control of Your ClientIDs Unique ClientID generation in ASP.NET has been one of the most complained about “features” in ASP.NET. Although there’s a very good technical reason for these unique generated ids - they guarantee unique ids for each and every server control on a page - these unique and generated ids often get in the way of client-side JavaScript development and CSS styling as it’s often inconvenient and fragile to work with the long, generated ClientIDs. In ASP.NET 4.0 you can now specify an explicit client id mode on each control or each naming container parent control to control how client ids are generated. By default, ASP.NET generates mangled client ids for any control contained in a naming container (like a Master Page, or a User Control for example). The key to ClientID management in ASP.NET 4.0 are the new ClientIDMode and ClientIDRowSuffix properties. ClientIDMode supports four different ClientID generation settings shown below. For the following examples, imagine that you have a Textbox control named txtName inside of a master page control container on a WebForms page. <%@Page Language="C#"      MasterPageFile="~/Site.Master"     CodeBehind="WebForm2.aspx.cs"     Inherits="WebApplication1.WebForm2"  %> <asp:Content ID="content"  ContentPlaceHolderID="content"               runat="server"               ClientIDMode="Static" >       <asp:TextBox runat="server" ID="txtName" /> </asp:Content> The four available ClientIDMode values are: AutoID This is the existing behavior in ASP.NET 1.x-3.x where full naming container munging takes place. <input name="ctl00$content$txtName" type="text"        id="ctl00_content_txtName" /> This should be familiar to any ASP.NET developer and results in fairly unpredictable client ids that can easily change if the containership hierarchy changes. For example, removing the master page changes the name in this case, so if you were to move a block of script code that works against the control to a non-Master page, the script code immediately breaks. Static This option is the most deterministic setting that forces the control’s ClientID to use its ID value directly. No naming container naming at all is applied and you end up with clean client ids: <input name="ctl00$content$txtName"         type="text" id="txtName" /> Note that the name property which is used for postback variables to the server still is munged, but the ClientID property is displayed simply as the ID value that you have assigned to the control. This option is what most of us want to use, but you have to be clear on that because it can potentially cause conflicts with other controls on the page. If there are several instances of the same naming container (several instances of the same user control for example) there can easily be a client id naming conflict. Note that if you assign Static to a data-bound control, like a list child control in templates, you do not get unique ids either, so for list controls where you rely on unique id for child controls, you’ll probably want to use Predictable rather than Static. I’ll write more on this a little later when I discuss ClientIDRowSuffix. Predictable The previous two values are pretty self-explanatory. Predictable however, requires some explanation. To me at least it’s not in the least bit predictable. MSDN defines this value as follows: This algorithm is used for controls that are in data-bound controls. The ClientID value is generated by concatenating the ClientID value of the parent naming container with the ID value of the control. If the control is a data-bound control that generates multiple rows, the value of the data field specified in the ClientIDRowSuffix property is added at the end. For the GridView control, multiple data fields can be specified. If the ClientIDRowSuffix property is blank, a sequential number is added at the end instead of a data-field value. Each segment is separated by an underscore character (_). The key that makes this value a bit confusing is that it relies on the parent NamingContainer’s ClientID to build its own ClientID value. This effectively means that the value is not predictable at all but rather very tightly coupled to the parent naming container’s ClientIDMode setting. For my simple textbox example, if the ClientIDMode property of the parent naming container (Page in this case) is set to “Predictable” you’ll get this: <input name="ctl00$content$txtName" type="text"         id="content_txtName" /> which gives an id that based on walking up to the currently active naming container (the MasterPage content container) and starting the id formatting from there downward. Think of this as a semi unique name that’s guaranteed unique only for the naming container. If, on the other hand, the Page is set to “AutoID” you get the following with Predictable on txtName: <input name="ctl00$content$txtName" type="text"         id="ctl00_content_txtName" /> The latter is effectively the same as if you specified AutoID because it inherits the AutoID naming from the Page and Content Master Page control of the page. But again - predictable behavior always depends on the parent naming container and how it generates its id, so the id may not always be exactly the same as the AutoID generated value because somewhere in the NamingContainer chain the ClientIDMode setting may be set to a different value. For example, if you had another naming container in the middle that was set to Static you’d end up effectively with an id that starts with the NamingContainers id rather than the whole ctl000_content munging. The most common use for Predictable is likely to be for data-bound controls, which results in each data bound item getting a unique ClientID. Unfortunately, even here the behavior can be very unpredictable depending on which data-bound control you use - I found significant differences in how template controls in a GridView behave from those that are used in a ListView control. For example, GridView creates clean child ClientIDs, while ListView still has a naming container in the ClientID, presumably because of the template container on which you can’t set ClientIDMode. Predictable is useful, but only if all naming containers down the chain use this setting. Otherwise you’re right back to the munged ids that are pretty unpredictable. Another property, ClientIDRowSuffix, can be used in combination with ClientIDMode of Predictable to force a suffix onto list client controls. For example: <asp:GridView runat="server" ID="gvItems"              AutoGenerateColumns="false"             ClientIDMode="Static"              ClientIDRowSuffix="Id">     <Columns>     <asp:TemplateField>         <ItemTemplate>             <asp:Label runat="server" id="txtName"                        Text='<%# Eval("Name") %>'                   ClientIDMode="Predictable"/>         </ItemTemplate>     </asp:TemplateField>     <asp:TemplateField>         <ItemTemplate>         <asp:Label runat="server" id="txtId"                     Text='<%# Eval("Id") %>'                     ClientIDMode="Predictable" />         </ItemTemplate>     </asp:TemplateField>     </Columns>  </asp:GridView> generates client Ids inside of a column in the master page described earlier: <td>     <span id="txtName_0">Rick</span> </td> where the value after the underscore is the ClientIDRowSuffix field - in this case “Id” of the item data bound to the control. Note that all of the child controls require ClientIDMode=”Predictable” in order for the ClientIDRowSuffix to be applied, and the parent GridView controls need to be set to Static either explicitly or via Naming Container inheritance to give these simple names. It’s a bummer that ClientIDRowSuffix doesn’t work with Static to produce this automatically. Another real problem is that other controls process the ClientIDMode differently. For example, a ListView control processes the Predictable ClientIDMode differently and produces the following with the Static ListView and Predictable child controls: <span id="ctrl0_txtName_0">Rick</span> I couldn’t even figure out a way using ClientIDMode to get a simple ID that also uses a suffix short of falling back to manually generated ids using <%= %> expressions instead. Given the inconsistencies inside of list controls using <%= %>, ids for the ListView might not be a bad idea anyway. Inherit The final setting is Inherit, which is the default for all controls except Page. This means that controls by default inherit the parent naming container’s ClientIDMode setting. For more detailed information on ClientID behavior and different scenarios you can check out a blog post of mine on this subject: http://www.west-wind.com/weblog/posts/54760.aspx. ClientID Enhancements Summary The ClientIDMode property is a welcome addition to ASP.NET 4.0. To me this is probably the most useful WebForms feature as it allows me to generate clean IDs simply by setting ClientIDMode="Static" on either the page or inside of Web.config (in the Pages section) which applies the setting down to the entire page which is my 95% scenario. For the few cases when it matters - for list controls and inside of multi-use user controls or custom server controls) - I can use Predictable or even AutoID to force controls to unique names. For application-level page development, this is easy to accomplish and provides maximum usability for working with client script code against page controls. ViewStateMode Another area of large criticism for WebForms is ViewState. ViewState is used internally by ASP.NET to persist page-level changes to non-postback properties on controls as pages post back to the server. It’s a useful mechanism that works great for the overall mechanics of WebForms, but it can also cause all sorts of overhead for page operation as ViewState can very quickly get out of control and consume huge amounts of bandwidth in your page content. ViewState can also wreak havoc with client-side scripting applications that modify control properties that are tracked by ViewState, which can produce very unpredictable results on a Postback after client-side updates. Over the years in my own development, I’ve often turned off ViewState on pages to reduce overhead. Yes, you lose some functionality, but you can easily implement most of the common functionality in non-ViewState workarounds. Relying less on heavy ViewState controls and sticking with simpler controls or raw HTML constructs avoids getting around ViewState problems. In ASP.NET 3.x and prior, it wasn’t easy to control ViewState - you could turn it on or off and if you turned it off at the page or web.config level, you couldn’t turn it back on for specific controls. In short, it was an all or nothing approach. With ASP.NET 4.0, the new ViewStateMode property gives you more control. It allows you to disable ViewState globally either on the page or web.config level and then turn it back on for specific controls that might need it. ViewStateMode only works when EnableViewState="true" on the page or web.config level (which is the default). You can then use ViewStateMode of Disabled, Enabled or Inherit to control the ViewState settings on the page. If you’re shooting for minimal ViewState usage, the ideal situation is to set ViewStateMode to disabled on the Page or web.config level and only turn it back on particular controls: <%@Page Language="C#"      CodeBehind="WebForm2.aspx.cs"     Inherits="Westwind.WebStore.WebForm2"        ClientIDMode="Static"                ViewStateMode="Disabled"     EnableViewState="true"  %> <!-- this control has viewstate  --> <asp:TextBox runat="server" ID="txtName"  ViewStateMode="Enabled" />       <!-- this control has no viewstate - it inherits  from parent container --> <asp:TextBox runat="server" ID="txtAddress" /> Note that the EnableViewState="true" at the Page level isn’t required since it’s the default, but it’s important that the value is true. ViewStateMode has no effect if EnableViewState="false" at the page level. The main benefit of ViewStateMode is that it allows you to more easily turn off ViewState for most of the page and enable only a few key controls that might need it. For me personally, this is a perfect combination as most of my WebForm apps can get away without any ViewState at all. But some controls - especially third party controls - often don’t work well without ViewState enabled, and now it’s much easier to selectively enable controls rather than the old way, which required you to pretty much turn off ViewState for all controls that you didn’t want ViewState on. Inline HTML Encoding HTML encoding is an important feature to prevent cross-site scripting attacks in data entered by users on your site. In order to make it easier to create HTML encoded content, ASP.NET 4.0 introduces a new Expression syntax using <%: %> to encode string values. The encoding expression syntax looks like this: <%: "<script type='text/javascript'>" +     "alert('Really?');</script>" %> which produces properly encoded HTML: &lt;script type=&#39;text/javascript&#39; &gt;alert(&#39;Really?&#39;);&lt;/script&gt; Effectively this is a shortcut to: <%= HttpUtility.HtmlEncode( "<script type='text/javascript'>" + "alert('Really?');</script>") %> Of course the <%: %> syntax can also evaluate expressions just like <%= %> so the more common scenario applies this expression syntax against data your application is displaying. Here’s an example displaying some data model values: <%: Model.Address.Street %> This snippet shows displaying data from your application’s data store or more importantly, from data entered by users. Anything that makes it easier and less verbose to HtmlEncode text is a welcome addition to avoid potential cross-site scripting attacks. Although I listed Inline HTML Encoding here under WebForms, anything that uses the WebForms rendering engine including ASP.NET MVC, benefits from this feature. ScriptManager Enhancements The ASP.NET ScriptManager control in the past has introduced some nice ways to take programmatic and markup control over script loading, but there were a number of shortcomings in this control. The ASP.NET 4.0 ScriptManager has a number of improvements that make it easier to control script loading and addresses a few of the shortcomings that have often kept me from using the control in favor of manual script loading. The first is the AjaxFrameworkMode property which finally lets you suppress loading the ASP.NET AJAX runtime. Disabled doesn’t load any ASP.NET AJAX libraries, but there’s also an Explicit mode that lets you pick and choose the library pieces individually and reduce the footprint of ASP.NET AJAX script included if you are using the library. There’s also a new EnableCdn property that forces any script that has a new WebResource attribute CdnPath property set to a CDN supplied URL. If the script has this Attribute property set to a non-null/empty value and EnableCdn is enabled on the ScriptManager, that script will be served from the specified CdnPath. [assembly: WebResource(    "Westwind.Web.Resources.ww.jquery.js",    "application/x-javascript",    CdnPath =  "http://mysite.com/scripts/ww.jquery.min.js")] Cool, but a little too static for my taste since this value can’t be changed at runtime to point at a debug script as needed, for example. Assembly names for loading scripts from resources can now be simple names rather than fully qualified assembly names, which make it less verbose to reference scripts from assemblies loaded from your bin folder or the assembly reference area in web.config: <asp:ScriptManager runat="server" id="Id"          EnableCdn="true"         AjaxFrameworkMode="disabled">     <Scripts>         <asp:ScriptReference          Name="Westwind.Web.Resources.ww.jquery.js"         Assembly="Westwind.Web" />     </Scripts>        </asp:ScriptManager> The ScriptManager in 4.0 also supports script combining via the CompositeScript tag, which allows you to very easily combine scripts into a single script resource served via ASP.NET. Even nicer: You can specify the URL that the combined script is served with. Check out the following script manager markup that combines several static file scripts and a script resource into a single ASP.NET served resource from a static URL (allscripts.js): <asp:ScriptManager runat="server" id="Id"          EnableCdn="true"         AjaxFrameworkMode="disabled">     <CompositeScript          Path="~/scripts/allscripts.js">         <Scripts>             <asp:ScriptReference                    Path="~/scripts/jquery.js" />             <asp:ScriptReference                    Path="~/scripts/ww.jquery.js" />             <asp:ScriptReference            Name="Westwind.Web.Resources.editors.js"                 Assembly="Westwind.Web" />         </Scripts>     </CompositeScript> </asp:ScriptManager> When you render this into HTML, you’ll see a single script reference in the page: <script src="scripts/allscripts.debug.js"          type="text/javascript"></script> All you need to do to make this work is ensure that allscripts.js and allscripts.debug.js exist in the scripts folder of your application - they can be empty but the file has to be there. This is pretty cool, but you want to be real careful that you use unique URLs for each combination of scripts you combine or else browser and server caching will easily screw you up royally. The script manager also allows you to override native ASP.NET AJAX scripts now as any script references defined in the Scripts section of the ScriptManager trump internal references. So if you want custom behavior or you want to fix a possible bug in the core libraries that normally are loaded from resources, you can now do this simply by referencing the script resource name in the Name property and pointing at System.Web for the assembly. Not a common scenario, but when you need it, it can come in real handy. Still, there are a number of shortcomings in this control. For one, the ScriptManager and ClientScript APIs still have no common entry point so control developers are still faced with having to check and support both APIs to load scripts so that controls can work on pages that do or don’t have a ScriptManager on the page. The CdnUrl is static and compiled in, which is very restrictive. And finally, there’s still no control over where scripts get loaded on the page - ScriptManager still injects scripts into the middle of the HTML markup rather than in the header or optionally the footer. This, in turn, means there is little control over script loading order, which can be problematic for control developers. MetaDescription, MetaKeywords Page Properties There are also a number of additional Page properties that correspond to some of the other features discussed in this column: ClientIDMode, ClientTarget and ViewStateMode. Another minor but useful feature is that you can now directly access the MetaDescription and MetaKeywords properties on the Page object to set the corresponding meta tags programmatically. Updating these values programmatically previously required either <%= %> expressions in the page markup or dynamic insertion of literal controls into the page. You can now just set these properties programmatically on the Page object in any Control derived class on the page or the Page itself: Page.MetaKeywords = "ASP.NET,4.0,New Features"; Page.MetaDescription = "This article discusses the new features in ASP.NET 4.0"; Note, that there’s no corresponding ASP.NET tag for the HTML Meta element, so the only way to specify these values in markup and access them is via the @Page tag: <%@Page Language="C#"      CodeBehind="WebForm2.aspx.cs"     Inherits="Westwind.WebStore.WebForm2"      ClientIDMode="Static"                MetaDescription="Article that discusses what's                      new in ASP.NET 4.0"     MetaKeywords="ASP.NET,4.0,New Features" %> Nothing earth shattering but quite convenient. Visual Studio 2010 Enhancements for Web Development For Web development there are also a host of editor enhancements in Visual Studio 2010. Some of these are not Web specific but they are useful for Web developers in general. Text Editors Throughout Visual Studio 2010, the text editors have all been updated to a new core engine based on WPF which provides some interesting new features for various code editors including the nice ability to zoom in and out with Ctrl-MouseWheel to quickly change the size of text. There are many more API options to control the editor and although Visual Studio 2010 doesn’t yet use many of these features, we can look forward to enhancements in add-ins and future editor updates from the various language teams that take advantage of the visual richness that WPF provides to editing. On the negative side, I’ve noticed that occasionally the code editor and especially the HTML and JavaScript editors will lose the ability to use various navigation keys like arrows, back and delete keys, which requires closing and reopening the documents at times. This issue seems to be well documented so I suspect this will be addressed soon with a hotfix or within the first service pack. Overall though, the code editors work very well, especially given that they were re-written completely using WPF, which was one of my big worries when I first heard about the complete redesign of the editors. Multi-Targeting Visual Studio now targets all versions of the .NET framework from 2.0 forward. You can use Visual Studio 2010 to work on your ASP.NET 2, 3.0 and 3.5 applications which is a nice way to get your feet wet with the new development environment without having to make changes to existing applications. It’s nice to have one tool to work in for all the different versions. Multi-Monitor Support One cool feature of Visual Studio 2010 is the ability to drag windows out of the Visual Studio environment and out onto the desktop including onto another monitor easily. Since Web development often involves working with a host of designers at the same time - visual designer, HTML markup window, code behind and JavaScript editor - it’s really nice to be able to have a little more screen real estate to work on each of these editors. Microsoft made a welcome change in the environment. IntelliSense Snippets for HTML and JavaScript Editors The HTML and JavaScript editors now finally support IntelliSense scripts to create macro-based template expansions that have been in the core C# and Visual Basic code editors since Visual Studio 2005. Snippets allow you to create short XML-based template definitions that can act as static macros or real templates that can have replaceable values that can be embedded into the expanded text. The XML syntax for these snippets is straight forward and it’s pretty easy to create custom snippets manually. You can easily create snippets using XML and store them in your custom snippets folder (C:\Users\rstrahl\Documents\Visual Studio 2010\Code Snippets\Visual Web Developer\My HTML Snippets and My JScript Snippets), but it helps to use one of the third-party tools that exist to simplify the process for you. I use SnippetEditor, by Bill McCarthy, which makes short work of creating snippets interactively (http://snippeteditor.codeplex.com/). Note: You may have to manually add the Visual Studio 2010 User specific Snippet folders to this tool to see existing ones you’ve created. Code snippets are some of the biggest time savers and HTML editing more than anything deals with lots of repetitive tasks that lend themselves to text expansion. Visual Studio 2010 includes a slew of built-in snippets (that you can also customize!) and you can create your own very easily. If you haven’t done so already, I encourage you to spend a little time examining your coding patterns and find the repetitive code that you write and convert it into snippets. I’ve been using CodeRush for this for years, but now you can do much of the basic expansion natively for HTML and JavaScript snippets. jQuery Integration Is Now Native jQuery is a popular JavaScript library and recently Microsoft has recently stated that it will become the primary client-side scripting technology to drive higher level script functionality in various ASP.NET Web projects that Microsoft provides. In Visual Studio 2010, the default full project template includes jQuery as part of a new project including the support files that provide IntelliSense (-vsdoc files). IntelliSense support for jQuery is now also baked into Visual Studio 2010, so unlike Visual Studio 2008 which required a separate download, no further installs are required for a rich IntelliSense experience with jQuery. Summary ASP.NET 4.0 brings many useful improvements to the platform, but thankfully most of the changes are incremental changes that don’t compromise backwards compatibility and they allow developers to ease into the new features one feature at a time. None of the changes in ASP.NET 4.0 or Visual Studio 2010 are monumental or game changers. The bigger features are language and .NET Framework changes that are also optional. This ASP.NET and tools release feels more like fine tuning and getting some long-standing kinks worked out of the platform. It shows that the ASP.NET team is dedicated to paying attention to community feedback and responding with changes to the platform and development environment based on this feedback. If you haven’t gotten your feet wet with ASP.NET 4.0 and Visual Studio 2010, there’s no reason not to give it a shot now - the ASP.NET 4.0 platform is solid and Visual Studio 2010 works very well for a brand new release. Check it out. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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  • Using HTML 5 SessionState to save rendered Page Content

    - by Rick Strahl
    HTML 5 SessionState and LocalStorage are very useful and super easy to use to manage client side state. For building rich client side or SPA style applications it's a vital feature to be able to cache user data as well as HTML content in order to swap pages in and out of the browser's DOM. What might not be so obvious is that you can also use the sessionState and localStorage objects even in classic server rendered HTML applications to provide caching features between pages. These APIs have been around for a long time and are supported by most relatively modern browsers and even all the way back to IE8, so you can use them safely in your Web applications. SessionState and LocalStorage are easy The APIs that make up sessionState and localStorage are very simple. Both object feature the same API interface which  is a simple, string based key value store that has getItem, setItem, removeitem, clear and  key methods. The objects are also pseudo array objects and so can be iterated like an array with  a length property and you have array indexers to set and get values with. Basic usage  for storing and retrieval looks like this (using sessionStorage, but the syntax is the same for localStorage - just switch the objects):// set var lastAccess = new Date().getTime(); if (sessionStorage) sessionStorage.setItem("myapp_time", lastAccess.toString()); // retrieve in another page or on a refresh var time = null; if (sessionStorage) time = sessionStorage.getItem("myapp_time"); if (time) time = new Date(time * 1); else time = new Date(); sessionState stores data that is browser session specific and that has a liftetime of the active browser session or window. Shut down the browser or tab and the storage goes away. localStorage uses the same API interface, but the lifetime of the data is permanently stored in the browsers storage area until deleted via code or by clearing out browser cookies (not the cache). Both sessionStorage and localStorage space is limited. The spec is ambiguous about this - supposedly sessionStorage should allow for unlimited size, but it appears that most WebKit browsers support only 2.5mb for either object. This means you have to be careful what you store especially since other applications might be running on the same domain and also use the storage mechanisms. That said 2.5mb worth of character data is quite a bit and would go a long way. The easiest way to get a feel for how sessionState and localStorage work is to look at a simple example. You can go check out the following example online in Plunker: http://plnkr.co/edit/0ICotzkoPjHaWa70GlRZ?p=preview which looks like this: Plunker is an online HTML/JavaScript editor that lets you write and run Javascript code and similar to JsFiddle, but a bit cleaner to work in IMHO (thanks to John Papa for turning me on to it). The sample has two text boxes with counts that update session/local storage every time you click the related button. The counts are 'cached' in Session and Local storage. The point of these examples is that both counters survive full page reloads, and the LocalStorage counter survives a complete browser shutdown and restart. Go ahead and try it out by clicking the Reload button after updating both counters and then shutting down the browser completely and going back to the same URL (with the same browser). What you should see is that reloads leave both counters intact at the counted values, while a browser restart will leave only the local storage counter intact. The code to deal with the SessionStorage (and LocalStorage not shown here) in the example is isolated into a couple of wrapper methods to simplify the code: function getSessionCount() { var count = 0; if (sessionStorage) { var count = sessionStorage.getItem("ss_count"); count = !count ? 0 : count * 1; } $("#txtSession").val(count); return count; } function setSessionCount(count) { if (sessionStorage) sessionStorage.setItem("ss_count", count.toString()); } These two functions essentially load and store a session counter value. The two key methods used here are: sessionStorage.getItem(key); sessionStorage.setItem(key,stringVal); Note that the value given to setItem and return by getItem has to be a string. If you pass another type you get an error. Don't let that limit you though - you can easily enough store JSON data in a variable so it's quite possible to pass complex objects and store them into a single sessionStorage value:var user = { name: "Rick", id="ricks", level=8 } sessionStorage.setItem("app_user",JSON.stringify(user)); to retrieve it:var user = sessionStorage.getItem("app_user"); if (user) user = JSON.parse(user); Simple! If you're using the Chrome Developer Tools (F12) you can also check out the session and local storage state on the Resource tab:   You can also use this tool to refresh or remove entries from storage. What we just looked at is a purely client side implementation where a couple of counters are stored. For rich client centric AJAX applications sessionStorage and localStorage provide a very nice and simple API to store application state while the application is running. But you can also use these storage mechanisms to manage server centric HTML applications when you combine server rendering with some JavaScript to perform client side data caching. You can both store some state information and data on the client (ie. store a JSON object and carry it forth between server rendered HTML requests) or you can use it for good old HTTP based caching where some rendered HTML is saved and then restored later. Let's look at the latter with a real life example. Why do I need Client-side Page Caching for Server Rendered HTML? I don't know about you, but in a lot of my existing server driven applications I have lists that display a fair amount of data. Typically these lists contain links to then drill down into more specific data either for viewing or editing. You can then click on a link and go off to a detail page that provides more concise content. So far so good. But now you're done with the detail page and need to get back to the list, so you click on a 'bread crumbs trail' or an application level 'back to list' button and… …you end up back at the top of the list - the scroll position, the current selection in some cases even filters conditions - all gone with the wind. You've left behind the state of the list and are starting from scratch in your browsing of the list from the top. Not cool! Sound familiar? This a pretty common scenario with server rendered HTML content where it's so common to display lists to drill into, only to lose state in the process of returning back to the original list. Look at just about any traditional forums application, or even StackOverFlow to see what I mean here. Scroll down a bit to look at a post or entry, drill in then use the bread crumbs or tab to go back… In some cases returning to the top of a list is not a big deal. On StackOverFlow that sort of works because content is turning around so quickly you probably want to actually look at the top posts. Not always though - if you're browsing through a list of search topics you're interested in and drill in there's no way back to that position. Essentially anytime you're actively browsing the items in the list, that's when state becomes important and if it's not handled the user experience can be really disrupting. Content Caching If you're building client centric SPA style applications this is a fairly easy to solve problem - you tend to render the list once and then update the page content to overlay the detail content, only hiding the list temporarily until it's used again later. It's relatively easy to accomplish this simply by hiding content on the page and later making it visible again. But if you use server rendered content, hanging on to all the detail like filters, selections and scroll position is not quite as easy. Or is it??? This is where sessionStorage comes in handy. What if we just save the rendered content of a previous page, and then restore it when we return to this page based on a special flag that tells us to use the cached version? Let's see how we can do this. A real World Use Case Recently my local ISP asked me to help out with updating an ancient classifieds application. They had a very busy, local classifieds app that was originally an ASP classic application. The old app was - wait for it: frames based - and even though I lobbied against it, the decision was made to keep the frames based layout to allow rapid browsing of the hundreds of posts that are made on a daily basis. The primary reason they wanted this was precisely for the ability to quickly browse content item by item. While I personally hate working with Frames, I have to admit that the UI actually works well with the frames layout as long as you're running on a large desktop screen. You can check out the frames based desktop site here: http://classifieds.gorge.net/ However when I rebuilt the app I also added a secondary view that doesn't use frames. The main reason for this of course was for mobile displays which work horribly with frames. So there's a somewhat mobile friendly interface to the interface, which ditches the frames and uses some responsive design tweaking for mobile capable operation: http://classifeds.gorge.net/mobile  (or browse the base url with your browser width under 800px)   Here's what the mobile, non-frames view looks like:   As you can see this means that the list of classifieds posts now is a list and there's a separate page for drilling down into the item. And of course… originally we ran into that usability issue I mentioned earlier where the browse, view detail, go back to the list cycle resulted in lost list state. Originally in mobile mode you scrolled through the list, found an item to look at and drilled in to display the item detail. Then you clicked back to the list and BAM - you've lost your place. Because there are so many items added on a daily basis the full list is never fully loaded, but rather there's a "Load Additional Listings"  entry at the button. Not only did we originally lose our place when coming back to the list, but any 'additionally loaded' items are no longer there because the list was now rendering  as if it was the first page hit. The additional listings, and any filters, the selection of an item all were lost. Major Suckage! Using Client SessionStorage to cache Server Rendered Content To work around this problem I decided to cache the rendered page content from the list in SessionStorage. Anytime the list renders or is updated with Load Additional Listings, the page HTML is cached and stored in Session Storage. Any back links from the detail page or the login or write entry forms then point back to the list page with a back=true query string parameter. If the server side sees this parameter it doesn't render the part of the page that is cached. Instead the client side code retrieves the data from the sessionState cache and simply inserts it into the page. It sounds pretty simple, and the overall the process is really easy, but there are a few gotchas that I'll discuss in a minute. But first let's look at the implementation. Let's start with the server side here because that'll give a quick idea of the doc structure. As I mentioned the server renders data from an ASP.NET MVC view. On the list page when returning to the list page from the display page (or a host of other pages) looks like this: https://classifieds.gorge.net/list?back=True The query string value is a flag, that indicates whether the server should render the HTML. Here's what the top level MVC Razor view for the list page looks like:@model MessageListViewModel @{ ViewBag.Title = "Classified Listing"; bool isBack = !string.IsNullOrEmpty(Request.QueryString["back"]); } <form method="post" action="@Url.Action("list")"> <div id="SizingContainer"> @if (!isBack) { @Html.Partial("List_CommandBar_Partial", Model) <div id="PostItemContainer" class="scrollbox" xstyle="-webkit-overflow-scrolling: touch;"> @Html.Partial("List_Items_Partial", Model) @if (Model.RequireLoadEntry) { <div class="postitem loadpostitems" style="padding: 15px;"> <div id="LoadProgress" class="smallprogressright"></div> <div class="control-progress"> Load additional listings... </div> </div> } </div> } </div> </form> As you can see the query string triggers a conditional block that if set is simply not rendered. The content inside of #SizingContainer basically holds  the entire page's HTML sans the headers and scripts, but including the filter options and menu at the top. In this case this makes good sense - in other situations the fact that the menu or filter options might be dynamically updated might make you only cache the list rather than essentially the entire page. In this particular instance all of the content works and produces the proper result as both the list along with any filter conditions in the form inputs are restored. Ok, let's move on to the client. On the client there are two page level functions that deal with saving and restoring state. Like the counter example I showed earlier, I like to wrap the logic to save and restore values from sessionState into a separate function because they are almost always used in several places.page.saveData = function(id) { if (!sessionStorage) return; var data = { id: id, scroll: $("#PostItemContainer").scrollTop(), html: $("#SizingContainer").html() }; sessionStorage.setItem("list_html",JSON.stringify(data)); }; page.restoreData = function() { if (!sessionStorage) return; var data = sessionStorage.getItem("list_html"); if (!data) return null; return JSON.parse(data); }; The data that is saved is an object which contains an ID which is the selected element when the user clicks and a scroll position. These two values are used to reset the scroll position when the data is used from the cache. Finally the html from the #SizingContainer element is stored, which makes for the bulk of the document's HTML. In this application the HTML captured could be a substantial bit of data. If you recall, I mentioned that the server side code renders a small chunk of data initially and then gets more data if the user reads through the first 50 or so items. The rest of the items retrieved can be rather sizable. Other than the JSON deserialization that's Ok. Since I'm using SessionStorage the storage space has no immediate limits. Next is the core logic to handle saving and restoring the page state. At first though this would seem pretty simple, and in some cases it might be, but as the following code demonstrates there are a few gotchas to watch out for. Here's the relevant code I use to save and restore:$( function() { … var isBack = getUrlEncodedKey("back", location.href); if (isBack) { // remove the back key from URL setUrlEncodedKey("back", "", location.href); var data = page.restoreData(); // restore from sessionState if (!data) { // no data - force redisplay of the server side default list window.location = "list"; return; } $("#SizingContainer").html(data.html); var el = $(".postitem[data-id=" + data.id + "]"); $(".postitem").removeClass("highlight"); el.addClass("highlight"); $("#PostItemContainer").scrollTop(data.scroll); setTimeout(function() { el.removeClass("highlight"); }, 2500); } else if (window.noFrames) page.saveData(null); // save when page loads $("#SizingContainer").on("click", ".postitem", function() { var id = $(this).attr("data-id"); if (!id) return true; if (window.noFrames) page.saveData(id); var contentFrame = window.parent.frames["Content"]; if (contentFrame) contentFrame.location.href = "show/" + id; else window.location.href = "show/" + id; return false; }); … The code starts out by checking for the back query string flag which triggers restoring from the client cache. If cached the cached data structure is read from sessionStorage. It's important here to check if data was returned. If the user had back=true on the querystring but there is no cached data, he likely bookmarked this page or otherwise shut down the browser and came back to this URL. In that case the server didn't render any detail and we have no cached data, so all we can do is redirect to the original default list view using window.location. If we continued the page would render no data - so make sure to always check the cache retrieval result. Always! If there is data the it's loaded and the data.html data is restored back into the document by simply injecting the HTML back into the document's #SizingContainer element:$("#SizingContainer").html(data.html); It's that simple and it's quite quick even with a fully loaded list of additional items and on a phone. The actual HTML data is stored to the cache on every page load initially and then again when the user clicks on an element to navigate to a particular listing. The former ensures that the client cache always has something in it, and the latter updates with additional information for the selected element. For the click handling I use a data-id attribute on the list item (.postitem) in the list and retrieve the id from that. That id is then used to navigate to the actual entry as well as storing that Id value in the saved cached data. The id is used to reset the selection by searching for the data-id value in the restored elements. The overall process of this save/restore process is pretty straight forward and it doesn't require a bunch of code, yet it yields a huge improvement in the usability of the site on mobile devices (or anybody who uses the non-frames view). Some things to watch out for As easy as it conceptually seems to simply store and retrieve cached content, you have to be quite aware what type of content you are caching. The code above is all that's specific to cache/restore cycle and it works, but it took a few tweaks to the rest of the script code and server code to make it all work. There were a few gotchas that weren't immediately obvious. Here are a few things to pay attention to: Event Handling Logic Timing of manipulating DOM events Inline Script Code Bookmarking to the Cache Url when no cache exists Do you have inline script code in your HTML? That script code isn't going to run if you restore from cache and simply assign or it may not run at the time you think it would normally in the DOM rendering cycle. JavaScript Event Hookups The biggest issue I ran into with this approach almost immediately is that originally I had various static event handlers hooked up to various UI elements that are now cached. If you have an event handler like:$("#btnSearch").click( function() {…}); that works fine when the page loads with server rendered HTML, but that code breaks when you now load the HTML from cache. Why? Because the elements you're trying to hook those events to may not actually be there - yet. Luckily there's an easy workaround for this by using deferred events. With jQuery you can use the .on() event handler instead:$("#SelectionContainer").on("click","#btnSearch", function() {…}); which monitors a parent element for the events and checks for the inner selector elements to handle events on. This effectively defers to runtime event binding, so as more items are added to the document bindings still work. For any cached content use deferred events. Timing of manipulating DOM Elements Along the same lines make sure that your DOM manipulation code follows the code that loads the cached content into the page so that you don't manipulate DOM elements that don't exist just yet. Ideally you'll want to check for the condition to restore cached content towards the top of your script code, but that can be tricky if you have components or other logic that might not all run in a straight line. Inline Script Code Here's another small problem I ran into: I use a DateTime Picker widget I built a while back that relies on the jQuery date time picker. I also created a helper function that allows keyboard date navigation into it that uses JavaScript logic. Because MVC's limited 'object model' the only way to embed widget content into the page is through inline script. This code broken when I inserted the cached HTML into the page because the script code was not available when the component actually got injected into the page. As the last bullet - it's a matter of timing. There's no good work around for this - in my case I pulled out the jQuery date picker and relied on native <input type="date" /> logic instead - a better choice these days anyway, especially since this view is meant to be primarily to serve mobile devices which actually support date input through the browser (unlike desktop browsers of which only WebKit seems to support it). Bookmarking Cached Urls When you cache HTML content you have to make a decision whether you cache on the client and also not render that same content on the server. In the Classifieds app I didn't render server side content so if the user comes to the page with back=True and there is no cached content I have to a have a Plan B. Typically this happens when somebody ends up bookmarking the back URL. The easiest and safest solution for this scenario is to ALWAYS check the cache result to make sure it exists and if not have a safe URL to go back to - in this case to the plain uncached list URL which amounts to effectively redirecting. This seems really obvious in hindsight, but it's easy to overlook and not see a problem until much later, when it's not obvious at all why the page is not rendering anything. Don't use <body> to replace Content Since we're practically replacing all the HTML in the page it may seem tempting to simply replace the HTML content of the <body> tag. Don't. The body tag usually contains key things that should stay in the page and be there when it loads. Specifically script tags and elements and possibly other embedded content. It's best to create a top level DOM element specifically as a placeholder container for your cached content and wrap just around the actual content you want to replace. In the app above the #SizingContainer is that container. Other Approaches The approach I've used for this application is kind of specific to the existing server rendered application we're running and so it's just one approach you can take with caching. However for server rendered content caching this is a pattern I've used in a few apps to retrofit some client caching into list displays. In this application I took the path of least resistance to the existing server rendering logic. Here are a few other ways that come to mind: Using Partial HTML Rendering via AJAXInstead of rendering the page initially on the server, the page would load empty and the client would render the UI by retrieving the respective HTML and embedding it into the page from a Partial View. This effectively makes the initial rendering and the cached rendering logic identical and removes the server having to decide whether this request needs to be rendered or not (ie. not checking for a back=true switch). All the logic related to caching is made on the client in this case. Using JSON Data and Client RenderingThe hardcore client option is to do the whole UI SPA style and pull data from the server and then use client rendering or databinding to pull the data down and render using templates or client side databinding with knockout/angular et al. As with the Partial Rendering approach the advantage is that there's no difference in the logic between pulling the data from cache or rendering from scratch other than the initial check for the cache request. Of course if the app is a  full on SPA app, then caching may not be required even - the list could just stay in memory and be hidden and reactivated. I'm sure there are a number of other ways this can be handled as well especially using  AJAX. AJAX rendering might simplify the logic, but it also complicates search engine optimization since there's no content loaded initially. So there are always tradeoffs and it's important to look at all angles before deciding on any sort of caching solution in general. State of the Session SessionState and LocalStorage are easy to use in client code and can be integrated even with server centric applications to provide nice caching features of content and data. In this post I've shown a very specific scenario of storing HTML content for the purpose of remembering list view data and state and making the browsing experience for lists a bit more friendly, especially if there's dynamically loaded content involved. If you haven't played with sessionStorage or localStorage I encourage you to give it a try. There's a lot of cool stuff that you can do with this beyond the specific scenario I've covered here… Resources Overview of localStorage (also applies to sessionStorage) Web Storage Compatibility Modernizr Test Suite© Rick Strahl, West Wind Technologies, 2005-2013Posted in JavaScript  HTML5  ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Lot's of errors by insserv on apt-get operations after trying to install tomcat

    - by yankee
    I wanted to install tomcat on my Debian 6.0.4 machine. I tried apt-get install tomcat6-user which worked fine. But then I changed my mind about the user installation and wanted to install the package tomcat6. This resulted in a bunch of errors (see below). Now whatever I try to do with apt-get or with aptitude (trying to remove tomcat6-user, trying to remove tomcat6, trying to perform an apt-get upgrade,...) just results in the same list of errors. How did I manage that? And how can I fix it? # apt-get install tomcat6 Reading package lists... Done Building dependency tree Reading state information... Done The following extra packages will be installed: authbind Suggested packages: tomcat6-docs tomcat6-admin tomcat6-examples libtcnative-1 The following NEW packages will be installed: authbind tomcat6 0 upgraded, 2 newly installed, 0 to remove and 32 not upgraded. Need to get 56.6 kB of archives. After this operation, 442 kB of additional disk space will be used. Do you want to continue [Y/n]? Get:1 http://mirror.hetzner.de/debian/packages/ squeeze/main authbind amd64 1.2.0 [17.3 kB] Get:2 http://mirror.hetzner.de/debian/security/ squeeze/updates/main tomcat6 all 6.0.35-1+squeeze2 [39.3 kB] Fetched 56.6 kB in 0s (441 kB/s) Preconfiguring packages ... Selecting previously deselected package authbind. (Reading database ... 34717 files and directories currently installed.) Unpacking authbind (from .../authbind_1.2.0_amd64.deb) ... Selecting previously deselected package tomcat6. Unpacking tomcat6 (from .../tomcat6_6.0.35-1+squeeze2_all.deb) ... Processing triggers for man-db ... Setting up authbind (1.2.0) ... Setting up tomcat6 (6.0.35-1+squeeze2) ... Creating config file /etc/default/tomcat6 with new version Adding system user `tomcat6' (UID 108) ... Adding new user `tomcat6' (UID 108) with group `tomcat6' ... Not creating home directory `/usr/share/tomcat6'. insserv: warning: script 'S99iptables-custom' missing LSB tags and overrides insserv: warning: script 'iptables-custom' missing LSB tags and overrides insserv: There is a loop at service iptables-custom if started insserv: There is a loop between service rmnologin and mountnfs if started insserv: loop involving service mountnfs at depth 6 insserv: loop involving service networking at depth 5 insserv: loop involving service kbd at depth 9 insserv: There is a loop between service rmnologin and mountall-bootclean if started insserv: loop involving service mountall-bootclean at depth 5 insserv: loop involving service mountall at depth 4 insserv: There is a loop between service iptables-custom and lvm2 if started insserv: loop involving service lvm2 at depth 2 insserv: loop involving service udev at depth 1 insserv: There is a loop at service rmnologin if started insserv: There is a loop between service iptables-custom and checkroot if started insserv: loop involving service checkroot at depth 2 insserv: loop involving service keyboard-setup at depth 1 insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Max recursions depth 99 reached insserv: loop involving service courier-imap-ssl at depth 1 insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: loop involving service hwclockfirst at depth 2 insserv: loop involving service mountoverflowtmp at depth 9 insserv: loop involving service checkfs at depth 6 insserv: loop involving service mdadm-raid at depth 4 insserv: loop involving service hostname at depth 3 insserv: There is a loop between service iptables-custom and ifupdown-clean if started insserv: loop involving service ifupdown-clean at depth 5 insserv: There is a loop between service rmnologin and mountall if started insserv: There is a loop between service iptables-custom and mountdevsubfs if started insserv: loop involving service mountdevsubfs at depth 1 insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: loop involving service mtab at depth 6 insserv: There is a loop between service rmnologin and mountoverflowtmp if started insserv: Starting iptables-custom depends on rmnologin and therefore on system facility `$all' which can not be true! insserv: exiting now without changing boot order! update-rc.d: error: insserv rejected the script header dpkg: error processing tomcat6 (--configure): subprocess installed post-installation script returned error exit status 1 configured to not write apport reports Errors were encountered while processing: tomcat6 E: Sub-process /usr/bin/dpkg returned an error code (1)

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  • Java Cloud Service Integration to REST Service

    - by Jani Rautiainen
    Service (JCS) provides a platform to develop and deploy business applications in the cloud. In Fusion Applications Cloud deployments customers do not have the option to deploy custom applications developed with JDeveloper to ensure the integrity and supportability of the hosted application service. Instead the custom applications can be deployed to the JCS and integrated to the Fusion Application Cloud instance. This series of articles will go through the features of JCS, provide end-to-end examples on how to develop and deploy applications on JCS and how to integrate them with the Fusion Applications instance. In this article a custom application integrating with REST service will be implemented. We will use REST services provided by Taleo as an example; however the same approach will work with any REST service. In this example the data from the REST service is used to populate a dynamic table. Pre-requisites Access to Cloud instance In order to deploy the application access to a JCS instance is needed, a free trial JCS instance can be obtained from Oracle Cloud site. To register you will need a credit card even if the credit card will not be charged. To register simply click "Try it" and choose the "Java" option. The confirmation email will contain the connection details. See this video for example of the registration.Once the request is processed you will be assigned 2 service instances; Java and Database. Applications deployed to the JCS must use Oracle Database Cloud Service as their underlying database. So when JCS instance is created a database instance is associated with it using a JDBC data source.The cloud services can be monitored and managed through the web UI. For details refer to Getting Started with Oracle Cloud. JDeveloper JDeveloper contains Cloud specific features related to e.g. connection and deployment. To use these features download the JDeveloper from JDeveloper download site by clicking the "Download JDeveloper 11.1.1.7.1 for ADF deployment on Oracle Cloud" link, this version of JDeveloper will have the JCS integration features that will be used in this article. For versions that do not include the Cloud integration features the Oracle Java Cloud Service SDK or the JCS Java Console can be used for deployment. For details on installing and configuring the JDeveloper refer to the installation guideFor details on SDK refer to Using the Command-Line Interface to Monitor Oracle Java Cloud Service and Using the Command-Line Interface to Manage Oracle Java Cloud Service. Access to a local database The database associated with the JCS instance cannot be connected to with JDBC.  Since creating ADFbc business component requires a JDBC connection we will need access to a local database. 3rd party libraries This example will use some 3rd party libraries for implementing the REST service call and processing the input / output content. Other libraries may also be used, however these are tested to work. Jersey 1.x Jersey library will be used as a client to make the call to the REST service. JCS documentation for supported specifications states: Java API for RESTful Web Services (JAX-RS) 1.1 So Jersey 1.x will be used. Download the single-JAR Jersey bundle; in this example Jersey 1.18 JAR bundle is used. Json-simple Jjson-simple library will be used to process the json objects. Download the  JAR file; in this example json-simple-1.1.1.jar is used. Accessing data in Taleo Before implementing the application it is beneficial to familiarize oneself with the data in Taleo. Easiest way to do this is by using a RESTClient on your browser. Once added to the browser you can access the UI: The client can be used to call the REST services to test the URLs and data before adding them into the application. First derive the base URL for the service this can be done with: Method: GET URL: https://tbe.taleo.net/MANAGER/dispatcher/api/v1/serviceUrl/<company name> The response will contain the base URL to be used for the service calls for the company. Next obtain authentication token with: Method: POST URL: https://ch.tbe.taleo.net/CH07/ats/api/v1/login?orgCode=<company>&userName=<user name>&password=<password> The response includes an authentication token that can be used for few hours to authenticate with the service: {   "response": {     "authToken": "webapi26419680747505890557"   },   "status": {     "detail": {},     "success": true   } } To authenticate the service calls navigate to "Headers -> Custom Header": And add a new request header with: Name: Cookie Value: authToken=webapi26419680747505890557 Once authentication token is defined the tool can be used to invoke REST services; for example: Method: GET URL: https://ch.tbe.taleo.net/CH07/ats/api/v1/object/candidate/search.xml?status=16 This data will be used on the application to be created. For details on the Taleo REST services refer to the Taleo Business Edition REST API Guide. Create Application First Fusion Web Application is created and configured. Start JDeveloper and click "New Application": Application Name: JcsRestDemo Application Package Prefix: oracle.apps.jcs.test Application Template: Fusion Web Application (ADF) Configure Local Cloud Connection Follow the steps documented in the "Java Cloud Service ADF Web Application" article to configure a local database connection needed to create the ADFbc objects. Configure Libraries Add the 3rd party libraries into the class path. Create the following directory and copy the jar files into it: <JDEV_USER_HOME>/JcsRestDemo/lib  Select the "Model" project, navigate "Application -> Project Properties -> Libraries and Classpath -> Add JAR / Directory" and add the 2 3rd party libraries: Accessing Data from Taleo To access data from Taleo using the REST service the 3rd party libraries will be used. 2 Java classes are implemented, one representing the Candidate object and another for accessing the Taleo repository Candidate Candidate object is a POJO object used to represent the candidate data obtained from the Taleo repository. The data obtained will be used to populate the ADFbc object used to display the data on the UI. The candidate object contains simply the variables we obtain using the REST services and the getters / setters for them: Navigate "New -> General -> Java -> Java Class", enter "Candidate" as the name and create it in the package "oracle.apps.jcs.test.model".  Copy / paste the following as the content: import oracle.jbo.domain.Number; public class Candidate { private Number candId; private String firstName; private String lastName; public Candidate() { super(); } public Candidate(Number candId, String firstName, String lastName) { super(); this.candId = candId; this.firstName = firstName; this.lastName = lastName; } public void setCandId(Number candId) { this.candId = candId; } public Number getCandId() { return candId; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getFirstName() { return firstName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getLastName() { return lastName; } } Taleo Repository Taleo repository class will interact with the Taleo REST services. The logic will query data from Taleo and populate Candidate objects with the data. The Candidate object will then be used to populate the ADFbc object used to display data on the UI. Navigate "New -> General -> Java -> Java Class", enter "TaleoRepository" as the name and create it in the package "oracle.apps.jcs.test.model".  Copy / paste the following as the content (for details of the implementation refer to the documentation in the code): import com.sun.jersey.api.client.Client; import com.sun.jersey.api.client.ClientResponse; import com.sun.jersey.api.client.WebResource; import com.sun.jersey.core.util.MultivaluedMapImpl; import java.io.StringReader; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import java.util.Map; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.MultivaluedMap; import oracle.jbo.domain.Number; import org.json.simple.JSONArray; import org.json.simple.JSONObject; import org.json.simple.parser.JSONParser; /** * This class interacts with the Taleo REST services */ public class TaleoRepository { /** * Connection information needed to access the Taleo services */ String _company = null; String _userName = null; String _password = null; /** * Jersey client used to access the REST services */ Client _client = null; /** * Parser for processing the JSON objects used as * input / output for the services */ JSONParser _parser = null; /** * The base url for constructing the REST URLs. This is obtained * from Taleo with a service call */ String _baseUrl = null; /** * Authentication token obtained from Taleo using a service call. * The token can be used to authenticate on subsequent * service calls. The token will expire in 4 hours */ String _authToken = null; /** * Static url that can be used to obtain the url used to construct * service calls for a given company */ private static String _taleoUrl = "https://tbe.taleo.net/MANAGER/dispatcher/api/v1/serviceUrl/"; /** * Default constructor for the repository * Authentication details are passed as parameters and used to generate * authentication token. Note that each service call will * generate its own token. This is done to avoid dealing with the expiry * of the token. Also only 20 tokens are allowed per user simultaneously. * So instead for each call there is login / logout. * * @param company the company for which the service calls are made * @param userName the user name to authenticate with * @param password the password to authenticate with. */ public TaleoRepository(String company, String userName, String password) { super(); _company = company; _userName = userName; _password = password; _client = Client.create(); _parser = new JSONParser(); _baseUrl = getBaseUrl(); } /** * This obtains the base url for a company to be used * to construct the urls for service calls * @return base url for the service calls */ private String getBaseUrl() { String result = null; if (null != _baseUrl) { result = _baseUrl; } else { try { String company = _company; WebResource resource = _client.resource(_taleoUrl + company); ClientResponse response = resource.type(MediaType.APPLICATION_FORM_URLENCODED_TYPE).get(ClientResponse.class); String entity = response.getEntity(String.class); JSONObject jsonObject = (JSONObject)_parser.parse(new StringReader(entity)); JSONObject jsonResponse = (JSONObject)jsonObject.get("response"); result = (String)jsonResponse.get("URL"); } catch (Exception ex) { ex.printStackTrace(); } } return result; } /** * Generates authentication token, that can be used to authenticate on * subsequent service calls. Note that each service call will * generate its own token. This is done to avoid dealing with the expiry * of the token. Also only 20 tokens are allowed per user simultaneously. * So instead for each call there is login / logout. * @return authentication token that can be used to authenticate on * subsequent service calls */ private String login() { String result = null; try { MultivaluedMap<String, String> formData = new MultivaluedMapImpl(); formData.add("orgCode", _company); formData.add("userName", _userName); formData.add("password", _password); WebResource resource = _client.resource(_baseUrl + "login"); ClientResponse response = resource.type(MediaType.APPLICATION_FORM_URLENCODED_TYPE).post(ClientResponse.class, formData); String entity = response.getEntity(String.class); JSONObject jsonObject = (JSONObject)_parser.parse(new StringReader(entity)); JSONObject jsonResponse = (JSONObject)jsonObject.get("response"); result = (String)jsonResponse.get("authToken"); } catch (Exception ex) { throw new RuntimeException("Unable to login ", ex); } if (null == result) throw new RuntimeException("Unable to login "); return result; } /** * Releases a authentication token. Each call to login must be followed * by call to logout after the processing is done. This is required as * the tokens are limited to 20 per user and if not released the tokens * will only expire after 4 hours. * @param authToken */ private void logout(String authToken) { WebResource resource = _client.resource(_baseUrl + "logout"); resource.header("cookie", "authToken=" + authToken).post(ClientResponse.class); } /** * This method is used to obtain a list of candidates using a REST * service call. At this example the query is hard coded to query * based on status. The url constructed to access the service is: * <_baseUrl>/object/candidate/search.xml?status=16 * @return List of candidates obtained with the service call */ public List<Candidate> getCandidates() { List<Candidate> result = new ArrayList<Candidate>(); try { // First login, note that in finally block we must have logout _authToken = "authToken=" + login(); /** * Construct the URL, the resulting url will be: * <_baseUrl>/object/candidate/search.xml?status=16 */ MultivaluedMap<String, String> formData = new MultivaluedMapImpl(); formData.add("status", "16"); JSONArray searchResults = (JSONArray)getTaleoResource("object/candidate/search", "searchResults", formData); /** * Process the results, the resulting JSON object is something like * this (simplified for readability): * * { * "response": * { * "searchResults": * [ * { * "candidate": * { * "candId": 211, * "firstName": "Mary", * "lastName": "Stochi", * logic here will find the candidate object(s), obtain the desired * data from them, construct a Candidate object based on the data * and add it to the results. */ for (Object object : searchResults) { JSONObject temp = (JSONObject)object; JSONObject candidate = (JSONObject)findObject(temp, "candidate"); Long candIdTemp = (Long)candidate.get("candId"); Number candId = (null == candIdTemp ? null : new Number(candIdTemp)); String firstName = (String)candidate.get("firstName"); String lastName = (String)candidate.get("lastName"); result.add(new Candidate(candId, firstName, lastName)); } } catch (Exception ex) { ex.printStackTrace(); } finally { if (null != _authToken) logout(_authToken); } return result; } /** * Convenience method to construct url for the service call, invoke the * service and obtain a resource from the response * @param path the path for the service to be invoked. This is combined * with the base url to construct a url for the service * @param resource the key for the object in the response that will be * obtained * @param parameters any parameters used for the service call. The call * is slightly different depending whether parameters exist or not. * @return the resource from the response for the service call */ private Object getTaleoResource(String path, String resource, MultivaluedMap<String, String> parameters) { Object result = null; try { WebResource webResource = _client.resource(_baseUrl + path); ClientResponse response = null; if (null == parameters) response = webResource.header("cookie", _authToken).get(ClientResponse.class); else response = webResource.queryParams(parameters).header("cookie", _authToken).get(ClientResponse.class); String entity = response.getEntity(String.class); JSONObject jsonObject = (JSONObject)_parser.parse(new StringReader(entity)); result = findObject(jsonObject, resource); } catch (Exception ex) { ex.printStackTrace(); } return result; } /** * Convenience method to recursively find a object with an key * traversing down from a given root object. This will traverse a * JSONObject / JSONArray recursively to find a matching key, if found * the object with the key is returned. * @param root root object which contains the key searched for * @param key the key for the object to search for * @return the object matching the key */ private Object findObject(Object root, String key) { Object result = null; if (root instanceof JSONObject) { JSONObject rootJSON = (JSONObject)root; if (rootJSON.containsKey(key)) { result = rootJSON.get(key); } else { Iterator children = rootJSON.entrySet().iterator(); while (children.hasNext()) { Map.Entry entry = (Map.Entry)children.next(); Object child = entry.getValue(); if (child instanceof JSONObject || child instanceof JSONArray) { result = findObject(child, key); if (null != result) break; } } } } else if (root instanceof JSONArray) { JSONArray rootJSON = (JSONArray)root; for (Object child : rootJSON) { if (child instanceof JSONObject || child instanceof JSONArray) { result = findObject(child, key); if (null != result) break; } } } return result; } }   Creating Business Objects While JCS application can be created without a local database, the local database is required when using ADFbc objects even if database objects are not referred. For this example we will create a "Transient" view object that will be programmatically populated based the data obtained from Taleo REST services. Creating ADFbc objects Choose the "Model" project and navigate "New -> Business Tier : ADF Business Components : View Object". On the "Initialize Business Components Project" choose the local database connection created in previous step. On Step 1 enter "JcsRestDemoVO" on the "Name" and choose "Rows populated programmatically, not based on query": On step 2 create the following attributes: CandId Type: Number Updatable: Always Key Attribute: checked Name Type: String Updatable: Always On steps 3 and 4 accept defaults and click "Next".  On step 5 check the "Application Module" checkbox and enter "JcsRestDemoAM" as the name: Click "Finish" to generate the objects. Populating the VO To display the data on the UI the "transient VO" is populated programmatically based on the data obtained from the Taleo REST services. Open the "JcsRestDemoVOImpl.java". Copy / paste the following as the content (for details of the implementation refer to the documentation in the code): import java.sql.ResultSet; import java.util.List; import java.util.ListIterator; import oracle.jbo.server.ViewObjectImpl; import oracle.jbo.server.ViewRowImpl; import oracle.jbo.server.ViewRowSetImpl; // --------------------------------------------------------------------- // --- File generated by Oracle ADF Business Components Design Time. // --- Tue Feb 18 09:40:25 PST 2014 // --- Custom code may be added to this class. // --- Warning: Do not modify method signatures of generated methods. // --------------------------------------------------------------------- public class JcsRestDemoVOImpl extends ViewObjectImpl { /** * This is the default constructor (do not remove). */ public JcsRestDemoVOImpl() { } @Override public void executeQuery() { /** * For some reason we need to reset everything, otherwise * 2nd entry to the UI screen may fail with * "java.util.NoSuchElementException" in createRowFromResultSet * call to "candidates.next()". I am not sure why this is happening * as the Iterator is new and "hasNext" is true at the point * of the execution. My theory is that since the iterator object is * exactly the same the VO cache somehow reuses the iterator including * the pointer that has already exhausted the iterable elements on the * previous run. Working around the issue * here by cleaning out everything on the VO every time before query * is executed on the VO. */ getViewDef().setQuery(null); getViewDef().setSelectClause(null); setQuery(null); this.reset(); this.clearCache(); super.executeQuery(); } /** * executeQueryForCollection - overridden for custom java data source support. */ protected void executeQueryForCollection(Object qc, Object[] params, int noUserParams) { /** * Integrate with the Taleo REST services using TaleoRepository class. * A list of candidates matching a hard coded query is obtained. */ TaleoRepository repository = new TaleoRepository(<company>, <username>, <password>); List<Candidate> candidates = repository.getCandidates(); /** * Store iterator for the candidates as user data on the collection. * This will be used in createRowFromResultSet to create rows based on * the custom iterator. */ ListIterator<Candidate> candidatescIterator = candidates.listIterator(); setUserDataForCollection(qc, candidatescIterator); super.executeQueryForCollection(qc, params, noUserParams); } /** * hasNextForCollection - overridden for custom java data source support. */ protected boolean hasNextForCollection(Object qc) { boolean result = false; /** * Determines whether there are candidates for which to create a row */ ListIterator<Candidate> candidates = (ListIterator<Candidate>)getUserDataForCollection(qc); result = candidates.hasNext(); /** * If all candidates to be created indicate that processing is done */ if (!result) { setFetchCompleteForCollection(qc, true); } return result; } /** * createRowFromResultSet - overridden for custom java data source support. */ protected ViewRowImpl createRowFromResultSet(Object qc, ResultSet resultSet) { /** * Obtain the next candidate from the collection and create a row * for it. */ ListIterator<Candidate> candidates = (ListIterator<Candidate>)getUserDataForCollection(qc); ViewRowImpl row = createNewRowForCollection(qc); try { Candidate candidate = candidates.next(); row.setAttribute("CandId", candidate.getCandId()); row.setAttribute("Name", candidate.getFirstName() + " " + candidate.getLastName()); } catch (Exception e) { e.printStackTrace(); } return row; } /** * getQueryHitCount - overridden for custom java data source support. */ public long getQueryHitCount(ViewRowSetImpl viewRowSet) { /** * For this example this is not implemented rather we always return 0. */ return 0; } } Creating UI Choose the "ViewController" project and navigate "New -> Web Tier : JSF : JSF Page". On the "Create JSF Page" enter "JcsRestDemo" as name and ensure that the "Create as XML document (*.jspx)" is checked.  Open "JcsRestDemo.jspx" and navigate to "Data Controls -> JcsRestDemoAMDataControl -> JcsRestDemoVO1" and drag & drop the VO to the "<af:form> " as a "ADF Read-only Table": Accept the defaults in "Edit Table Columns". To execute the query navigate to to "Data Controls -> JcsRestDemoAMDataControl -> JcsRestDemoVO1 -> Operations -> Execute" and drag & drop the operation to the "<af:form> " as a "Button": Deploying to JCS Follow the same steps as documented in previous article"Java Cloud Service ADF Web Application". Once deployed the application can be accessed with URL: https://java-[identity domain].java.[data center].oraclecloudapps.com/JcsRestDemo-ViewController-context-root/faces/JcsRestDemo.jspx The UI displays a list of candidates obtained from the Taleo REST Services: Summary In this article we learned how to integrate with REST services using Jersey library in JCS. In future articles various other integration techniques will be covered.

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  • ls -l freezes terminal locally and remotely

    - by Jakobud
    I've been reading other SF threads regarding ls not returning results or freezing and stalling terminal sessions and it appears they usually the fault of network problems. My problem however, occurs both over remote SSH sessions but also if I am physically at the server itself... I just installed CentOS 5.4 on one of our servers. I'm setting up some rdiff-backup scripts and when I downloaded librsync and untared it, thats when I started seeing some weird behavior with ls -l. wget http://sourceforge.net/projects/librsync/files/librsync/0.9.7/librsync-0.9.7.tar.gz/download /tmp cd /tmp tar -xzf librsync-0.9.7.tar.gz Simple enough. To view the files in this directory I did this: ls results: librsync-0.9.7 librsync-0.9.7.tar.gz Now, if I ls -l, my terminal freezes. I have to re-ssh in to keep going. After reading SF threads, I thought it was network related. So I was extremely surprised to go sit down at the server itself and see the exact same thing happen... So its obviously not a network issues. Even if I ls /tmp/librsync-0.9.7, my terminal freezes just the same... Next I did an strace and got this (warning: wall of text coming....): strace ls -l /tmp execve("/bin/ls", ["ls", "-l", "/tmp"], [/* 21 vars */]) = 0 brk(0) = 0x1c521000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b8582cc0000 uname({sys="Linux", node="massive.answeron.com", ...}) = 0 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory) open("/etc/ld.so.cache", O_RDONLY) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=71746, ...}) = 0 mmap(NULL, 71746, PROT_READ, MAP_PRIVATE, 3, 0) = 0x2b8582cc1000 close(3) = 0 open("/lib64/librt.so.1", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0 \"\200\2730\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=53448, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b8582cd3000 mmap(0x30bb800000, 2132936, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x30bb800000 mprotect(0x30bb807000, 2097152, PROT_NONE) = 0 mmap(0x30bba07000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x7000) = 0x30bba07000 close(3) = 0 open("/lib64/libacl.so.1", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0\31@\2740\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=28008, ...}) = 0 mmap(0x30bc400000, 2120992, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x30bc400000 mprotect(0x30bc406000, 2093056, PROT_NONE) = 0 mmap(0x30bc605000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x5000) = 0x30bc605000 close(3) = 0 open("/lib64/libselinux.so.1", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0`E\300\2730\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=95464, ...}) = 0 mmap(0x30bbc00000, 2192784, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x30bbc00000 mprotect(0x30bbc15000, 2097152, PROT_NONE) = 0 mmap(0x30bbe15000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x15000) = 0x30bbe15000 mmap(0x30bbe17000, 1424, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x30bbe17000 close(3) = 0 open("/lib64/libc.so.6", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\220\332\201\2720\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=1717800, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b8582cd4000 mmap(0x30ba800000, 3498328, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x30ba800000 mprotect(0x30ba94d000, 2097152, PROT_NONE) = 0 mmap(0x30bab4d000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x14d000) = 0x30bab4d000 mmap(0x30bab52000, 16728, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x30bab52000 close(3) = 0 open("/lib64/libpthread.so.0", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\220W\0\2730\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=145824, ...}) = 0 mmap(0x30bb000000, 2204528, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x30bb000000 mprotect(0x30bb016000, 2093056, PROT_NONE) = 0 mmap(0x30bb215000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x15000) = 0x30bb215000 mmap(0x30bb217000, 13168, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x30bb217000 close(3) = 0 open("/lib64/libattr.so.1", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\320\17\300\2750\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=17888, ...}) = 0 mmap(0x30bdc00000, 2110728, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x30bdc00000 mprotect(0x30bdc04000, 2093056, PROT_NONE) = 0 mmap(0x30bde03000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3000) = 0x30bde03000 close(3) = 0 open("/lib64/libdl.so.2", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\20\16\300\2720\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=23360, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b8582cd5000 mmap(0x30bac00000, 2109696, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x30bac00000 mprotect(0x30bac02000, 2097152, PROT_NONE) = 0 mmap(0x30bae02000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x30bae02000 close(3) = 0 open("/lib64/libsepol.so.1", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0=\0\2740\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=247496, ...}) = 0 mmap(0x30bc000000, 2383136, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x30bc000000 mprotect(0x30bc03b000, 2097152, PROT_NONE) = 0 mmap(0x30bc23b000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3b000) = 0x30bc23b000 mmap(0x30bc23c000, 40224, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x30bc23c000 close(3) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b8582cd6000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b8582cd7000 arch_prctl(ARCH_SET_FS, 0x2b8582cd6c50) = 0 mprotect(0x30bba07000, 4096, PROT_READ) = 0 mprotect(0x30bab4d000, 16384, PROT_READ) = 0 mprotect(0x30bb215000, 4096, PROT_READ) = 0 mprotect(0x30ba61b000, 4096, PROT_READ) = 0 mprotect(0x30bae02000, 4096, PROT_READ) = 0 munmap(0x2b8582cc1000, 71746) = 0 set_tid_address(0x2b8582cd6ce0) = 24102 set_robust_list(0x2b8582cd6cf0, 0x18) = 0 futex(0x7fff72d02d6c, FUTEX_WAKE_PRIVATE, 1) = 0 rt_sigaction(SIGRTMIN, {0x30bb005370, [], SA_RESTORER|SA_SIGINFO, 0x30bb00e7c0}, NULL, 8) = 0 rt_sigaction(SIGRT_1, {0x30bb0052b0, [], SA_RESTORER|SA_RESTART|SA_SIGINFO, 0x30bb00e7c0}, NULL, 8) = 0 rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0 getrlimit(RLIMIT_STACK, {rlim_cur=10240*1024, rlim_max=RLIM_INFINITY}) = 0 access("/etc/selinux/", F_OK) = 0 brk(0) = 0x1c521000 brk(0x1c542000) = 0x1c542000 open("/etc/selinux/config", O_RDONLY) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=448, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b8582cc1000 read(3, "# This file controls the state o"..., 4096) = 448 read(3, "", 4096) = 0 close(3) = 0 munmap(0x2b8582cc1000, 4096) = 0 open("/proc/mounts", O_RDONLY) = 3 fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b8582cc1000 read(3, "rootfs / rootfs rw 0 0\n/dev/root"..., 4096) = 577 close(3) = 0 munmap(0x2b8582cc1000, 4096) = 0 open("/selinux/mls", O_RDONLY) = 3 read(3, "1", 19) = 1 close(3) = 0 socket(PF_FILE, SOCK_STREAM, 0) = 3 connect(3, {sa_family=AF_FILE, path="/var/run/setrans/.setrans-unix"...}, 110) = 0 sendmsg(3, {msg_name(0)=NULL, msg_iov(5)=[{"\1\0\0\0", 4}, {"\1\0\0\0", 4}, {"\1\0\0\0", 4}, {"\0", 1}, {"\0", 1}], msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 14 readv(3, [{"\1\0\0\0", 4}, {"\1\0\0\0", 4}, {"\0\0\0\0", 4}], 3) = 12 readv(3, [{"\0", 1}], 1) = 1 close(3) = 0 open("/usr/lib/locale/locale-archive", O_RDONLY) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=56413824, ...}) = 0 mmap(NULL, 56413824, PROT_READ, MAP_PRIVATE, 3, 0) = 0x2b8582cd8000 close(3) = 0 ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0 ioctl(1, TIOCGWINSZ, {ws_row=65, ws_col=137, ws_xpixel=0, ws_ypixel=0}) = 0 open("/usr/share/locale/locale.alias", O_RDONLY) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=2528, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(3, "# Locale name alias data base.\n#"..., 4096) = 2528 read(3, "", 4096) = 0 close(3) = 0 munmap(0x2b85862a5000, 4096) = 0 open("/usr/share/locale/en_US.UTF-8/LC_TIME/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en_US.utf8/LC_TIME/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en_US/LC_TIME/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en.UTF-8/LC_TIME/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en.utf8/LC_TIME/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/share/locale/en/LC_TIME/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory) lstat("/tmp", {st_mode=S_IFDIR|S_ISVTX|0777, st_size=4096, ...}) = 0 getxattr("/tmp", "system.posix_acl_access", 0x0, 0) = -1 ENODATA (No data available) getxattr("/tmp", "system.posix_acl_default", 0x0, 0) = -1 ENODATA (No data available) socket(PF_FILE, SOCK_STREAM, 0) = 3 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(3, {sa_family=AF_FILE, path="/var/run/nscd/socket"...}, 110) = -1 ENOENT (No such file or directory) close(3) = 0 socket(PF_FILE, SOCK_STREAM, 0) = 3 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(3, {sa_family=AF_FILE, path="/var/run/nscd/socket"...}, 110) = -1 ENOENT (No such file or directory) close(3) = 0 open("/etc/nsswitch.conf", O_RDONLY) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=1711, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(3, "#\n# /etc/nsswitch.conf\n#\n# An ex"..., 4096) = 1711 read(3, "", 4096) = 0 close(3) = 0 munmap(0x2b85862a5000, 4096) = 0 open("/etc/ld.so.cache", O_RDONLY) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=71746, ...}) = 0 mmap(NULL, 71746, PROT_READ, MAP_PRIVATE, 3, 0) = 0x2b85862a5000 close(3) = 0 open("/lib64/libnss_files.so.2", O_RDONLY) = 3 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\340\37\0\0\0\0\0\0"..., 832) = 832 fstat(3, {st_mode=S_IFREG|0755, st_size=53880, ...}) = 0 mmap(NULL, 2139432, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x2b85862b7000 mprotect(0x2b85862c1000, 2093056, PROT_NONE) = 0 mmap(0x2b85864c0000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x9000) = 0x2b85864c0000 close(3) = 0 mprotect(0x2b85864c0000, 4096, PROT_READ) = 0 munmap(0x2b85862a5000, 71746) = 0 open("/etc/passwd", O_RDONLY) = 3 fcntl(3, F_GETFD) = 0 fcntl(3, F_SETFD, FD_CLOEXEC) = 0 fstat(3, {st_mode=S_IFREG|0644, st_size=1823, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(3, "root:x:0:0:root:/root:/bin/bash\n"..., 4096) = 1823 close(3) = 0 munmap(0x2b85862a5000, 4096) = 0 socket(PF_FILE, SOCK_STREAM, 0) = 3 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(3, {sa_family=AF_FILE, path="/var/run/nscd/socket"...}, 110) = -1 ENOENT (No such file or directory) close(3) = 0 socket(PF_FILE, SOCK_STREAM, 0) = 3 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(3, {sa_family=AF_FILE, path="/var/run/nscd/socket"...}, 110) = -1 ENOENT (No such file or directory) close(3) = 0 open("/etc/group", O_RDONLY) = 3 fcntl(3, F_GETFD) = 0 fcntl(3, F_SETFD, FD_CLOEXEC) = 0 fstat(3, {st_mode=S_IFREG|0644, st_size=743, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(3, "root:x:0:root\nbin:x:1:root,bin,d"..., 4096) = 743 close(3) = 0 munmap(0x2b85862a5000, 4096) = 0 open("/tmp", O_RDONLY|O_NONBLOCK|O_DIRECTORY) = 3 fcntl(3, F_SETFD, FD_CLOEXEC) = 0 getdents(3, /* 8 entries */, 32768) = 264 lstat("/tmp/librsync-0.9.7.tar.gz", {st_mode=S_IFREG|0644, st_size=453802, ...}) = 0 getxattr("/tmp/librsync-0.9.7.tar.gz", "system.posix_acl_access", 0x0, 0) = -1 ENODATA (No data available) getxattr("/tmp/librsync-0.9.7.tar.gz", "system.posix_acl_default", 0x0, 0) = -1 ENODATA (No data available) lstat("/tmp/librsync-0.9.7", {st_mode=S_IFDIR|0777, st_size=4096, ...}) = 0 getxattr("/tmp/librsync-0.9.7", "system.posix_acl_access", 0x0, 0) = -1 ENODATA (No data available) getxattr("/tmp/librsync-0.9.7", "system.posix_acl_default", 0x0, 0) = -1 ENODATA (No data available) open("/etc/passwd", O_RDONLY) = 4 fcntl(4, F_GETFD) = 0 fcntl(4, F_SETFD, FD_CLOEXEC) = 0 fstat(4, {st_mode=S_IFREG|0644, st_size=1823, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(4, "root:x:0:0:root:/root:/bin/bash\n"..., 4096) = 1823 read(4, "", 4096) = 0 close(4) = 0 munmap(0x2b85862a5000, 4096) = 0 open("/etc/ld.so.cache", O_RDONLY) = 4 fstat(4, {st_mode=S_IFREG|0644, st_size=71746, ...}) = 0 mmap(NULL, 71746, PROT_READ, MAP_PRIVATE, 4, 0) = 0x2b85862a5000 close(4) = 0 open("/lib64/libnss_ldap.so.2", O_RDONLY) = 4 read(4, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\300r\4\0\0\0\0\0"..., 832) = 832 fstat(4, {st_mode=S_IFREG|0755, st_size=3169960, ...}) = 0 mmap(NULL, 5329912, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 4, 0) = 0x2b85864c2000 mprotect(0x2b858679e000, 2093056, PROT_NONE) = 0 mmap(0x2b858699d000, 176128, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 4, 0x2db000) = 0x2b858699d000 mmap(0x2b85869c8000, 62456, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x2b85869c8000 close(4) = 0 open("/lib64/libcom_err.so.2", O_RDONLY) = 4 read(4, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\320\n\300\2770\0\0\0"..., 832) = 832 fstat(4, {st_mode=S_IFREG|0755, st_size=10000, ...}) = 0 mmap(0x30bfc00000, 2103048, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 4, 0) = 0x30bfc00000 mprotect(0x30bfc02000, 2093056, PROT_NONE) = 0 mmap(0x30bfe01000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 4, 0x1000) = 0x30bfe01000 close(4) = 0 open("/lib64/libkeyutils.so.1", O_RDONLY) = 4 read(4, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0`\n@\2760\0\0\0"..., 832) = 832 fstat(4, {st_mode=S_IFREG|0755, st_size=9472, ...}) = 0 mmap(0x30be400000, 2102416, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 4, 0) = 0x30be400000 mprotect(0x30be402000, 2093056, PROT_NONE) = 0 mmap(0x30be601000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 4, 0x1000) = 0x30be601000 close(4) = 0 open("/lib64/libresolv.so.2", O_RDONLY) = 4 read(4, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\2402\0\2760\0\0\0"..., 832) = 832 fstat(4, {st_mode=S_IFREG|0755, st_size=92736, ...}) = 0 mmap(0x30be000000, 2181864, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 4, 0) = 0x30be000000 mprotect(0x30be011000, 2097152, PROT_NONE) = 0 mmap(0x30be211000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 4, 0x11000) = 0x30be211000 mmap(0x30be213000, 6888, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x30be213000 close(4) = 0 mprotect(0x30be211000, 4096, PROT_READ) = 0 munmap(0x2b85862a5000, 71746) = 0 rt_sigaction(SIGPIPE, {0x1, [], SA_RESTORER, 0x30ba8302d0}, {SIG_DFL, [], 0}, 8) = 0 geteuid() = 0 futex(0x2b85869c7708, FUTEX_WAKE_PRIVATE, 2147483647) = 0 open("/etc/ldap.conf", O_RDONLY) = 4 fstat(4, {st_mode=S_IFREG|0644, st_size=9119, ...}) = 0 fstat(4, {st_mode=S_IFREG|0644, st_size=9119, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(4, "# @(#)$Id: ldap.conf,v 1.38 2006"..., 4096) = 4096 read(4, "Use the OpenLDAP password change"..., 4096) = 4096 read(4, " OpenLDAP 2.0 and earlier is \"no"..., 4096) = 927 read(4, "", 4096) = 0 close(4) = 0 munmap(0x2b85862a5000, 4096) = 0 uname({sys="Linux", node="massive.answeron.com", ...}) = 0 open("/etc/resolv.conf", O_RDONLY) = 4 fstat(4, {st_mode=S_IFREG|0644, st_size=107, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(4, "; generated by /sbin/dhclient-sc"..., 4096) = 107 read(4, "", 4096) = 0 close(4) = 0 munmap(0x2b85862a5000, 4096) = 0 socket(PF_FILE, SOCK_STREAM, 0) = 4 fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(4, {sa_family=AF_FILE, path="/var/run/nscd/socket"...}, 110) = -1 ENOENT (No such file or directory) close(4) = 0 socket(PF_FILE, SOCK_STREAM, 0) = 4 fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(4, {sa_family=AF_FILE, path="/var/run/nscd/socket"...}, 110) = -1 ENOENT (No such file or directory) close(4) = 0 open("/etc/host.conf", O_RDONLY) = 4 fstat(4, {st_mode=S_IFREG|0644, st_size=17, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(4, "order hosts,bind\n", 4096) = 17 read(4, "", 4096) = 0 close(4) = 0 munmap(0x2b85862a5000, 4096) = 0 futex(0x30bab54d44, FUTEX_WAKE_PRIVATE, 2147483647) = 0 open("/etc/hosts", O_RDONLY) = 4 fcntl(4, F_GETFD) = 0 fcntl(4, F_SETFD, FD_CLOEXEC) = 0 fstat(4, {st_mode=S_IFREG|0644, st_size=187, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(4, "# Do not remove the following li"..., 4096) = 187 read(4, "", 4096) = 0 close(4) = 0 munmap(0x2b85862a5000, 4096) = 0 open("/etc/ld.so.cache", O_RDONLY) = 4 fstat(4, {st_mode=S_IFREG|0644, st_size=71746, ...}) = 0 mmap(NULL, 71746, PROT_READ, MAP_PRIVATE, 4, 0) = 0x2b85862a5000 close(4) = 0 open("/lib64/libnss_dns.so.2", O_RDONLY) = 4 read(4, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\340\17\0\0\0\0\0\0"..., 832) = 832 fstat(4, {st_mode=S_IFREG|0755, st_size=23736, ...}) = 0 mmap(NULL, 2113792, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 4, 0) = 0x2b85869d8000 mprotect(0x2b85869dc000, 2093056, PROT_NONE) = 0 mmap(0x2b8586bdb000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 4, 0x3000) = 0x2b8586bdb000 close(4) = 0 mprotect(0x2b8586bdb000, 4096, PROT_READ) = 0 munmap(0x2b85862a5000, 71746) = 0 socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 4 connect(4, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("192.168.10.20")}, 28) = 0 fcntl(4, F_GETFL) = 0x2 (flags O_RDWR) fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0 gettimeofday({1276265920, 823870}, NULL) = 0 poll([{fd=4, events=POLLOUT}], 1, 0) = 1 ([{fd=4, revents=POLLOUT}]) sendto(4, "C\v\1\0\0\1\0\0\0\0\0\0\7massive\10answeron\3co"..., 38, MSG_NOSIGNAL, NULL, 0) = 38 poll([{fd=4, events=POLLIN}], 1, 5000) = 1 ([{fd=4, revents=POLLIN}]) ioctl(4, FIONREAD, [122]) = 0 recvfrom(4, "C\v\205\200\0\1\0\1\0\2\0\2\7massive\10answeron\3co"..., 1024, 0, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("192.168.10.20")}, [16]) = 122 close(4) = 0 open("/etc/openldap/ldap.conf", O_RDONLY) = 4 fstat(4, {st_mode=S_IFREG|0644, st_size=335, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(4, "#\n# LDAP Defaults\n#\n\n# See ldap."..., 4096) = 335 read(4, "", 4096) = 0 close(4) = 0 munmap(0x2b85862a5000, 4096) = 0 getuid() = 0 geteuid() = 0 getgid() = 0 getegid() = 0 open("/root/ldaprc", O_RDONLY) = -1 ENOENT (No such file or directory) open("/root/.ldaprc", O_RDONLY) = -1 ENOENT (No such file or directory) stat("/etc/ldap.conf", {st_mode=S_IFREG|0644, st_size=9119, ...}) = 0 geteuid() = 0 brk(0x1c566000) = 0x1c566000 open("/etc/hosts", O_RDONLY) = 4 fcntl(4, F_GETFD) = 0 fcntl(4, F_SETFD, FD_CLOEXEC) = 0 fstat(4, {st_mode=S_IFREG|0644, st_size=187, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(4, "# Do not remove the following li"..., 4096) = 187 read(4, "", 4096) = 0 close(4) = 0 munmap(0x2b85862a5000, 4096) = 0 open("/etc/hosts", O_RDONLY) = 4 fcntl(4, F_GETFD) = 0 fcntl(4, F_SETFD, FD_CLOEXEC) = 0 fstat(4, {st_mode=S_IFREG|0644, st_size=187, ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2b85862a5000 read(4, "# Do not remove the following li"..., 4096) = 187 read(4, "", 4096) = 0 close(4) = 0 munmap(0x2b85862a5000, 4096) = 0 socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 4 connect(4, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("192.168.10.20")}, 28) = 0 fcntl(4, F_GETFL) = 0x2 (flags O_RDWR) fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0 gettimeofday({1276265920, 855948}, NULL) = 0 poll([{fd=4, events=POLLOUT}], 1, 0) = 1 ([{fd=4, revents=POLLOUT}]) sendto(4, "\32 \1\0\0\1\0\0\0\0\0\0\4ldap\10answeron\3com\0\0"..., 35, MSG_NOSIGNAL, NULL, 0) = 35 poll([{fd=4, events=POLLIN}], 1, 5000) = 1 ([{fd=4, revents=POLLIN}]) ioctl(4, FIONREAD, [104]) = 0 recvfrom(4, "\32 \205\200\0\1\0\1\0\1\0\0\4ldap\10answeron\3com\0\0"..., 1024, 0, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("192.168.10.20")}, [16]) = 104 close(4) = 0 socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 4 connect(4, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("192.168.10.20")}, 28) = 0 fcntl(4, F_GETFL) = 0x2 (flags O_RDWR) fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0 gettimeofday({1276265920, 858536}, NULL) = 0 poll([{fd=4, events=POLLOUT}], 1, 0) = 1 ([{fd=4, revents=POLLOUT}]) sendto(4, "I\375\1\0\0\1\0\0\0\0\0\0\4ldap\10answeron\3com\0\0"..., 35, MSG_NOSIGNAL, NULL, 0) = 35 poll([{fd=4, events=POLLIN}], 1, 5000) = 1 ([{fd=4, revents=POLLIN}]) ioctl(4, FIONREAD, [139]) = 0 recvfrom(4, "I\375\205\200\0\1\0\2\0\2\0\2\4ldap\10answeron\3com\0\0"..., 1024, 0, {sa_family=AF_INET, sin_port=htons(53), sin_addr=inet_addr("192.168.10.20")}, [16]) = 139 close(4) = 0 socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 4 fcntl(4, F_SETFD, FD_CLOEXEC) = 0 setsockopt(4, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0 setsockopt(4, SOL_TCP, TCP_NODELAY, [1], 4) = 0 fcntl(4, F_GETFL) = 0x2 (flags O_RDWR) fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(4, {sa_family=AF_INET, sin_port=htons(389), sin_addr=inet_addr("10.20.0.30")}, 16) = -1 EINPROGRESS (Operation now in progress) poll([{fd=4, events=POLLOUT|POLLERR|POLLHUP}], 1, 120000 And thats where it stops, right there after that last 120000.... Using strace, I can obviously CTRL+C to keep going. But like I said, normally the terminal completely freezes. Anyone have any clues?

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  • Building applications with WCF - Intro

    - by skjagini
    I am going to write series of articles using Windows Communication Framework (WCF) to develop client and server applications and this is the first part of that series. What is WCF As Juwal puts in his Programming WCF book, WCF provides an SDK for developing and deploying services on Windows, provides runtime environment to expose CLR types as services and consume services as CLR types. Building services with WCF is incredibly easy and it’s implementation provides a set of industry standards and off the shelf plumbing including service hosting, instance management, reliability, transaction management, security etc such that it greatly increases productivity Scenario: Lets consider a typical bank customer trying to create an account, deposit amount and transfer funds between accounts, i.e. checking and savings. To make it interesting, we are going to divide the functionality into multiple services and each of them working with database directly. We will run test cases with and without transactional support across services. In this post we will build contracts, services, data access layer, unit tests to verify end to end communication etc, nothing big stuff here and we dig into other features of the WCF in subsequent posts with incremental changes. In any distributed architecture we have two pieces i.e. services and clients. Services as the name implies provide functionality to execute various pieces of business logic on the server, and clients providing interaction to the end user. Services can be built with Web Services or with WCF. Service built on WCF have the advantage of binding independent, i.e. can run against TCP and HTTP protocol without any significant changes to the code. Solution Services Profile: For creating a new bank customer, getting details about existing customer ProfileContract ProfileService Checking Account: To get checking account balance, deposit or withdraw amount CheckingAccountContract CheckingAccountService Savings Account: To get savings account balance, deposit or withdraw amount SavingsAccountContract SavingsAccountService ServiceHost: To host services, i.e. running the services at particular address, binding and contract where client can connect to Client: Helps end user to use services like creating account and amount transfer between the accounts BankDAL: Data access layer to work with database     BankDAL It’s no brainer not to use an ORM as many matured products are available currently in market including Linq2Sql, Entity Framework (EF), LLblGenPro etc. For this exercise I am going to use Entity Framework 4.0, CTP 5 with code first approach. There are two approaches when working with data, data driven and code driven. In data driven we start by designing tables and their constrains in database and generate entities in code while in code driven (code first) approach entities are defined in code and the metadata generated from the entities is used by the EF to create tables and table constrains. In previous versions the entity classes had  to derive from EF specific base classes. In EF 4 it  is not required to derive from any EF classes, the entities are not only persistence ignorant but also enable full test driven development using mock frameworks.  Application consists of 3 entities, Customer entity which contains Customer details; CheckingAccount and SavingsAccount to hold the respective account balance. We could have introduced an Account base class for CheckingAccount and SavingsAccount which is certainly possible with EF mappings but to keep it simple we are just going to follow 1 –1 mapping between entity and table mappings. Lets start out by defining a class called Customer which will be mapped to Customer table, observe that the class is simply a plain old clr object (POCO) and has no reference to EF at all. using System;   namespace BankDAL.Model { public class Customer { public int Id { get; set; } public string FullName { get; set; } public string Address { get; set; } public DateTime DateOfBirth { get; set; } } }   In order to inform EF about the Customer entity we have to define a database context with properties of type DbSet<> for every POCO which needs to be mapped to a table in database. EF uses convention over configuration to generate the metadata resulting in much less configuration. using System.Data.Entity;   namespace BankDAL.Model { public class BankDbContext: DbContext { public DbSet<Customer> Customers { get; set; } } }   Entity constrains can be defined through attributes on Customer class or using fluent syntax (no need to muscle with xml files), CustomerConfiguration class. By defining constrains in a separate class we can maintain clean POCOs without corrupting entity classes with database specific information.   using System; using System.Data.Entity.ModelConfiguration;   namespace BankDAL.Model { public class CustomerConfiguration: EntityTypeConfiguration<Customer> { public CustomerConfiguration() { Initialize(); }   private void Initialize() { //Setting the Primary Key this.HasKey(e => e.Id);   //Setting required fields this.HasRequired(e => e.FullName); this.HasRequired(e => e.Address); //Todo: Can't create required constraint as DateOfBirth is not reference type, research it //this.HasRequired(e => e.DateOfBirth); } } }   Any queries executed against Customers property in BankDbContext are executed against Cusomers table. By convention EF looks for connection string with key of BankDbContext when working with the context.   We are going to define a helper class to work with Customer entity with methods for querying, adding new entity etc and these are known as repository classes, i.e., CustomerRepository   using System; using System.Data.Entity; using System.Linq; using BankDAL.Model;   namespace BankDAL.Repositories { public class CustomerRepository { private readonly IDbSet<Customer> _customers;   public CustomerRepository(BankDbContext bankDbContext) { if (bankDbContext == null) throw new ArgumentNullException(); _customers = bankDbContext.Customers; }   public IQueryable<Customer> Query() { return _customers; }   public void Add(Customer customer) { _customers.Add(customer); } } }   From the above code it is observable that the Query methods returns customers as IQueryable i.e. customers are retrieved only when actually used i.e. iterated. Returning as IQueryable also allows to execute filtering and joining statements from business logic using lamba expressions without cluttering the data access layer with tens of methods.   Our CheckingAccountRepository and SavingsAccountRepository look very similar to each other using System; using System.Data.Entity; using System.Linq; using BankDAL.Model;   namespace BankDAL.Repositories { public class CheckingAccountRepository { private readonly IDbSet<CheckingAccount> _checkingAccounts;   public CheckingAccountRepository(BankDbContext bankDbContext) { if (bankDbContext == null) throw new ArgumentNullException(); _checkingAccounts = bankDbContext.CheckingAccounts; }   public IQueryable<CheckingAccount> Query() { return _checkingAccounts; }   public void Add(CheckingAccount account) { _checkingAccounts.Add(account); }   public IQueryable<CheckingAccount> GetAccount(int customerId) { return (from act in _checkingAccounts where act.CustomerId == customerId select act); }   } } The repository classes look very similar to each other for Query and Add methods, with the help of C# generics and implementing repository pattern (Martin Fowler) we can reduce the repeated code. Jarod from ElegantCode has posted an article on how to use repository pattern with EF which we will implement in the subsequent articles along with WCF Unity life time managers by Drew Contracts It is very easy to follow contract first approach with WCF, define the interface and append ServiceContract, OperationContract attributes. IProfile contract exposes functionality for creating customer and getting customer details.   using System; using System.ServiceModel; using BankDAL.Model;   namespace ProfileContract { [ServiceContract] public interface IProfile { [OperationContract] Customer CreateCustomer(string customerName, string address, DateTime dateOfBirth);   [OperationContract] Customer GetCustomer(int id);   } }   ICheckingAccount contract exposes functionality for working with checking account, i.e., getting balance, deposit and withdraw of amount. ISavingsAccount contract looks the same as checking account.   using System.ServiceModel;   namespace CheckingAccountContract { [ServiceContract] public interface ICheckingAccount { [OperationContract] decimal? GetCheckingAccountBalance(int customerId);   [OperationContract] void DepositAmount(int customerId,decimal amount);   [OperationContract] void WithdrawAmount(int customerId, decimal amount);   } }   Services   Having covered the data access layer and contracts so far and here comes the core of the business logic, i.e. services.   .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } ProfileService implements the IProfile contract for creating customer and getting customer detail using CustomerRepository. using System; using System.Linq; using System.ServiceModel; using BankDAL; using BankDAL.Model; using BankDAL.Repositories; using ProfileContract;   namespace ProfileService { [ServiceBehavior(IncludeExceptionDetailInFaults = true)] public class Profile: IProfile { public Customer CreateAccount( string customerName, string address, DateTime dateOfBirth) { Customer cust = new Customer { FullName = customerName, Address = address, DateOfBirth = dateOfBirth };   using (var bankDbContext = new BankDbContext()) { new CustomerRepository(bankDbContext).Add(cust); bankDbContext.SaveChanges(); } return cust; }   public Customer CreateCustomer(string customerName, string address, DateTime dateOfBirth) { return CreateAccount(customerName, address, dateOfBirth); } public Customer GetCustomer(int id) { return new CustomerRepository(new BankDbContext()).Query() .Where(i => i.Id == id).FirstOrDefault(); }   } } From the above code you shall observe that we are calling bankDBContext’s SaveChanges method and there is no save method specific to customer entity because EF manages all the changes centralized at the context level and all the pending changes so far are submitted in a batch and it is represented as Unit of Work. Similarly Checking service implements ICheckingAccount contract using CheckingAccountRepository, notice that we are throwing overdraft exception if the balance falls by zero. WCF has it’s own way of raising exceptions using fault contracts which will be explained in the subsequent articles. SavingsAccountService is similar to CheckingAccountService. using System; using System.Linq; using System.ServiceModel; using BankDAL.Model; using BankDAL.Repositories; using CheckingAccountContract;   namespace CheckingAccountService { [ServiceBehavior(IncludeExceptionDetailInFaults = true)] public class Checking:ICheckingAccount { public decimal? GetCheckingAccountBalance(int customerId) { using (var bankDbContext = new BankDbContext()) { CheckingAccount account = (new CheckingAccountRepository(bankDbContext) .GetAccount(customerId)).FirstOrDefault();   if (account != null) return account.Balance;   return null; } }   public void DepositAmount(int customerId, decimal amount) { using(var bankDbContext = new BankDbContext()) { var checkingAccountRepository = new CheckingAccountRepository(bankDbContext); CheckingAccount account = (checkingAccountRepository.GetAccount(customerId)) .FirstOrDefault();   if (account == null) { account = new CheckingAccount() { CustomerId = customerId }; checkingAccountRepository.Add(account); }   account.Balance = account.Balance + amount; if (account.Balance < 0) throw new ApplicationException("Overdraft not accepted");   bankDbContext.SaveChanges(); } } public void WithdrawAmount(int customerId, decimal amount) { DepositAmount(customerId, -1*amount); } } }   BankServiceHost The host acts as a glue binding contracts with it’s services, exposing the endpoints. The services can be exposed either through the code or configuration file, configuration file is preferred as it allows run time changes to service behavior even after deployment. We have 3 services and for each of the service you need to define name (the class that implements the service with fully qualified namespace) and endpoint known as ABC, i.e. address, binding and contract. We are using netTcpBinding and have defined the base address with for each of the contracts .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } <system.serviceModel> <services> <service name="ProfileService.Profile"> <endpoint binding="netTcpBinding" contract="ProfileContract.IProfile"/> <host> <baseAddresses> <add baseAddress="net.tcp://localhost:1000/Profile"/> </baseAddresses> </host> </service> <service name="CheckingAccountService.Checking"> <endpoint binding="netTcpBinding" contract="CheckingAccountContract.ICheckingAccount"/> <host> <baseAddresses> <add baseAddress="net.tcp://localhost:1000/Checking"/> </baseAddresses> </host> </service> <service name="SavingsAccountService.Savings"> <endpoint binding="netTcpBinding" contract="SavingsAccountContract.ISavingsAccount"/> <host> <baseAddresses> <add baseAddress="net.tcp://localhost:1000/Savings"/> </baseAddresses> </host> </service> </services> </system.serviceModel> Have to open the services by creating service host which will handle the incoming requests from clients.   using System;   namespace ServiceHost { class Program { static void Main(string[] args) { CreateHosts(); Console.ReadLine(); }   private static void CreateHosts() { CreateHost(typeof(ProfileService.Profile),"Profile Service"); CreateHost(typeof(SavingsAccountService.Savings), "Savings Account Service"); CreateHost(typeof(CheckingAccountService.Checking), "Checking Account Service"); }   private static void CreateHost(Type type, string hostDescription) { System.ServiceModel.ServiceHost host = new System.ServiceModel.ServiceHost(type); host.Open();   if (host.ChannelDispatchers != null && host.ChannelDispatchers.Count != 0 && host.ChannelDispatchers[0].Listener != null) Console.WriteLine("Started: " + host.ChannelDispatchers[0].Listener.Uri); else Console.WriteLine("Failed to start:" + hostDescription); } } } BankClient    The client has no knowledge about service business logic other than the functionality it exposes through the contract, end points and a proxy to work against. The endpoint data and server proxy can be generated by right clicking on the project reference and choosing ‘Add Service Reference’ and entering the service end point address. Or if you have access to source, you can manually reference contract dlls and update clients configuration file to point to the service end point if the server and client happens to be being built using .Net framework. One of the pros with the manual approach is you don’t have to work against messy code generated files.   <system.serviceModel> <client> <endpoint name="tcpProfile" address="net.tcp://localhost:1000/Profile" binding="netTcpBinding" contract="ProfileContract.IProfile"/> <endpoint name="tcpCheckingAccount" address="net.tcp://localhost:1000/Checking" binding="netTcpBinding" contract="CheckingAccountContract.ICheckingAccount"/> <endpoint name="tcpSavingsAccount" address="net.tcp://localhost:1000/Savings" binding="netTcpBinding" contract="SavingsAccountContract.ISavingsAccount"/>   </client> </system.serviceModel> The client uses a façade to connect to the services   using System.ServiceModel; using CheckingAccountContract; using ProfileContract; using SavingsAccountContract;   namespace Client { public class ProxyFacade { public static IProfile ProfileProxy() { return (new ChannelFactory<IProfile>("tcpProfile")).CreateChannel(); }   public static ICheckingAccount CheckingAccountProxy() { return (new ChannelFactory<ICheckingAccount>("tcpCheckingAccount")) .CreateChannel(); }   public static ISavingsAccount SavingsAccountProxy() { return (new ChannelFactory<ISavingsAccount>("tcpSavingsAccount")) .CreateChannel(); }   } }   With that in place, lets get our unit tests going   using System; using System.Diagnostics; using BankDAL.Model; using NUnit.Framework; using ProfileContract;   namespace Client { [TestFixture] public class Tests { private void TransferFundsFromSavingsToCheckingAccount(int customerId, decimal amount) { ProxyFacade.CheckingAccountProxy().DepositAmount(customerId, amount); ProxyFacade.SavingsAccountProxy().WithdrawAmount(customerId, amount); }   private void TransferFundsFromCheckingToSavingsAccount(int customerId, decimal amount) { ProxyFacade.SavingsAccountProxy().DepositAmount(customerId, amount); ProxyFacade.CheckingAccountProxy().WithdrawAmount(customerId, amount); }     [Test] public void CreateAndGetProfileTest() { IProfile profile = ProxyFacade.ProfileProxy(); const string customerName = "Tom"; int customerId = profile.CreateCustomer(customerName, "NJ", new DateTime(1982, 1, 1)).Id; Customer customer = profile.GetCustomer(customerId); Assert.AreEqual(customerName,customer.FullName); }   [Test] public void DepositWithDrawAndTransferAmountTest() { IProfile profile = ProxyFacade.ProfileProxy(); string customerName = "Smith" + DateTime.Now.ToString("HH:mm:ss"); var customer = profile.CreateCustomer(customerName, "NJ", new DateTime(1982, 1, 1)); // Deposit to Savings ProxyFacade.SavingsAccountProxy().DepositAmount(customer.Id, 100); ProxyFacade.SavingsAccountProxy().DepositAmount(customer.Id, 25); Assert.AreEqual(125, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id)); // Withdraw ProxyFacade.SavingsAccountProxy().WithdrawAmount(customer.Id, 30); Assert.AreEqual(95, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id));   // Deposit to Checking ProxyFacade.CheckingAccountProxy().DepositAmount(customer.Id, 60); ProxyFacade.CheckingAccountProxy().DepositAmount(customer.Id, 40); Assert.AreEqual(100, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id)); // Withdraw ProxyFacade.CheckingAccountProxy().WithdrawAmount(customer.Id, 30); Assert.AreEqual(70, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id));   // Transfer from Savings to Checking TransferFundsFromSavingsToCheckingAccount(customer.Id,10); Assert.AreEqual(85, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id)); Assert.AreEqual(80, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id));   // Transfer from Checking to Savings TransferFundsFromCheckingToSavingsAccount(customer.Id, 50); Assert.AreEqual(135, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customer.Id)); Assert.AreEqual(30, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customer.Id)); }   [Test] public void FundTransfersWithOverDraftTest() { IProfile profile = ProxyFacade.ProfileProxy(); string customerName = "Angelina" + DateTime.Now.ToString("HH:mm:ss");   var customerId = profile.CreateCustomer(customerName, "NJ", new DateTime(1972, 1, 1)).Id;   ProxyFacade.SavingsAccountProxy().DepositAmount(customerId, 100); TransferFundsFromSavingsToCheckingAccount(customerId,80); Assert.AreEqual(20, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customerId)); Assert.AreEqual(80, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customerId));   try { TransferFundsFromSavingsToCheckingAccount(customerId,30); } catch (Exception e) { Debug.WriteLine(e.Message); }   Assert.AreEqual(110, ProxyFacade.CheckingAccountProxy().GetCheckingAccountBalance(customerId)); Assert.AreEqual(20, ProxyFacade.SavingsAccountProxy().GetSavingsAccountBalance(customerId)); } } }   We are creating a new instance of the channel for every operation, we will look into instance management and how creating a new instance of channel affects it in subsequent articles. The first two test cases deals with creation of Customer, deposit and withdraw of month between accounts. The last case, FundTransferWithOverDraftTest() is interesting. Customer starts with depositing $100 in SavingsAccount followed by transfer of $80 in to checking account resulting in $20 in savings account.  Customer then initiates $30 transfer from Savings to Checking resulting in overdraft exception on Savings with $30 being deposited to Checking. As we are not running both the requests in transactions the customer ends up with more amount than what he started with $100. In subsequent posts we will look into transactions handling.  Make sure the ServiceHost project is set as start up project and start the solution. Run the test cases either from NUnit client or TestDriven.Net/Resharper which ever is your favorite tool. Make sure you have updated the data base connection string in the ServiceHost config file to point to your local database

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