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• StackOverFlowError while creating Mac object on AS400/Java

  - by Prasanna K Rao

  Hello all, I am a newbie to AS400-Java programming. I am trying to create my first program to test the implementation of Message Authentication Code (MAC). I am trying to use the HMACSHA1 hash function. My (Java 1.4) program runs fine on a dev box (V5R4).But fails terribly on the QA box (V5R3). My program is as below: ===================================================== import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import java.security.Security; import java.security.Provider; import javax.crypto.Mac; import javax.crypto.spec.SecretKeySpec; import javax.crypto.SecretKey; public class Test01 { private static final String HMAC_SHA1_ALGORITHM = "HmacSHA1"; public static void main (String [] arguments) { byte[] key = { 1,2,3,4,5,6,7,8}; SecretKeySpec SHA1key = new SecretKeySpec(key, "HmacSHA1"); Mac hmac; String strFinalRslt = ""; try { hmac = Mac.getInstance("HmacSHA1"); hmac.init(SHA1key); byte[] result = hmac.doFinal(); strFinalRslt = toHexString(result); }catch (NoSuchAlgorithmException e) { // TODO Auto-generated catch block e.printStackTrace(); }catch (InvalidKeyException e) { // TODO Auto-generated catch block e.printStackTrace(); }catch(StackOverflowError e){ e.printStackTrace(); } System.out.println(strFinalRslt); System.out.println("All done!!!"); } public static byte[] fromHexString ( String s ) { int stringLength = s.length(); if ( (stringLength & 0x1) != 0 ) { throw new IllegalArgumentException ( "fromHexString requires an even number of hex characters" ); } byte[] b = new byte[stringLength / 2]; for ( int i=0,j=0; i 4] ); //look up low nibble char sb.append( hexChar [b[i] & 0x0f] ); } return sb.toString(); } static char[] hexChar = { '0' , '1' , '2' , '3' , '4' , '5' , '6' , '7' , '8' , '9' , 'a' , 'b' , 'c' , 'd' , 'e' , 'f'}; } This program compiles fine and gets the correct response on my win-xp client and also my dev box. But, fails with the following error on the QA box: java.lang.StackOverflowError at java.lang.Throwable.(Throwable.java:180) at java.lang.Error.(Error.java:37) at java.lang.StackOverflowError.(StackOverflowError.java:24) at java.io.Os400FileSystem.list(Native method) at java.io.File.list(File.java:922) at javax.crypto.b.e(Unknown source) at javax.crypto.b.a(Unknown source) at javax.crypto.b.c(Unknown source) at javax.crypto.b£0.run(Unknown source) at javax.crypto.b.(Unknown source) at javax.crypto.Mac.getInstance(Unknown source) I have verified the java.security file and entry corresponding to the jce files are all ok. The DMPJVM command gives me the following response: Thu Jun 03 12:25:34 E Java Virtual Machine Information 016822/QPGMR/11111 ........................................................................ . Classpath . ........................................................................ java.version=1.4 sun.boot.class.path=/QIBM/ProdData/OS400/Java400/jdk/lib/jdkptf14.zip:/QIBM /ProdData/OS400/Java400/ext/ibmjssefw.jar:/QIBM/ProdData/CAP/ibmjsseprovide r.jar:/QIBM/ProdData/OS400/Java400/ext/ibmjsseprovider2.jar:/QIBM/ProdData/ OS400/Java400/ext/ibmpkcs11impl.jar:/QIBM/ProdData/CAP/ibmjssefips.jar:/QIB M/ProdData/OS400/Java400/jdk/lib/IBMiSeriesJSSE.jar:/QIBM/ProdData/OS400/Ja va400/jdk/lib/jce.jar:/QIBM/ProdData/OS400/Java400/jdk/lib/jaas.jar:/QIBM/P rodData/OS400/Java400/jdk/lib/ibmcertpathfw.jar:/QIBM/ProdData/OS400/Java40 0/jdk/lib/ibmcertpathprovider.jar:/QIBM/ProdData/OS400/Java400/ext/ibmpkcs. jar:/QIBM/ProdData/OS400/Java400/jdk/lib/ibmjgssfw.jar:/QIBM/ProdData/OS400 /Java400/jdk/lib/ibmjgssprovider.jar:/QIBM/ProdData/OS400/Java400/jdk/lib/s ecurity.jar:/QIBM/ProdData/OS400/Java400/jdk/lib/charsets.jar:/QIBM/ProdDat a/OS400/Java400/jdk/lib/resources.jar:/QIBM/ProdData/OS400/Java400/jdk/lib/ rt.jar:/QIBM/ProdData/OS400/Java400/jdk/lib/sunrsasign.jar:/QIBM/ProdData/O S400/Java400/ext/IBMmisc.jar:/QIBM/ProdData/Java400/ java.class.path=/myhome/lib/commons-codec-1.3.jar:/myhome/lib/commons-httpc lient-3.1.jar:/myhome/lib/commons-logging-1.1.jar:/myhome/lib/log4j-1.2.15.jar:/myhome/lib/log4j-core.jar ; java.ext.dirs=/QIBM/ProdData/OS400/Java400/jdk/lib/ext:/QIBM/UserData/Java4 00/ext:/QIBM/ProdData/Java400/jdk14/lib/ext java.library.path=/QSYS.LIB/ROBOTLIB.LIB:/QSYS.LIB/QTEMP.LIB:/QSYS.LIB/ODIP GM.LIB:/QSYS.LIB/QGPL.LIB ........................................................................ . Garbage Collection . ........................................................................ Garbage collector parameters Initial size: 16384 K Max size: 240000000 K Current values Heap size: 437952 K Garbage collections: 58 Additional values JIT heap size: 53824 K JVM heap size: 55752 K Last GC cycle time: 1333 ms ........................................................................ . Thread information . ........................................................................ Information for 4 thread(s) of 4 thread(s) processed Thread: 00000004 Thread-0 TDE: B00380000BAA0000 Thread priority: 5 Thread status: Running Thread group: main Runnable: java/lang/Thread Stack: java/io/Os400FileSystem.list(Ljava/io/File;)[Ljava/lang/String;+0 (Os400FileSystem.java:0) java/io/File.list()[Ljava/lang/String;+19 (File.java:922) javax/crypto/b.e()[B+127 (:0) javax/crypto/b.a(Ljava/security/cert/X509Certificate;)V+7 (:0) javax/crypto/b.access$500(Ljava/security/cert/X509Certificate;)V+1 (:0) javax/crypto/b$0.run()Ljava/lang/Object;+98 (:0) javax/crypto/b.()V+507 (:0) javax/crypto/Mac.getInstance(Ljava/lang/String;)Ljavax/crypto/Mac;+10 (:0) Locks: None Thread: 00000007 jitcompilethread TDE: B00380000BD58000 Thread priority: 5 Thread status: Java wait Thread group: system Runnable: java/lang/Thread Stack: None Locks: None Thread: 00000005 Reference Handler TDE: B00380000BAAC000 Thread priority: 10 Thread status: Waiting Wait object: java/lang/ref/Reference$Lock Thread group: system Runnable: java/lang/ref/Reference$ReferenceHandler Stack: java/lang/Object.wait()V+1 (Object.java:452) java/lang/ref/Reference$ReferenceHandler.run()V+47 (Reference.java:169) Locks: None Thread: 00000006 Finalizer TDE: B00380000BAB3000 Thread priority: 8 Thread status: Waiting Wait object: java/lang/ref/ReferenceQueue$Lock Thread group: system Runnable: java/lang/ref/Finalizer$FinalizerThread Stack: java/lang/ref/ReferenceQueue.remove(J)Ljava/lang/ref/Reference;+43 (ReferenceQueue.java:111) java/lang/ref/ReferenceQueue.remove()Ljava/lang/ref/Reference;+1 (ReferenceQueue.java:127) java/lang/ref/Finalizer$FinalizerThread.run()V+3 (Finalizer.java:171) Locks: None ........................................................................ . Class loader information . ........................................................................ 0 Default class loader 1 sun/reflect/DelegatingClassLoader 2 sun/misc/Launcher$ExtClassLoader ........................................................................ . GC heap information . ........................................................................ Loader Objects Class name ------ ------- ---------- 0 1493 [C 0 2122181 java/lang/String 0 47 [Ljava/util/Hashtable$Entry; 0 68 [Ljava/lang/Object; 0 1016 java/lang/Class 0 31 java/util/HashMap 0 37 java/util/Hashtable 0 2 java/lang/ThreadGroup 0 2 java/lang/RuntimePermission 0 2 java/lang/ref/ReferenceQueue$Null 0 5 java/lang/ref/ReferenceQueue 0 50 java/util/Vector 0 4 java/util/Stack 0 3 sun/misc/SoftCache 0 1 [Ljava/lang/ThreadGroup; 0 5 [Ljava/io/ObjectStreamField; 0 1 sun/reflect/ReflectionFactory 0 7 java/lang/ref/ReferenceQueue$Lock 0 10 java/lang/Object 0 1 java/lang/String$CaseInsensitiveComparator 0 1 java/util/Hashtable$EmptyEnumerator 0 1 java/util/Hashtable$EmptyIterator 0 33 [Ljava/util/HashMap$Entry; 0 19210 [J 0 1 sun/nio/cs/StandardCharsets 0 5 java/util/TreeMap 0 1075 java/util/TreeMap$Entry 0 469 [Ljava/lang/String; 0 1 java/lang/StringBuffer 0 2 java/io/FileInputStream 0 2 java/io/FileOutputStream 0 2 java/io/BufferedOutputStream 0 1 java/lang/reflect/ReflectPermission 0 1 [[Ljava/lang/ref/SoftReference; 0 2 [Ljava/lang/ref/SoftReference; 0 2 sun/nio/cs/Surrogate$Parser 0 3 sun/misc/Signal 0 1 [Ljava/io/File; 0 6 java/io/File 0 1 java/util/BitSet 0 17 sun/reflect/NativeConstructorAccessorImpl 0 2 java/net/URLClassLoader$ClassFinder 0 12 java/util/ArrayList 0 32 java/io/RandomAccessFile 0 16 java/lang/Thread 0 1 java/lang/ref/Reference$ReferenceHandler 0 1 java/lang/ref/Finalizer$FinalizerThread 0 266 [B 0 2 java/util/Properties 0 71 java/lang/ref/Finalizer 0 2 com/ibm/nio/cs/DirectEncoder 0 38 java/lang/reflect/Constructor 0 33 java/util/jar/JarFile 0 19200 java/lang/StackOverflowError 0 5 java/security/AccessControlContext 0 2 [Ljava/lang/Thread; 0 4 java/lang/OutOfMemoryError 0 1065 java/util/Hashtable$Entry 0 1 java/io/BufferedInputStream 0 2 java/io/PrintStream 0 2 java/io/OutputStreamWriter 0 428 [I 0 3 java/lang/ClassLoader$NativeLibrary 0 25 java/util/Locale 0 3 sun/misc/URLClassPath 0 30 java/util/zip/Inflater 0 612 java/util/HashMap$Entry 0 2 java/io/FilePermission 0 10 java/io/ObjectStreamField 0 1 java/security/BasicPermissionCollection 0 2 java/security/ProtectionDomain 0 1 java/lang/Integer$1 0 1 java/lang/ref/Reference$Lock 0 1 java/lang/Shutdown$Lock 0 1 java/lang/Runtime 0 36 java/io/FileDescriptor 0 1 java/lang/Long$1 0 202 java/lang/Long 0 3 java/lang/ThreadLocal 0 3 java/nio/charset/CodingErrorAction 0 2 java/nio/charset/CoderResult 0 1 java/nio/charset/CoderResult$1 0 1 java/nio/charset/CoderResult$2 0 1 sun/misc/Unsafe 0 2 java/nio/ByteOrder 0 1 java/io/Os400FileSystem 0 3 java/lang/Boolean 0 1 java/lang/Terminator$1 0 23 java/lang/Integer 0 2 sun/misc/NativeSignalHandler 0 1 sun/misc/Launcher$Factory 0 1 sun/misc/Launcher 0 53 [Ljava/lang/Class; 0 1 java/lang/reflect/ReflectAccess 0 18 sun/reflect/DelegatingConstructorAccessorImpl 0 1 sun/net/www/protocol/file/Handler 0 3 java/util/HashSet 0 3 sun/net/www/protocol/jar/Handler 0 1 java/util/jar/JavaUtilJarAccessImpl 0 1 java/net/UnknownContentHandler 0 2 [Ljava/security/Principal; 0 10 [Ljava/security/cert/Certificate; 0 2 sun/misc/AtomicLongCSImpl 0 3 sun/reflect/DelegatingMethodAccessorImpl 0 1 sun/security/util/ByteArrayLexOrder 0 1 sun/security/util/ByteArrayTagOrder 0 7 sun/security/x509/CertificateVersion 0 7 sun/security/x509/CertificateSerialNumber 0 7 sun/security/x509/SerialNumber 0 7 sun/security/x509/CertificateAlgorithmId 0 7 sun/security/x509/CertificateIssuerName 0 60 sun/security/x509/RDN 0 60 [Lsun/security/x509/AVA; 0 67 sun/security/util/DerInputStream 0 3 [Ljava/math/BigInteger; 0 2 com/ibm/nio/cs/Converter 0 2 sun/nio/cs/StreamEncoder$CharsetSE 0 35 java/lang/ref/SoftReference 0 2 java/nio/HeapByteBuffer 0 2 java/io/BufferedWriter 0 33 sun/misc/URLClassPath$JarLoader 0 4 java/lang/ThreadLocal$ThreadLocalMap$Entry 0 76 java/net/URL 0 1 sun/misc/Launcher$ExtClassLoader 0 1 sun/misc/Launcher$AppClassLoader 0 4 java/lang/Throwable 0 7 java/lang/reflect/Method 0 2 sun/misc/URLClassPath$FileLoader 0 2 java/security/CodeSource 0 2 java/security/Permissions 0 2 java/io/FilePermissionCollection 0 1 java/lang/ThreadLocal$ThreadLocalMap 0 1 javax/crypto/spec/SecretKeySpec 0 17 java/util/jar/Attributes$Name 0 1 [Ljava/lang/ThreadLocal$ThreadLocalMap$Entry; 0 1 java/security/SecureRandom 0 2 sun/security/provider/Sun 0 1 java/util/jar/JarFile$JarFileEntry 0 1 java/util/jar/JarVerifier 0 3 sun/reflect/NativeMethodAccessorImpl 0 116 sun/security/util/ObjectIdentifier 0 1 java/lang/Package 0 2 [S 0 104 java/math/BigInteger 0 20 sun/security/x509/AlgorithmId 0 14 sun/security/x509/X500Name 0 14 [Lsun/security/x509/RDN; 0 60 sun/security/x509/AVA 0 67 sun/security/util/DerValue 0 67 sun/security/util/DerInputBuffer 0 21 sun/security/x509/AVAKeyword 0 6 sun/security/x509/X509CertImpl 0 7 sun/security/x509/X509CertInfo 0 1 [Lsun/security/util/ObjectIdentifier; 0 1 [[Ljava/lang/Byte; 0 3 [[B 0 7 sun/security/provider/DSAPublicKey 0 7 sun/security/x509/AuthorityKeyIdentifierExtension 0 12 [Ljava/lang/Byte; 0 14 java/lang/Byte 0 7 sun/security/x509/CertificateSubjectName 0 7 sun/security/x509/CertificateX509Key 0 14 sun/security/x509/KeyIdentifier 0 4 [Z 0 5 sun/text/Normalizer$Mode 0 7 sun/security/x509/CertificateValidity 0 14 java/util/Date 0 7 sun/security/provider/DSAParameters 0 7 sun/security/util/BitArray 0 7 sun/security/x509/CertificateExtensions 0 7 java/security/AlgorithmParameters 0 7 sun/security/x509/SubjectKeyIdentifierExtension 0 5 sun/security/x509/BasicConstraintsExtension 0 2 sun/security/x509/KeyUsageExtension 0 1 sun/text/CompactCharArray 0 1 sun/text/CompactByteArray 0 1 sun/net/www/protocol/jar/JarFileFactory 0 1 java/util/Collections$EmptySet 0 1 java/util/Collections$EmptyList 0 1 java/util/Collections$ReverseComparator 0 1 com/ibm/security/jgss/i18n/PropertyResource 0 1 javax/crypto/b$0 0 1 sun/security/provider/X509Factory 0 1 sun/reflect/BootstrapConstructorAccessorImpl 1 1 sun/reflect/GeneratedConstructorAccessor3202134454 2 1 com/ibm/crypto/provider/IBMJCE 0 6 java/util/ResourceBundle$LoaderReference 0 1 [Lsun/security/x509/NetscapeCertTypeExtension$MapEntry; 0 1 com/sun/rsajca/Provider 0 1 com/ibm/security/cert/IBMCertPath 0 1 com/ibm/as400/ibmonly/net/ssl/Provider 0 1 com/ibm/jsse/IBMJSSEProvider 0 1 com/ibm/security/jgss/IBMJGSSProvider 0 5 org/ietf/jgss/Oid 0 1 java/util/PropertyResourceBundle 0 7 java/util/ResourceBundle$ResourceCacheKey 0 2 sun/net/www/protocol/jar/URLJarFile 0 6 sun/misc/SoftCache$ValueCell 0 1 java/util/Random 0 1 java/util/Collections$EmptyMap 0 112 com/ibm/security/util/ObjectIdentifier 0 5 java/security/Security$ProviderProperty 0 1 java/security/cert/CertificateFactory 0 1 sun/security/provider/SecureRandom 0 2 java/security/MessageDigest$Delegate 0 2 sun/security/provider/SHA 0 1 sun/util/calendar/ZoneInfo 0 4 com/ibm/security/x509/X500Name 0 2 [Ljava/security/cert/X509Certificate; 0 1 sun/reflect/DelegatingClassLoader 0 1 sun/security/x509/NetscapeCertTypeExtension 0 7 sun/security/x509/NetscapeCertTypeExtension$MapEntry 0 3 [[Ljava/lang/String; 0 3 java/util/Arrays$ArrayList 0 7 com/ibm/security/x509/NetscapeCertTypeExtension$MapEntry 0 1 com/ibm/security/validator/EndEntityChecker 0 1 java/util/AbstractList$Itr 0 1 com/ibm/security/util/ByteArrayLexOrder 0 1 com/ibm/security/util/ByteArrayTagOrder 0 18 [Lcom/ibm/security/x509/AVA; 0 18 com/ibm/security/util/DerInputStream 0 5 com/ibm/security/util/text/Normalizer$Mode 0 1 com/ibm/security/validator/SimpleValidator 0 1 [Lcom/ibm/security/x509/NetscapeCertTypeExtension$MapEntry; 0 4 [Lcom/ibm/security/x509/RDN; 0 1 java/util/Hashtable$Enumerator 0 4 java/util/LinkedHashMap$Entry 0 1 sun/text/resources/LocaleElements 0 1 sun/text/resources/LocaleElements_en 0 22 com/ibm/security/x509/AVAKeyword 0 4 javax/security/auth/x500/X500Principal 0 18 com/ibm/security/x509/RDN 0 18 com/ibm/security/x509/AVA 0 18 com/ibm/security/util/DerInputBuffer 0 18 com/ibm/security/util/DerValue 0 1 com/ibm/security/util/text/CompactCharArray 0 1 com/ibm/security/util/text/CompactByteArray 0 2 java/util/LinkedHashMap 0 1 java/net/InetAddress$1 0 2 [Ljava/net/InetAddress; 0 2 java/net/InetAddress$Cache 0 1 java/net/Inet4AddressImpl 0 3 java/net/Inet4Address 0 2 java/net/InetAddress$CacheEntry ........................................................................ . Global registry information . ........................................................................ Loader Objects Class name ------ ------- ---------- 0 23 [C 0 1017 java/lang/Class 0 1 java/lang/ref/Reference$ReferenceHandler 0 1 java/lang/ref/Finalizer$FinalizerThread 0 1 sun/misc/Launcher$AppClassLoader 0 32 java/io/RandomAccessFile 0 32 [B Can someone please advise me? Thanks a lot, Prasanna

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• Help with Collapse and Expand Accordion at same time using JQuery (demo)

  - by Evan

  I'm stuck on an Expand/Collapse accordion using JQuery. After the initial headline is clicked and it expands, if you click to another headline it will collapse the former headline completely FIRST then it will expand the headline you clicked. This collapse first then expand second technique is very distracting and what should happen is as the headline is expanding it should collapse the initial headline. What am I missing? You can experience a demo here: http://media.apus.edu/it/evan-testing/accordion.htm Below is all my work Javascript <script src="http://www.apus.edu/bin/l/y/jquery-1.3.2.min.js" type="text/javascript"></script> <script type="text/javascript"> //<!-- $(document).ready(function() { $(".accordian>li.expanded").removeClass("expanded"); $(".accordian>li h2").addClass("jse").click(function() { var doOpen = !$(this).parent().hasClass('expanded'); var openContainers = $(".accordian>li.expanded").length>0; var targetNode = this; if(openContainers) { $(".accordian>li.expanded h2") .parent() .removeClass('expanded') .end() .nextAll() .slideUp(100,function(){ if($(".accordian>li.expanded").length==0) performOpen(doOpen,targetNode); }); } else { performOpen(doOpen,targetNode); } // if containers are open, proceed on callback // else proceed immediately }).nextAll().slideUp(100); }); function performOpen(doOpen,whichNode) { if(doOpen) { $('html,body').animate({scrollTop: $(whichNode).offset().top}, 1000); //target code $(whichNode).nextAll().slideDown(100).parent().addClass('expanded'); } } //--> </script> CSS <style> .accordian { list-style : none; padding : 0px; margin : 0px; font-size : 12px; } .accordian li { list-style : none; padding : 0px; margin : 0px; } .accordian li a:hover { text-decoration : underline; } .accordian li h2 { cursor : auto; text-decoration : none; padding : 0px 0px 4px 22px; } .accordian li h2.jse { background-image : url(http://www.apus.edu/bin/m/p/toggle_arrow.gif); background-position : 4px -35px; background-repeat : no-repeat; } .accordian li h2:hover { cursor : pointer; text-decoration : underline; } .accordian li li { margin-bottom : 5px; margin-left : 0px; margin-top : 0px; padding : 0px; } .accordian li p { display : block; padding-top : 0px; padding-bottom : 15px; padding-left : 10px; margin-left : 30px; margin-top : 0px; } .accordian li ul { margin-bottom : 30px; margin-top : 0px; padding-top : 0px; padding-left : 0px; margin-left : 0px; } .accordian li.expanded h2.jse { background-position : 4px -5px; } .accordianContainer { margin-top : 0px; padding-top : 0px; } .accordianContainer h2 { padding : 3px; } .accordian_nolist { list-style : none; } </style> HTML <table height="120"><tr><td>&nbsp;</td></tr></table> <div class="accordianContainer"> <ul class="accordian"> <li><h2>Title 1 Goes here - Example</h2> <ul><li> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> </li></ul> </li> </ul> </div> <div class="accordianContainer"> <ul class="accordian"> <li><h2>Title 2 Goes here - Example</h2> <ul><li> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> </li></ul> </li> </ul> </div> <div class="accordianContainer"> <ul class="accordian"> <li><h2>Title 3 Goes here - Example</h2> <ul><li> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> </li></ul> </li> </ul> </div> <div class="accordianContainer"> <ul class="accordian"> <li><h2>Title 4 Goes here - Example</h2> <ul><li> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> </li></ul> </li> </ul> </div> <div class="accordianContainer"> <ul class="accordian"> <li><h2>Title 5 Goes here - Example</h2> <ul><li> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> this is where content goes<BR>this is where content goes<BR>this is where content goes<BR> </li></ul> </li> </ul> </div>

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• Rails link to PDF version of show.html.erb

  - by Danny McClelland

  Hi Everyone, I have created a pdf version of our rails application using the Prawn plugin, the page in question is part of the Kase model - the link to the kase is /kases/1 and the link to the pdf version is /kases/1.pdf. How can I add a link within the show.html.erb to the PDF file so whichever page is being viewed it updates the URL to the correct case id? <% content_for :header do -%> <%=h @kase.jobno %> | <%=h @kase.casesubject %> <% end -%> <!-- #START SIDEBAR --> <% content_for :sidebar do -%> <% if @kase.avatar.exists? then %> <%= image_tag @kase.avatar.url %> <% else %> <p style="font-size:smaller"> You can upload an icon for this case that will display here. Usually this would be for the year number icon for easy recognition.</p> <% end %> <% end %> <!-- #END SIDEBAR --> <ul id="kases_showlist"> <li>Date Instructed: <span><%=h @kase.dateinstructed %></span></li> <li>Client Company: <span><%=h @kase.clientcompanyname %></span></li> <li>Client Reference: <span><%=h @kase.clientref %></span></li> <li>Case Subject: <span><%=h @kase.casesubject %></span></li> <li>Transport<span><%=h @kase.transport %></span></li> <li>Goods<span><%=h @kase.goods %></span></li> <li>Case Status: <span><%=h @kase.kase_status %></span></li> <li>Client Company Address: <span class="address"><%=h @kase.clientcompanyaddress %></span></li> <li>Client Company Fax: <span><%=h @kase.clientcompanyfax %></span></li> <li>Case Handler: <span><%=h @kase.casehandlername %></span></li> <li>Case Handler Tel: <span><%=h @kase.casehandlertel %></span></li> <li>Case Handler Email: <span><%=h @kase.casehandleremail %></span></li> <li>Claimant Name: <span><%=h @kase.claimantname %></span></li> <li>Claimant Address: <span class="address"><%=h @kase.claimantaddress %></span></li> <li>Claimant Contact: <span><%=h @kase.claimantcontact %></span></li> <li>Claimant Tel: <span><%=h @kase.claimanttel %></span></li> <li>Claiment Mob: <span><%=h @kase.claimantmob %></span></li> <li>Claiment Email: <span><%=h @kase.claimantemail %></span></li> <li>Claimant URL: <span><%=h @kase.claimanturl %></span></li> <li>Comments: <span><%=h @kase.comments %></span></li> </ul> <!--- START FINANCE INFORMATION --> <div id="kase_finances"> <div class="js_option"> <h2>Financial Options</h2><p class="finance_showhide"><%= link_to_function "Show","Element.show('finance_showhide');" %> / <%= link_to_function "Hide","Element.hide('finance_showhide');" %></p> </div> <div id="finance_showhide" style="display:none"> <ul id="kases_new_finance"> <li>Invoice Number<span><%=h @kase.invoicenumber %></span></li> <li>Net Amount<span><%=h @kase.netamount %></span></li> <li>VAT<span><%=h @kase.vat %></span></li> <li>Gross Amount<span><%=h @kase.grossamount %></span></li> <li>Date Closed<span><%=h @kase.dateclosed %></span></li> <li>Date Paid<span><%=h @kase.datepaid %></span></li> </ul></div> </div> <!--- END FINANCE INFORMATION --> <%= link_to 'Edit Case', edit_kase_path(@kase) %> | <%= link_to 'Back', kases_path %> | <a href="#">Top</a> <div style="width:120%; height: 50px; background-color: black; margin: 10px 0 0 -19px; padding: 0; background-color: #d4d4d4;">&nbsp;</div> <div class="js_option_kaseemails"> <%= link_to_function "Show", "Element.show('newinstructionemail1');" %> / <%= link_to_function "Hide", "Element.hide('newinstructionemail1');" %> </div> <h3>New Instruction Email</h3> <div id="newinstructionemail1" style="display:none"> <p class="kase_email_output"> Hi,<br /> <br /> Many thanks for your instructions in the subject matter.<br /> <br /> We have allocated reference number <%=h @kase.jobno %> to the above claim.<br /> <br /> We have started our inquiries and will be in touch.<br /> <br /> Best Regards,<br /> <br /> <strong><%=h current_user.name %></strong> <br /> McClelland &amp; Co<br /> PO Box 149<br /> Southport<br /> PR8 4GZ<br /> <br /> Tel: +(0) 1704 569871<br /> Fax: +(0) 1704 562234<br /> Mob: <%=h current_user.mobile %><br /> E-mail: <%= current_user.email %><br /> <br /> This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you receive this e-mail in error please notify the originator of the message. <br /><br /> McClelland &amp; Co has taken every reasonable precaution to ensure that any attachment to this e-mail has been checked for viruses but it is strongly recommended that you carry out your own virus check before opening any attachment. McClelland &amp; Co cannot accept liability for any damage sustained as a result of software virus infection. </p> <%= link_to 'Edit Case', edit_kase_path(@kase) %> | <%= link_to 'Back', kases_path %> | <a href="#">Top</a> </div> <div style="width:120%; height: 20px; background-color: black; margin: 10px 0 0 -19px; padding: 0; background-color: #d4d4d4;">&nbsp;</div> <div class="js_option_kaseemails"> <%= link_to_function "Show", "Element.show('newinstructionemail');" %> / <%= link_to_function "Hide", "Element.hide('newinstructionemail');" %> </div> <h3>New Instruction Email</h3> <div id="newinstructionemail" style="display:none"> <p class="kase_email_output"> Hi,<br /> <br /> Many thanks for your instructions in the subject matter.<br /> <br /> We have allocated reference number <%=h @kase.jobno %> to the above claim.<br /> <br /> We have started our inquiries and will be in touch.<br /> <br /> Best Regards,<br /> <br /> <strong><%=h current_user.name %></strong> <br /> McClelland &amp; Co<br /> PO Box 149<br /> Southport<br /> PR8 4GZ<br /> <br /> Tel: +(0) 1704 569871<br /> Fax: +(0) 1704 562234<br /> Mob: <%=h current_user.mobile %><br /> E-mail: <%= current_user.email %><br /> <br /> This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you receive this e-mail in error please notify the originator of the message. <br /><br /> McClelland &amp; Co has taken every reasonable precaution to ensure that any attachment to this e-mail has been checked for viruses but it is strongly recommended that you carry out your own virus check before opening any attachment. McClelland &amp; Co cannot accept liability for any damage sustained as a result of software virus infection. </p> <%= link_to 'Edit Case', edit_kase_path(@kase) %> | <%= link_to 'Back', kases_path %> | <a href="#">Top</a> </div> <div style="width:120%; height: 20px; background-color: black; margin: 10px 0 0 -19px; padding: 0; background-color: #d4d4d4;">&nbsp;</div> <div class="js_option_kaseemails"> <%= link_to_function "Show", "Element.show('newinstructionemail2');" %> / <%= link_to_function "Hide", "Element.hide('newinstructionemail2');" %> </div> <h3>New Instruction Email</h3> <div id="newinstructionemail2" style="display:none;"> <p class="kase_email_output"> Hi,<br /> <br /> Many thanks for your instructions in the subject matter.<br /> <br /> We have allocated reference number <%=h @kase.jobno %> to the above claim.<br /> <br /> We have started our inquiries and will be in touch.<br /> <br /> Best Regards,<br /> <br /> <strong><%=h current_user.name %></strong> <br /> McClelland &amp; Co<br /> PO Box 149<br /> Southport<br /> PR8 4GZ<br /> <br /> Tel: +(0) 1704 569871<br /> Fax: +(0) 1704 562234<br /> Mob: <%=h current_user.mobile %><br /> E-mail: <%= current_user.email %><br /> <br /> This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you receive this e-mail in error please notify the originator of the message. <br /><br /> McClelland &amp; Co has taken every reasonable precaution to ensure that any attachment to this e-mail has been checked for viruses but it is strongly recommended that you carry out your own virus check before opening any attachment. McClelland &amp; Co cannot accept liability for any damage sustained as a result of software virus infection. </p> <%= link_to 'Edit Case', edit_kase_path(@kase) %> | <%= link_to 'Back', kases_path %> | <a href="#">Top</a> </div> Thanks, Danny

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• file doesn't open, running outside of debugger results in seg fault (c++)

  - by misterich

  Hello (and thanks in advance) I'm in a bit of a quandry, I cant seem to figure out why I'm seg faulting. A couple of notes: It's for a course -- and sadly I am required to use use C-strings instead of std::string. Please dont fix my code (I wont learn that way and I will keep bugging you). please just point out the flaws in my logic and suggest a different function/way. platform: gcc version 4.4.1 on Suse Linux 11.2 (2.6.31 kernel) Here's the code main.cpp: // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C/C++ Std Library) #include <cstdlib> /// EXIT_SUCCESS, EXIT_FAILURE #include <iostream> /// cin, cout, ifstream #include <cassert> /// assert // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "dict.h" /// Header for the dictionary class // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR CONSTANTS #define ENTER '\n' /// Used to accept new lines, quit program. #define SPACE ' ' /// One way to end the program // /////////////////////////////////////////////////////////////////////////////////// // CUSTOM DATA TYPES /// File Namespace -- keep it local namespace { /// Possible program prompts to display for the user. enum FNS_Prompts { fileName_, /// prints out the name of the file noFile_, /// no file was passed to the program tooMany_, /// more than one file was passed to the program noMemory_, /// Not enough memory to use the program usage_, /// how to use the program word_, /// ask the user to define a word. notFound_, /// the word is not in the dictionary done_, /// the program is closing normally }; } // /////////////////////////////////////////////////////////////////////////////////// // Namespace using namespace std; /// Nothing special in the way of namespaces // /////////////////////////////////////////////////////////////////////////////////// // FUNCTIONS /** prompt() prompts the user to do something, uses enum Prompts for parameter. */ void prompt(FNS_Prompts msg /** determines the prompt to use*/) { switch(msg) { case fileName_ : { cout << ENTER << ENTER << "The file name is: "; break; } case noFile_ : { cout << ENTER << ENTER << "...Sorry, a dictionary file is needed. Try again." << endl; break; } case tooMany_ : { cout << ENTER << ENTER << "...Sorry, you can only specify one dictionary file. Try again." << endl; break; } case noMemory_ : { cout << ENTER << ENTER << "...Sorry, there isn't enough memory available to run this program." << endl; break; } case usage_ : { cout << "USAGE:" << endl << " lookup.exe [dictionary file name]" << endl << endl; break; } case done_ : { cout << ENTER << ENTER << "like Master P says, \"Word.\"" << ENTER << endl; break; } case word_ : { cout << ENTER << ENTER << "Enter a word in the dictionary to get it's definition." << ENTER << "Enter \"?\" to get a sorted list of all words in the dictionary." << ENTER << "... Press the Enter key to quit the program: "; break; } case notFound_ : { cout << ENTER << ENTER << "...Sorry, that word is not in the dictionary." << endl; break; } default : { cout << ENTER << ENTER << "something passed an invalid enum to prompt(). " << endl; assert(false); /// something passed in an invalid enum } } } /** useDictionary() uses the dictionary created by createDictionary * - prompts user to lookup a word * - ends when the user enters an empty word */ void useDictionary(Dictionary &d) { char *userEntry = new char; /// user's input on the command line if( !userEntry ) // check the pointer to the heap { cout << ENTER << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } do { prompt(word_); // test code cout << endl << "----------------------------------------" << endl << "Enter something: "; cin.getline(userEntry, INPUT_LINE_MAX_LEN, ENTER); cout << ENTER << userEntry << endl; }while ( userEntry[0] != NIL && userEntry[0] != SPACE ); // GARBAGE COLLECTION delete[] userEntry; } /** Program Entry * Reads in the required, single file from the command prompt. * - If there is no file, state such and error out. * - If there is more than one file, state such and error out. * - If there is a single file: * - Create the database object * - Populate the database object * - Prompt the user for entry * main() will return EXIT_SUCCESS upon termination. */ int main(int argc, /// the number of files being passed into the program char *argv[] /// pointer to the filename being passed into tthe program ) { // EXECUTE /* Testing code * / char tempFile[INPUT_LINE_MAX_LEN] = {NIL}; cout << "enter filename: "; cin.getline(tempFile, INPUT_LINE_MAX_LEN, '\n'); */ // uncomment after successful debugging if(argc <= 1) { prompt(noFile_); prompt(usage_); return EXIT_FAILURE; /// no file was passed to the program } else if(argc > 2) { prompt(tooMany_); prompt(usage_); return EXIT_FAILURE; /// more than one file was passed to the program } else { prompt(fileName_); cout << argv[1]; // print out name of dictionary file if( !argv[1] ) { prompt(noFile_); prompt(usage_); return EXIT_FAILURE; /// file does not exist } /* file.open( argv[1] ); // open file numEntries >> in.getline(file); // determine number of dictionary objects to create file.close(); // close file Dictionary[ numEntries ](argv[1]); // create the dictionary object */ // TEMPORARY FILE FOR TESTING!!!! //Dictionary scrabble(tempFile); Dictionary scrabble(argv[1]); // creaate the dicitonary object //*/ useDictionary(scrabble); // prompt the user, use the dictionary } // exit return EXIT_SUCCESS; /// terminate program. } Dict.h/.cpp #ifndef DICT_H #define DICT_H // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (Custom header files) #include "entry.h" /// class for dictionary entries // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define INPUT_LINE_MAX_LEN 256 /// Maximum length of each line in the dictionary file class Dictionary { public : // // Do NOT modify the public section of this class // typedef void (*WordDefFunc)(const char *word, const char *definition); Dictionary( const char *filename ); ~Dictionary(); const char *lookupDefinition( const char *word ); void forEach( WordDefFunc func ); private : // // You get to provide the private members // // VARIABLES int m_numEntries; /// stores the number of entries in the dictionary Entry *m_DictEntry_ptr; /// points to an array of class Entry // Private Functions }; #endif ----------------------------------- // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C/C++ Std Library) #include <iostream> /// cout, getline #include <fstream> // ifstream #include <cstring> /// strchr // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "dict.h" /// Header file required by assignment //#include "entry.h" /// Dicitonary Entry Class // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define COMMA ',' /// Delimiter for file #define ENTER '\n' /// Carriage return character #define FILE_ERR_MSG "The data file could not be opened. Program will now terminate." #pragma warning(disable : 4996) /// turn off MS compiler warning about strcpy() // /////////////////////////////////////////////////////////////////////////////////// // Namespace reference using namespace std; // /////////////////////////////////////////////////////////////////////////////////// // PRIVATE MEMBER FUNCTIONS /** * Sorts the dictionary entries. */ /* static void sortDictionary(?) { // sort through the words using qsort } */ /** NO LONGER NEEDED?? * parses out the length of the first cell in a delimited cell * / int getWordLength(char *str /// string of data to parse ) { return strcspn(str, COMMA); } */ // /////////////////////////////////////////////////////////////////////////////////// // PUBLIC MEMBER FUNCTIONS /** constructor for the class * - opens/reads in file * - creates initializes the array of member vars * - creates pointers to entry objects * - stores pointers to entry objects in member var * - ? sort now or later? */ Dictionary::Dictionary( const char *filename ) { // Create a filestream, open the file to be read in ifstream dataFile(filename, ios::in ); /* if( dataFile.fail() ) { cout << FILE_ERR_MSG << endl; exit(EXIT_FAILURE); } */ if( dataFile.is_open() ) { // read first line of data // TEST CODE in.getline(dataFile, INPUT_LINE_MAX_LEN) >> m_numEntries; // TEST CODE char temp[INPUT_LINE_MAX_LEN] = {NIL}; // TEST CODE dataFile.getline(temp,INPUT_LINE_MAX_LEN,'\n'); dataFile >> m_numEntries; /** Number of terms in the dictionary file * \todo find out how many lines in the file, subtract one, ingore first line */ //create the array of entries m_DictEntry_ptr = new Entry[m_numEntries]; // check for valid memory allocation if( !m_DictEntry_ptr ) { cout << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } // loop thru each line of the file, parsing words/def's and populating entry objects for(int EntryIdx = 0; EntryIdx < m_numEntries; ++EntryIdx) { // VARIABLES char *tempW_ptr; /// points to a temporary word char *tempD_ptr; /// points to a temporary def char *w_ptr; /// points to the word in the Entry object char *d_ptr; /// points to the definition in the Entry int tempWLen; /// length of the temp word string int tempDLen; /// length of the temp def string char tempLine[INPUT_LINE_MAX_LEN] = {NIL}; /// stores a single line from the file // EXECUTE // getline(dataFile, tempLine) // get a "word,def" line from the file dataFile.getline(tempLine, INPUT_LINE_MAX_LEN); // get a "word,def" line from the file // Parse the string tempW_ptr = tempLine; // point the temp word pointer at the first char in the line tempD_ptr = strchr(tempLine, COMMA); // point the def pointer at the comma *tempD_ptr = NIL; // replace the comma with a NIL ++tempD_ptr; // increment the temp def pointer // find the string lengths... +1 to account for terminator tempWLen = strlen(tempW_ptr) + 1; tempDLen = strlen(tempD_ptr) + 1; // Allocate heap memory for the term and defnition w_ptr = new char[ tempWLen ]; d_ptr = new char[ tempDLen ]; // check memory allocation if( !w_ptr && !d_ptr ) { cout << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } // copy the temp word, def into the newly allocated memory and terminate the strings strcpy(w_ptr,tempW_ptr); w_ptr[tempWLen] = NIL; strcpy(d_ptr,tempD_ptr); d_ptr[tempDLen] = NIL; // set the pointers for the entry objects m_DictEntry_ptr[ EntryIdx ].setWordPtr(w_ptr); m_DictEntry_ptr[ EntryIdx ].setDefPtr(d_ptr); } // close the file dataFile.close(); } else { cout << ENTER << FILE_ERR_MSG << endl; exit(EXIT_FAILURE); } } /** * cleans up dynamic memory */ Dictionary::~Dictionary() { delete[] m_DictEntry_ptr; /// thou shalt not have memory leaks. } /** * Looks up definition */ /* const char *lookupDefinition( const char *word ) { // print out the word ---- definition } */ /** * prints out the entire dictionary in sorted order */ /* void forEach( WordDefFunc func ) { // to sort before or now.... that is the question } */ Entry.h/cpp #ifndef ENTRY_H #define ENTRY_H // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C++ Std lib) #include <cstdlib> /// EXIT_SUCCESS, NULL // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define NIL '\0' /// C-String terminator #define MEM_ERR_MSG "Memory allocation has failed. Program will now terminate." // /////////////////////////////////////////////////////////////////////////////////// // CLASS DEFINITION class Entry { public: Entry(void) : m_word_ptr(NULL), m_def_ptr(NULL) { /* default constructor */ }; void setWordPtr(char *w_ptr); /// sets the pointer to the word - only if the pointer is empty void setDefPtr(char *d_ptr); /// sets the ponter to the definition - only if the pointer is empty /// returns what is pointed to by the word pointer char getWord(void) const { return *m_word_ptr; } /// returns what is pointed to by the definition pointer char getDef(void) const { return *m_def_ptr; } private: char *m_word_ptr; /** points to a dictionary word */ char *m_def_ptr; /** points to a dictionary definition */ }; #endif -------------------------------------------------- // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "entry.h" /// class header file // /////////////////////////////////////////////////////////////////////////////////// // PUBLIC FUNCTIONS /* * only change the word member var if it is in its initial state */ void Entry::setWordPtr(char *w_ptr) { if(m_word_ptr == NULL) { m_word_ptr = w_ptr; } } /* * only change the def member var if it is in its initial state */ void Entry::setDefPtr(char *d_ptr) { if(m_def_ptr == NULL) { m_word_ptr = d_ptr; } }

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• Enable Automatic Code First Migrations On SQL Database in Azure Web Sites

  - by Steve Michelotti

  Now that Azure supports .NET Framework 4.5, you can use all the latest and greatest available features. A common scenario is to be able to use Entity Framework Code First Migrations with a SQL Database in Azure. Prior to Code First Migrations, Entity Framework provided database initializers. While convenient for demos and prototypes, database initializers weren’t useful for much beyond that because, if you delete and re-create your entire database when the schema changes, you lose all of your operational data. This is the void that Migrations are meant to fill. For example, if you add a column to your model, Migrations will alter the database to add the column rather than blowing away the entire database and re-creating it from scratch. Azure is becoming increasingly easier to use – especially with features like Azure Web Sites. Being able to use Entity Framework Migrations in Azure makes deployment easier than ever. In this blog post, I’ll walk through enabling Automatic Code First Migrations on Azure. I’ll use the Simple Membership provider for my example. First, we’ll create a new Azure Web site called “migrationstest” including creating a new SQL Database along with it:   Next we’ll go to the web site and download the publish profile:   In the meantime, we’ve created a new MVC 4 website in Visual Studio 2012 using the “Internet Application” template. This template is automatically configured to use the Simple Membership provider. We’ll do our initial Publish to Azure by right-clicking our project and selecting “Publish…”. From the “Publish Web” dialog, we’ll import the publish profile that we downloaded in the previous step:   Once the site is published, we’ll just click the “Register” link from the default site. Since the AccountController is decorated with the [InitializeSimpleMembership] attribute, the initializer will be called and the initial database is created.   We can verify this by connecting to our SQL Database on Azure with SQL Management Studio (after making sure that our local IP address is added to the list of Allowed IP Addresses in Azure): One interesting note is that these tables got created with the default Entity Framework initializer – which is to create the database if it doesn’t already exist. However, our database did already exist! This is because there is a new feature of Entity Framework 5 where Code First will add tables to an existing database as long as the target database doesn’t contain any of the tables from the model. At this point, it’s time to enable Migrations. We’ll open the Package Manger Console and execute the command: PM> Enable-Migrations -EnableAutomaticMigrations This will enable automatic migrations for our project. Because we used the "-EnableAutomaticMigrations” switch, it will create our Configuration class with a constructor that sets the AutomaticMigrationsEnabled property set to true: 1: public Configuration() 2: { 3: AutomaticMigrationsEnabled = true; 4: } We’ll now add our initial migration: PM> Add-Migration Initial This will create a migration class call “Initial” that contains the entire model. But we need to remove all of this code because our database already exists so we are just left with empty Up() and Down() methods. 1: public partial class Initial : DbMigration 2: { 3: public override void Up() 4: { 5: } 6: 7: public override void Down() 8: { 9: } 10: } If we don’t remove this code, we’ll get an exception the first time we attempt to run migrations that tells us: “There is already an object named 'UserProfile' in the database”. This blog post by Julie Lerman fully describes this scenario (i.e., enabling migrations on an existing database). Our next step is to add the Entity Framework initializer that will automatically use Migrations to update the database to the latest version. We will add these 2 lines of code to the Application_Start of the Global.asax: 1: Database.SetInitializer(new MigrateDatabaseToLatestVersion<UsersContext, Configuration>()); 2: new UsersContext().Database.Initialize(false); Note the Initialize() call will force the initializer to run if it has not been run before. At this point, we can publish again to make sure everything is still working as we are expecting. This time we’re going to specify in our publish profile that Code First Migrations should be executed:   Once we have re-published we can once again navigate to the Register page. At this point the database has not been changed but Migrations is now enabled on our SQL Database in Azure. We can now customize our model. Let’s add 2 new properties to the UserProfile class – Email and DateOfBirth: 1: [Table("UserProfile")] 2: public class UserProfile 3: { 4: [Key] 5: [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)] 6: public int UserId { get; set; } 7: public string UserName { get; set; } 8: public string Email { get; set; } 9: public DateTime DateOfBirth { get; set; } 10: } At this point all we need to do is simply re-publish. We’ll once again navigate to the Registration page and, because we had Automatic Migrations enabled, the database has been altered (*not* recreated) to add our 2 new columns. We can verify this by once again looking at SQL Management Studio:   Automatic Migrations provide a quick and easy way to keep your database in sync with your model without the worry of having to re-create your entire database and lose data. With Azure Web Sites you can set up automatic deployment with Git or TFS and automate the entire process to make it dead simple.

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• Windows Phone 7: Building a simple dictionary web client

  - by TechTwaddle

  Like I mentioned in this post a while back, I came across a dictionary web service called Aonaware that serves up word definitions from various dictionaries and is really easy to use. The services page on their website, http://services.aonaware.com/DictService/DictService.asmx, lists all the operations that are supported by the dictionary service. Here they are, Word Dictionary Web Service The following operations are supported. For a formal definition, please review the Service Description. Define Define given word, returning definitions from all dictionaries DefineInDict Define given word, returning definitions from specified dictionary DictionaryInfo Show information about the specified dictionary DictionaryList Returns a list of available dictionaries DictionaryListExtended Returns a list of advanced dictionaries (e.g. translating dictionaries) Match Look for matching words in all dictionaries using the given strategy MatchInDict Look for matching words in the specified dictionary using the given strategy ServerInfo Show remote server information StrategyList Return list of all available strategies on the server Follow the links above to get more information on each API. In this post we will be building a simple windows phone 7 client which uses this service to get word definitions for words entered by the user. The application will also allow the user to select a dictionary from all the available ones and look up the word definition in that dictionary. So of all the apis above we will be using only two, DictionaryList() to get a list of all supported dictionaries and DefineInDict() to get the word definition from a particular dictionary. Before we get started, a note to you all; I would have liked to implement this application using concepts from data binding, item templates, data templates etc. I have a basic understanding of what they are but, being a beginner, I am not very comfortable with those topics yet so I didn’t use them. I thought I’ll get this version out of the way and maybe in the next version I could give those a try. A somewhat scary mock-up of the what the final application will look like, Select Dictionary is a list picker control from the silverlight toolkit (you need to download and install the toolkit if you haven’t already). Below it is a textbox where the user can enter words to look up and a button beside it to fetch the word definition when clicked. Finally we have a textblock which occupies the remaining area and displays the word definition from the selected dictionary. Create a silverlight application for windows phone 7, AonawareDictionaryClient, and add references to the silverlight toolkit and the web service. From the solution explorer right on References and select Microsoft.Phone.Controls.Toolkit from under the .NET tab, Next, add a reference to the web service. Again right click on References and this time select Add Service Reference In the resulting dialog paste the service url in the Address field and press go, (url –> http://services.aonaware.com/DictService/DictService.asmx) once the service is discovered, provide a name for the NameSpace, in this case I’ve called it AonawareDictionaryService. Press OK. You can now use the classes and functions that are generated in the AonawareDictionaryClient.AonawareDictionaryService namespace. Let’s get the UI done now. In MainPage.xaml add a namespace declaration to use the toolkit controls, xmlns:toolkit="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls.Toolkit" the content of LayoutRoot is changed as follows, (sorry, no syntax highlighting in this post) <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,5,0,5">     <TextBlock x:Name="ApplicationTitle" Text="AONAWARE DICTIONARY CLIENT" Style="{StaticResource PhoneTextNormalStyle}"/>     <!--<TextBlock x:Name="PageTitle" Text="page name" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>--> </StackPanel> <!--ContentPanel - place additional content here--> <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">     <Grid.RowDefinitions>         <RowDefinition Height="Auto"/>         <RowDefinition Height="Auto"/>         <RowDefinition Height="*"/>     </Grid.RowDefinitions>     <toolkit:ListPicker Grid.Column="1" x:Name="listPickerDictionaryList"                         Header="Select Dictionary :">     </toolkit:ListPicker>     <Grid Grid.Row="1" Margin="0,5,0,0">         <Grid.ColumnDefinitions>             <ColumnDefinition Width="*"/>             <ColumnDefinition Width="Auto" />         </Grid.ColumnDefinitions>         <TextBox x:Name="txtboxInputWord" Grid.Column="0" GotFocus="OnTextboxInputWordGotFocus" />         <Button x:Name="btnGo" Grid.Column="1" Click="OnButtonGoClick" >             <Button.Content>                 <Image Source="/images/button-go.png"/>             </Button.Content>         </Button>     </Grid>     <ScrollViewer Grid.Row="2" x:Name="scrollViewer">         <TextBlock  Margin="12,5,12,5"  x:Name="txtBlockWordMeaning" HorizontalAlignment="Stretch"                    VerticalAlignment="Stretch" TextWrapping="Wrap"                    FontSize="26" />     </ScrollViewer> </Grid> I have commented out the PageTitle as it occupies too much valuable space, and the ContentPanel is changed to contain three rows. First row contains the list picker control, second row contains the textbox and the button, and the third row contains a textblock within a scroll viewer. The designer will now be showing the final ui, Now go to MainPage.xaml.cs, and add the following namespace declarations, using Microsoft.Phone.Controls; using AonawareDictionaryClient.AonawareDictionaryService; using System.IO.IsolatedStorage; A class called DictServiceSoapClient would have been created for you in the background when you added a reference to the web service. This class functions as a wrapper to the services exported by the web service. All the web service functions that we saw at the start can be access through this class, or more precisely through an object of this class. Create a data member of type DictServiceSoapClient in the Mainpage class, and a function which initializes it, DictServiceSoapClient DictSvcClient = null; private DictServiceSoapClient GetDictServiceSoapClient() {     if (null == DictSvcClient)     {         DictSvcClient = new DictServiceSoapClient();     }     return DictSvcClient; } We have two major tasks remaining. First, when the application loads we need to populate the list picker with all the supported dictionaries and second, when the user enters a word and clicks on the arrow button we need to fetch the word’s meaning. Populating the List Picker In the OnNavigatingTo event of the MainPage, we call the DictionaryList() api. This can also be done in the OnLoading event handler of the MainPage; not sure if one has an advantage over the other. Here’s the code for OnNavigatedTo, protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e) {     DictServiceSoapClient client = GetDictServiceSoapClient();     client.DictionaryListCompleted += new EventHandler<DictionaryListCompletedEventArgs>(OnGetDictionaryListCompleted);     client.DictionaryListAsync();     base.OnNavigatedTo(e); } Windows Phone 7 supports only async calls to web services. When we added a reference to the dictionary service, asynchronous versions of all the functions were generated automatically. So in the above function we register a handler to the DictionaryListCompleted event which will occur when the call to DictionaryList() gets a response from the server. Then we call the DictionaryListAsynch() function which is the async version of the DictionaryList() api. The result of this api will be sent to the handler OnGetDictionaryListCompleted(), void OnGetDictionaryListCompleted(object sender, DictionaryListCompletedEventArgs e) {     IsolatedStorageSettings settings = IsolatedStorageSettings.ApplicationSettings;     Dictionary[] listOfDictionaries;     if (e.Error == null)     {         listOfDictionaries = e.Result;         PopulateListPicker(listOfDictionaries, settings);     }     else if (settings.Contains("SavedDictionaryList"))     {         listOfDictionaries = settings["SavedDictionaryList"] as Dictionary[];         PopulateListPicker(listOfDictionaries, settings);     }     else     {         MessageBoxResult res = MessageBox.Show("An error occured while retrieving dictionary list, do you want to try again?", "Error", MessageBoxButton.OKCancel);         if (MessageBoxResult.OK == res)         {             GetDictServiceSoapClient().DictionaryListAsync();         }     }     settings.Save(); } I have used IsolatedStorageSettings to store a few things; the entire dictionary list and the dictionary that is selected when the user exits the application, so that the next time when the user starts the application the current dictionary is set to the last selected value. First we check if the api returned any error, if the error object is null e.Result will contain the list (actually array) of Dictionary type objects. If there was an error, we check the isolated storage settings to see if there is a dictionary list stored from a previous instance of the application and if so, we populate the list picker based on this saved list. Note that in this case there are chances that the dictionary list might be out of date if there have been changes on the server. Finally, if none of these cases are true, we display an error message to the user and try to fetch the list again. PopulateListPicker() is passed the array of Dictionary objects and the settings object as well, void PopulateListPicker(Dictionary[] listOfDictionaries, IsolatedStorageSettings settings) {     listPickerDictionaryList.Items.Clear();     foreach (Dictionary dictionary in listOfDictionaries)     {         listPickerDictionaryList.Items.Add(dictionary.Name);     }     settings["SavedDictionaryList"] = listOfDictionaries;     string savedDictionaryName;     if (settings.Contains("SavedDictionary"))     {         savedDictionaryName = settings["SavedDictionary"] as string;     }     else     {         savedDictionaryName = "WordNet (r) 2.0"; //default dictionary, wordnet     }     foreach (string dictName in listPickerDictionaryList.Items)     {         if (dictName == savedDictionaryName)         {             listPickerDictionaryList.SelectedItem = dictName;             break;         }     }     settings["SavedDictionary"] = listPickerDictionaryList.SelectedItem as string; } We first clear all the items from the list picker, add the dictionary names from the array and then create a key in the settings called SavedDictionaryList and store the dictionary list in it. We then check if there is saved dictionary available from a previous instance, if there is, we set it as the selected item in the list picker. And if not, we set “WordNet ® 2.0” as the default dictionary. Before returning, we save the selected dictionary in the “SavedDictionary” key of the isolated storage settings. Fetching word definitions Getting this part done is very similar to the above code. We get the input word from the textbox, call into DefineInDictAsync() to fetch the definition and when DefineInDictAsync completes, we get the result and display it in the textblock. Here is the handler for the button click, private void OnButtonGoClick(object sender, RoutedEventArgs e) {     txtBlockWordMeaning.Text = "Please wait..";     IsolatedStorageSettings settings = IsolatedStorageSettings.ApplicationSettings;     if (txtboxInputWord.Text.Trim().Length <= 0)     {         MessageBox.Show("Please enter a word in the textbox and press 'Go'");     }     else     {         Dictionary[] listOfDictionaries = settings["SavedDictionaryList"] as Dictionary[];         string selectedDictionary = listPickerDictionaryList.SelectedItem.ToString();         string dictId = "wn"; //default dictionary is wordnet (wn is the dict id)         foreach (Dictionary dict in listOfDictionaries)         {             if (dict.Name == selectedDictionary)             {                 dictId = dict.Id;                 break;             }         }         DictServiceSoapClient client = GetDictServiceSoapClient();         client.DefineInDictCompleted += new EventHandler<DefineInDictCompletedEventArgs>(OnDefineInDictCompleted);         client.DefineInDictAsync(dictId, txtboxInputWord.Text.Trim());     } } We validate the input and then select the dictionary id based on the currently selected dictionary. We need the dictionary id because the api DefineInDict() expects the dictionary identifier and not the dictionary name. We could very well have stored the dictionary id in isolated storage settings too. Again, same as before, we register a event handler for the DefineInDictCompleted event and call the DefineInDictAsync() method passing in the dictionary id and the input word. void OnDefineInDictCompleted(object sender, DefineInDictCompletedEventArgs e) {     WordDefinition wd = e.Result;     scrollViewer.ScrollToVerticalOffset(0.0f);     if (wd.Definitions.Length == 0)     {         txtBlockWordMeaning.Text = String.Format("No definitions were found for '{0}' in '{1}'", txtboxInputWord.Text.Trim(), listPickerDictionaryList.SelectedItem.ToString().Trim());     }     else     {         foreach (Definition def in wd.Definitions)         {             string str = def.WordDefinition;             str = str.Replace("  ", " "); //some formatting             txtBlockWordMeaning.Text = str;         }     } } When the api completes, e.Result will contain a WordDefnition object. This class is also generated in the background while adding the service reference. We check the word definitions within this class to see if any results were returned, if not, we display a message to the user in the textblock. If a definition was found the text on the textblock is set to display the definition of the word. Adding final touches, we now need to save the current dictionary when the application exits. A small but useful thing is selecting the entire word in the input textbox when the user selects it. This makes sure that if the user has looked up a definition for a really long word, he doesn’t have to press ‘clear’ too many times to enter the next word, protected override void OnNavigatingFrom(System.Windows.Navigation.NavigatingCancelEventArgs e) {     IsolatedStorageSettings settings = IsolatedStorageSettings.ApplicationSettings;     settings["SavedDictionary"] = listPickerDictionaryList.SelectedItem as string;     settings.Save();     base.OnNavigatingFrom(e); } private void OnTextboxInputWordGotFocus(object sender, RoutedEventArgs e) {     TextBox txtbox = sender as TextBox;     if (txtbox.Text.Trim().Length > 0)     {         txtbox.SelectionStart = 0;         txtbox.SelectionLength = txtbox.Text.Length;     } } OnNavigatingFrom() is called whenever you navigate away from the MainPage, since our application contains only one page that would mean that it is exiting. I leave you with a short video of the application in action, but before that if you have any suggestions on how to make the code better and improve it please do leave a comment. Until next time…

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• Trabajando el redireccionamiento de usuarios/Working with user redirect methods

  - by Jason Ulloa

  La protección de las aplicaciones es un elemento que no se puede dejar por fuera cuando se elabora un sistema. Cada parte o elemento de código que protege nuetra aplicación debe ser cuidadosamente seleccionado y elaborado. Una de las cosas comunes con las que nos topamos en asp.net cuando deseamos trabajar con usuarios, es con la necesidad de poder redireccionarlos a los distintos elementos o páginas dependiendo del rol. Pues precisamente eso es lo que haremos, vamos a trabajar con el Web.config de nuestra aplicación y le añadiremos unas pequeñas líneas de código para lograr dar un poco mas de seguridad al sistema y sobre todo lograr el redireccionamiento. Así que veamos como logramos lo deseado: Como bien sabemos el web.config nos permite manejar muchos elementos dentro de asp.net, muchos de ellos relacionados con la seguridad, asi como tambien nos brinda la posibilidad de poder personalizar los elementos para poder adaptarlo a nuestras necesidades. Así que, basandonos en el principio de que podemos personalizar el web.config, entonces crearemos una sección personalizada, que será la que utilicemos para manejar el redireccionamiento: Nuestro primer paso será ir a nuestro web.config y buscamos las siguientes líneas: <configuration>     <configSections>  </sectionGroup>             </sectionGroup>         </sectionGroup> Y luego de ellas definiremos una nueva sección  <section name="loginRedirectByRole" type="crabit.LoginRedirectByRoleSection" allowLocation="true" allowDefinition="Everywhere" /> El section name corresponde al nombre de nuestra nueva sección Type corresponde al nombre de la clase (que pronto realizaremos) y que será la encargada del Redirect Como estamos trabajando dentro de la seccion de configuración una vez definidad nuestra sección personalizada debemos cerrar esta sección  </configSections> Por lo que nuestro web.config debería lucir de la siguiente forma <configuration>     <configSections>  </sectionGroup>             </sectionGroup>         </sectionGroup> <section name="loginRedirectByRole" type="crabit.LoginRedirectByRoleSection" allowLocation="true" allowDefinition="Everywhere" /> </configSections> Anteriormente definimos nuestra sección, pero esta sería totalmente inútil sin el Metodo que le da vida. En nuestro caso el metodo loginRedirectByRole, este metodo lo definiremos luego del </configSections> último que cerramos: <loginRedirectByRole>     <roleRedirects>       <add role="Administrador" url="~/Admin/Default.aspx" />       <add role="User" url="~/User/Default.aspx" />     </roleRedirects>   </loginRedirectByRole> Como vemos, dentro de nuestro metodo LoginRedirectByRole tenemos el elemento add role. Este elemento será el que posteriormente le indicará a la aplicación hacia donde irá el usuario cuando realice un login correcto. Así que, veamos un poco esta configuración: add role="Administrador" corresponde al nombre del Role que tenemos definidio, pueden existir tantos elementos add role como tengamos definidos en nuestra aplicación. El elemento URL indica la ruta o página a la que será dirigido un usuario una vez logueado y dentro de la aplicación. Como vemos estamos utilizando el ~ para indicar que es una ruta relativa. Con esto hemos terminado la configuración de nuestro web.config, ahora veamos a fondo el código que se encargará de leer estos elementos y de utilziarlos: Para nuestro ejemplo, crearemos una nueva clase denominada LoginRedirectByRoleSection, recordemos que esta clase es la que llamamos en el elemento TYPE definido en la sección de nuestro web.config. Una vez creada la clase, definiremos algunas propiedades, pero antes de ello le indicaremos a nuestra clase que debe heredar de configurationSection, esto para poder obtener los elementos del web.config.  Inherits ConfigurationSection Ahora nuestra primer propiedad   <ConfigurationProperty("roleRedirects")> _         Public Property RoleRedirects() As RoleRedirectCollection             Get                 Return DirectCast(Me("roleRedirects"), RoleRedirectCollection)             End Get             Set(ByVal value As RoleRedirectCollection)                 Me("roleRedirects") = value             End Set         End Property     End Class Esta propiedad será la encargada de obtener todos los roles que definimos en la metodo personalizado de nuestro web.config Nuestro segundo paso será crear una segunda clase (en la misma clase LoginRedirectByRoleSection) a esta clase la llamaremos RoleRedirectCollection y la heredaremos de ConfigurationElementCollection y definiremos lo siguiente Public Class RoleRedirectCollection         Inherits ConfigurationElementCollection         Default Public ReadOnly Property Item(ByVal index As Integer) As RoleRedirect             Get                 Return DirectCast(BaseGet(index), RoleRedirect)             End Get         End Property         Default Public ReadOnly Property Item(ByVal key As Object) As RoleRedirect             Get                 Return DirectCast(BaseGet(key), RoleRedirect)             End Get         End Property         Protected Overrides Function CreateNewElement() As ConfigurationElement             Return New RoleRedirect()         End Function         Protected Overrides Function GetElementKey(ByVal element As ConfigurationElement) As Object             Return DirectCast(element, RoleRedirect).Role         End Function     End Class Nuevamente crearemos otra clase esta vez llamada RoleRedirect y en este caso la heredaremos de ConfigurationElement. Nuestra nueva clase debería lucir así: Public Class RoleRedirect         Inherits ConfigurationElement         <ConfigurationProperty("role", IsRequired:=True)> _         Public Property Role() As String             Get                 Return DirectCast(Me("role"), String)             End Get             Set(ByVal value As String)                 Me("role") = value             End Set         End Property         <ConfigurationProperty("url", IsRequired:=True)> _         Public Property Url() As String             Get                 Return DirectCast(Me("url"), String)             End Get             Set(ByVal value As String)                 Me("url") = value             End Set         End Property     End Class Una vez que nuestra clase madre esta lista, lo unico que nos queda es un poc de codigo en la pagina de login de nuestro sistema (por supuesto, asumo que estan utilizando  los controles de login que por defecto tiene asp.net). Acá definiremos nuestros dos últimos metodos  Protected Sub ctllogin_LoggedIn(ByVal sender As Object, ByVal e As System.EventArgs) Handles ctllogin.LoggedIn         RedirectLogin(ctllogin.UserName)     End Sub El procedimiento loggeding es parte del control login de asp.net y se desencadena en el momento en que el usuario hace loguin correctametne en nuestra aplicación Este evento desencadenará el siguiente procedimiento para redireccionar.     Private Sub RedirectLogin(ByVal username As String)         Dim roleRedirectSection As crabit.LoginRedirectByRoleSection = DirectCast(ConfigurationManager.GetSection("loginRedirectByRole"), crabit.LoginRedirectByRoleSection)         For Each roleRedirect As crabit.RoleRedirect In roleRedirectSection.RoleRedirects             If Roles.IsUserInRole(username, roleRedirect.Role) Then                 Response.Redirect(roleRedirect.Url)             End If         Next     End Sub   Con esto, nuestra aplicación debería ser capaz de redireccionar sin problemas y manejar los roles.  Además, tambien recordar que nuestro ejemplo se basa en la utilización del esquema de bases de datos que por defecto nos proporcionada asp.net.

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• What is the most efficient way to convert to binary and back in C#?

  - by Saad Imran.

  I'm trying to write a general purpose socket server for a game I'm working on. I know I could very well use already built servers like SmartFox and Photon, but I wan't to go through the pain of creating one myself for learning purposes. I've come up with a BSON inspired protocol to convert the the basic data types, their arrays, and a special GSObject to binary and arrange them in a way so that it can be put back together into object form on the client end. At the core, the conversion methods utilize the .Net BitConverter class to convert the basic data types to binary. Anyways, the problem is performance, if I loop 50,000 times and convert my GSObject to binary each time it takes about 5500ms (the resulting byte[] is just 192 bytes per conversion). I think think this would be way too slow for an MMO that sends 5-10 position updates per second with a 1000 concurrent users. Yes, I know it's unlikely that a game will have a 1000 users on at the same time, but like I said earlier this is supposed to be a learning process for me, I want to go out of my way and build something that scales well and can handle at least a few thousand users. So yea, if anyone's aware of other conversion techniques or sees where I'm loosing performance I would appreciate the help. GSBitConverter.cs This is the main conversion class, it adds extension methods to main datatypes to convert to the binary format. It uses the BitConverter class to convert the base types. I've shown only the code to convert integer and integer arrays, but the rest of the method are pretty much replicas of those two, they just overload the type. public static class GSBitConverter { public static byte[] ToGSBinary(this short value) { return BitConverter.GetBytes(value); } public static byte[] ToGSBinary(this IEnumerable<short> value) { List<byte> bytes = new List<byte>(); short length = (short)value.Count(); bytes.AddRange(length.ToGSBinary()); for (int i = 0; i < length; i++) bytes.AddRange(value.ElementAt(i).ToGSBinary()); return bytes.ToArray(); } public static byte[] ToGSBinary(this bool value); public static byte[] ToGSBinary(this IEnumerable<bool> value); public static byte[] ToGSBinary(this IEnumerable<byte> value); public static byte[] ToGSBinary(this int value); public static byte[] ToGSBinary(this IEnumerable<int> value); public static byte[] ToGSBinary(this long value); public static byte[] ToGSBinary(this IEnumerable<long> value); public static byte[] ToGSBinary(this float value); public static byte[] ToGSBinary(this IEnumerable<float> value); public static byte[] ToGSBinary(this double value); public static byte[] ToGSBinary(this IEnumerable<double> value); public static byte[] ToGSBinary(this string value); public static byte[] ToGSBinary(this IEnumerable<string> value); public static string GetHexDump(this IEnumerable<byte> value); } Program.cs Here's the the object that I'm converting to binary in a loop. class Program { static void Main(string[] args) { GSObject obj = new GSObject(); obj.AttachShort("smallInt", 15); obj.AttachInt("medInt", 120700); obj.AttachLong("bigInt", 10900800700); obj.AttachDouble("doubleVal", Math.PI); obj.AttachStringArray("muppetNames", new string[] { "Kermit", "Fozzy", "Piggy", "Animal", "Gonzo" }); GSObject apple = new GSObject(); apple.AttachString("name", "Apple"); apple.AttachString("color", "red"); apple.AttachBool("inStock", true); apple.AttachFloat("price", (float)1.5); GSObject lemon = new GSObject(); apple.AttachString("name", "Lemon"); apple.AttachString("color", "yellow"); apple.AttachBool("inStock", false); apple.AttachFloat("price", (float)0.8); GSObject apricoat = new GSObject(); apple.AttachString("name", "Apricoat"); apple.AttachString("color", "orange"); apple.AttachBool("inStock", true); apple.AttachFloat("price", (float)1.9); GSObject kiwi = new GSObject(); apple.AttachString("name", "Kiwi"); apple.AttachString("color", "green"); apple.AttachBool("inStock", true); apple.AttachFloat("price", (float)2.3); GSArray fruits = new GSArray(); fruits.AddGSObject(apple); fruits.AddGSObject(lemon); fruits.AddGSObject(apricoat); fruits.AddGSObject(kiwi); obj.AttachGSArray("fruits", fruits); Stopwatch w1 = Stopwatch.StartNew(); for (int i = 0; i < 50000; i++) { byte[] b = obj.ToGSBinary(); } w1.Stop(); Console.WriteLine(BitConverter.IsLittleEndian ? "Little Endian" : "Big Endian"); Console.WriteLine(w1.ElapsedMilliseconds + "ms"); } Here's the code for some of my other classes that are used in the code above. Most of it is repetitive. GSObject GSArray GSWrappedObject

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• MVVM Light V4 preview 2 (BL0015) #mvvmlight

  - by Laurent Bugnion

  Over the past few weeks, I have worked hard on a few new features for MVVM Light V4. Here is a second early preview (consider this pre-alpha if you wish). The features are unit-tested, but I am now looking for feedback and there might be bugs! Bug correction: Messenger.CleanupList is now thread safe This was an annoying bug that is now corrected: In some circumstances, an exception could be thrown when the Messenger’s recipients list was cleaned up (i.e. the “dead” instances were removed). The method is called now and then and the exception was thrown apparently at random. In fact it was really a multi-threading issue, which is now corrected. Bug correction: AllowPartiallyTrustedCallers prevents EventToCommand to work This is a particularly annoying regression bug that was introduced in BL0014. In order to allow MVVM Light to work in XBAPs too, I added the AllowPartiallyTrustedCallers attribute to the assemblies. However, we just found out that this causes issues when using EventToCommand. In order to allow EventToCommand to continue working, I reverted to the previous state by removing the AllowPartiallyTrustedCallers attribute for now. I will work with my friends at Microsoft to try and find a solution. Stay tuned. Bug correction: XML documentation file is now generated in Release configuration The XML documentation file was not generated for the Release configuration. This was a simple flag in the project file that I had forgotten to set. This is corrected now. Applying EventToCommand to non-FrameworkElements This feature has been requested in order to be able to execute a command when a Storyboard is completed. I implemented this, but unfortunately found out that EventToCommand can only be added to Storyboards in Silverlight 3 and Silverlight 4, but not in WPF or in Windows Phone 7. This obviously limits the usefulness of this change, but I decided to publish it anyway, because it is pretty damn useful in Silverlight… Why not in WPF? In WPF, Storyboards added to a resource dictionary are frozen. This is a feature of WPF which allows to optimize certain objects for performance: By freezing them, it is a contract where we say “this object will not be modified anymore, so do your perf optimization on them without worrying too much”. Unfortunately, adding a Trigger (such as EventTrigger) to an object in resources does not work if this object is frozen… and unfortunately, there is no way to tell WPF not to freeze the Storyboard in the resources… so there is no way around that (at least none I can see. In Silverlight, objects are not frozen, so an EventTrigger can be added without problems. Why not in WP7? In Windows Phone 7, there is a totally different issue: Adding a Trigger can only be done to a FrameworkElement, which Storyboard is not. Here I think that we might see a change in a future version of the framework, so maybe this small trick will work in the future. Workaround? Since you cannot use the EventToCommand on a Storyboard in WPF and in WP7, the workaround is pretty obvious: Handle the Completed event in the code behind, and call the Command from there on the ViewModel. This object can be obtained by casting the DataContext to the ViewModel type. This means that the View needs to know about the ViewModel, but I never had issues with that anyway. New class: NotifyPropertyChanged Sometimes when you implement a model object (for example Customer), you would like to have it implement INotifyPropertyChanged, but without having all the frills of a ViewModelBase. A new class named NotifyPropertyChanged allows you to do that. This class is a simple implementation of INotifyPropertyChaned (with all the overloads of RaisePropertyChanged that were implemented in BL0014). In fact, ViewModelBase inherits NotifyPropertyChanged. ViewModelBase does not implement IDisposable anymore The IDisposable interface and the Dispose method had been marked obsolete in the ViewModelBase class already in V3. Now they have been removed. Note: By this, I do not mean that IDisposable is a bad interface, or that it shouldn’t be used on viewmodels. In the contrary, I know that this interface is very useful in certain circumstances. However, I think that having it by default on every instance of ViewModelBase was sending a wrong message. This interface has a strong meaning in .NET: After Dispose has been executed, the instance should not be used anymore, and should be ready for garbage collection. What I really wanted to have on ViewModelBase was rather a simple cleanup method, something that can be executed now and then during runtime. This is fulfilled by the ICleanup interface and its Cleanup method. If your ViewModels need IDisposable, you can still use it! You will just have to implement the interface on the class itself, because it is not available on ViewModelBase anymore. What’s next? I have a couple exciting new features implemented already but that need more testing before they go live… Just stay tuned and by MIX11 (12-14 April 2011), we should see at least a major addition to MVVM Light Toolkit, as well as another smaller feature which is pretty cool nonetheless More about this later! Happy Coding Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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• The case of the phantom ADF developer (and other yarns)

  - by Chris Muir

  A few years of ADF experience means I see common mistakes made by different developers, some I regularly make myself.  This post is designed to assist beginners to Oracle JDeveloper Application Development Framework (ADF) avoid a common ADF pitfall, the case of the phantom ADF developer [add Scooby-Doo music here]. ADF Business Components - triggers, default table values and instead of views. Oracle's JDeveloper tutorials help with the A-B-Cs of ADF development, typically built on the nice 'n safe demo schema provided by with the Oracle database such as the HR demo schema. However it's not too long until ADF beginners, having built up some confidence from learning with the tutorials and vanilla demo schemas, start building ADF Business Components based upon their own existing database schema objects.  This is where unexpected problems can sneak in. The crime Developers may encounter a surprising error at runtime when editing a record they just created or updated and committed to the database, based on their own existing tables, namely the error: JBO-25014: Another user has changed the row with primary key oracle.jbo.Key[x] ...where X is the primary key value of the row at hand.  In a production environment with multiple users this error may be legit, one of the other users has updated the row since you queried it.  Yet in a development environment this error is just plain confusing.  If developers are isolated in their own database, creating and editing records they know other users can't possibly be working with, or all the other developers have gone home for the day, how is this error possible? There are no other users?  It must be the phantom ADF developer! [insert dramatic music here] The following picture is what you'll see in the Business Component Browser, and you'll receive a similar error message via an ADF Faces page: A false conclusion What can possibly cause this issue if it isn't our phantom ADF developer?  Doesn't ADF BC implement record locking, locking database records when the row is modified in the ADF middle-tier by a user?  How can our phantom ADF developer even take out a lock if this is the case?  Maybe ADF has a bug, maybe ADF isn't implementing record locking at all?  Shouldn't we see the error "JBO-26030: Failed to lock the record, another user holds the lock" as we attempt to modify the record, why do we see JBO-25014? : Let's verify that ADF is in fact issuing the correct SQL LOCK-FOR-UPDATE statement to the database. First we need to verify ADF's locking strategy.  It is determined by the Application Module's jbo.locking.mode property.  The default (as of JDev 11.1.1.4.0 if memory serves me correct) and recommended value is optimistic, and the other valid value is pessimistic. Next we need a mechanism to check that ADF is issuing the LOCK statements to the database.  We could ask DBAs to monitor locks with OEM, but optimally we'd rather not involve overworked DBAs in this process, so instead we can use the ADF runtime setting –Djbo.debugoutput=console.  At runtime this options turns on instrumentation within the ADF BC layer, which among a lot of extra detail displayed in the log window, will show the actual SQL statement issued to the database, including the LOCK statement we're looking to confirm. Setting our locking mode to pessimistic, opening the Business Components Browser of a JSF page allowing us to edit a record, say the CHARGEABLE field within a BOOKINGS record where BOOKING_NO = 1206, upon editing the record see among others the following log entries: [421] Built select: 'SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings'[422] Executing LOCK...SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings WHERE BOOKING_NO=:1 FOR UPDATE NOWAIT[423] Where binding param 1: 1206  As can be seen on line 422, in fact a LOCK-FOR-UPDATE is indeed issued to the database.  Later when we commit the record we see: [441] OracleSQLBuilder: SAVEPOINT 'BO_SP'[442] OracleSQLBuilder Executing, Lock 1 DML on: BOOKINGS (Update)[443] UPDATE buf Bookings>#u SQLStmtBufLen: 210, actual=62[444] UPDATE BOOKINGS Bookings SET CHARGEABLE=:1 WHERE BOOKING_NO=:2[445] Update binding param 1: N[446] Where binding param 2: 1206[447] BookingsView1 notify COMMIT ... [448] _LOCAL_VIEW_USAGE_model_Bookings_ResourceTypesView1 notify COMMIT ... [449] EntityCache close prepared statement ....and as a result the changes are saved to the database, and the lock is released. Let's see what happens when we use the optimistic locking mode, this time to change the same BOOKINGS record CHARGEABLE column again.  As soon as we edit the record we see little activity in the logs, nothing to indicate any SQL statement, let alone a LOCK has been taken out on the row. However when we save our records by issuing a commit, the following is recorded in the logs: [509] OracleSQLBuilder: SAVEPOINT 'BO_SP'[510] OracleSQLBuilder Executing doEntitySelect on: BOOKINGS (true)[511] Built select: 'SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings'[512] Executing LOCK...SELECT BOOKING_NO, EVENT_NO, RESOURCE_CODE, CHARGEABLE, MADE_BY, QUANTITY, COST, STATUS, COMMENTS FROM BOOKINGS Bookings WHERE BOOKING_NO=:1 FOR UPDATE NOWAIT[513] Where binding param 1: 1205[514] OracleSQLBuilder Executing, Lock 2 DML on: BOOKINGS (Update)[515] UPDATE buf Bookings>#u SQLStmtBufLen: 210, actual=62[516] UPDATE BOOKINGS Bookings SET CHARGEABLE=:1 WHERE BOOKING_NO=:2[517] Update binding param 1: Y[518] Where binding param 2: 1205[519] BookingsView1 notify COMMIT ... [520] _LOCAL_VIEW_USAGE_model_Bookings_ResourceTypesView1 notify COMMIT ... [521] EntityCache close prepared statement Again even though we're seeing the midtier delay the LOCK statement until commit time, it is in fact occurring on line 412, and released as part of the commit issued on line 419.  Therefore with either optimistic or pessimistic locking a lock is indeed issued. Our conclusion at this point must be, unless there's the unlikely cause the LOCK statement is never really hitting the database, or the even less likely cause the database has a bug, then ADF does in fact take out a lock on the record before allowing the current user to update it.  So there's no way our phantom ADF developer could even modify the record if he tried without at least someone receiving a lock error. Hmm, we can only conclude the locking mode is a red herring and not the true cause of our problem.  Who is the phantom? At this point we'll need to conclude that the error message "JBO-25014: Another user has changed" is somehow legit, even though we don't understand yet what's causing it. This leads onto two further questions, how does ADF know another user has changed the row, and what's been changed anyway? To answer the first question, how does ADF know another user has changed the row, the Fusion Guide's section 4.10.11 How to Protect Against Losing Simultaneous Updated Data , that details the Entity Object Change-Indicator property, gives us the answer: At runtime the framework provides automatic "lost update" detection for entity objects to ensure that a user cannot unknowingly modify data that another user has updated and committed in the meantime. Typically, this check is performed by comparing the original values of each persistent entity attribute against the corresponding current column values in the database at the time the underlying row is locked. Before updating a row, the entity object verifies that the row to be updated is still consistent with the current state of the database.  The guide further suggests to make this solution more efficient: You can make the lost update detection more efficient by identifying any attributes of your entity whose values you know will be updated whenever the entity is modified. Typical candidates include a version number column or an updated date column in the row.....To detect whether the row has been modified since the user queried it in the most efficient way, select the Change Indicator option to compare only the change-indicator attribute values. We now know that ADF BC doesn't use the locking mechanism at all to protect the current user against updates, but rather it keeps a copy of the original record fetched, separate to the user changed version of the record, and it compares the original record against the one in the database when the lock is taken out.  If values don't match, be it the default compare-all-columns behaviour, or the more efficient Change Indicator mechanism, ADF BC will throw the JBO-25014 error. This leaves one last question.  Now we know the mechanism under which ADF identifies a changed row, what we don't know is what's changed and who changed it? The real culprit What's changed?  We know the record in the mid-tier has been changed by the user, however ADF doesn't use the changed record in the mid-tier to compare to the database record, but rather a copy of the original record before it was changed.  This leaves us to conclude the database record has changed, but how and by who? There are three potential causes: Database triggers The database trigger among other uses, can be configured to fire PLSQL code on a database table insert, update or delete.  In particular in an insert or update the trigger can override the value assigned to a particular column.  The trigger execution is actioned by the database on behalf of the user initiating the insert or update action. Why this causes the issue specific to our ADF use, is when we insert or update a record in the database via ADF, ADF keeps a copy of the record written to the database.  However the cached record is instantly out of date as the database triggers have modified the record that was actually written to the database.  Thus when we update the record we just inserted or updated for a second time to the database, ADF compares its original copy of the record to that in the database, and it detects the record has been changed – giving us JBO-25014. This is probably the most common cause of this problem. Default values A second reason this issue can occur is another database feature, default column values.  When creating a database table the schema designer can define default values for specific columns.  For example a CREATED_BY column could be set to SYSDATE, or a flag column to Y or N.  Default values are only used by the database when a user inserts a new record and the specific column is assigned NULL.  The database in this case will overwrite the column with the default value. As per the database trigger section, it then becomes apparent why ADF chokes on this feature, though it can only specifically occur in an insert-commit-update-commit scenario, not the update-commit-update-commit scenario. Instead of trigger views I must admit I haven't double checked this scenario but it seems plausible, that of the Oracle database's instead of trigger view (sometimes referred to as instead of views).  A view in the database is based on a query, and dependent on the queries complexity, may support insert, update and delete functionality to a limited degree.  In order to support fully insertable, updateable and deletable views, Oracle introduced the instead of view, that gives the view designer the ability to not only define the view query, but a set of programmatic PLSQL triggers where the developer can define their own logic for inserts, updates and deletes. While this provides the database programmer a very powerful feature, it can cause issues for our ADF application.  On inserting or updating a record in the instead of view, the record and it's data that goes in is not necessarily the data that comes out when ADF compares the records, as the view developer has the option to practically do anything with the incoming data, including throwing it away or pushing it to tables which aren't used by the view underlying query for fetching the data. Readers are at this point reminded that this article is specifically about how the JBO-25014 error occurs in the context of 1 developer on an isolated database.  The article is not considering how the error occurs in a production environment where there are multiple users who can cause this error in a legitimate fashion.  Assuming none of the above features are the cause of the problem, and optimistic locking is turned on (this error is not possible if pessimistic locking is the default mode *and* none of the previous causes are possible), JBO-25014 is quite feasible in a production ADF application if 2 users modify the same record. At this point under project timelines pressure, the obvious fix for developers is to drop both database triggers and default values from the underlying tables.  However we must be careful that these legacy constructs aren't used and assumed to be in place by other legacy systems.  Dropping the database triggers or default value that the existing Oracle Forms  applications assumes and requires to be in place could cause unexpected behaviour and bugs in the Forms application.  Proficient software engineers would recognize such a change may require a partial or full regression test of the existing legacy system, a potentially costly and timely exercise, not ideal. Solving the mystery once and for all Luckily ADF has built in functionality to deal with this issue, though it's not a surprise, as Oracle as the author of ADF also built the database, and are fully aware of the Oracle database's feature set.  At the Entity Object attribute level, the Refresh After Insert and Refresh After Update properties.  Simply selecting these instructs ADF BC after inserting or updating a record to the database, to expect the database to modify the said attributes, and read a copy of the changed attributes back into its cached mid-tier record.  Thus next time the developer modifies the current record, the comparison between the mid-tier record and the database record match, and JBO-25014: Another user has changed" is no longer an issue. [Post edit - as per the comment from Oracle's Steven Davelaar below, as he correctly points out the above solution will not work for instead-of-triggers views as it relies on SQL RETURNING clause which is incompatible with this type of view] Alternatively you can set the Change Indicator on one of the attributes.  This will work as long as the relating column for the attribute in the database itself isn't inadvertently updated.  In turn you're possibly just masking the issue rather than solving it, because if another developer turns the Change Indicator back on the original issue will return.

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• Implementing an Interceptor Using NHibernate’s Built In Dynamic Proxy Generator

  - by Ricardo Peres

  NHibernate 3.2 came with an included proxy generator, which means there is no longer the need – or the possibility, for that matter – to choose Castle DynamicProxy, LinFu or Spring. This is actually a good thing, because it means one less assembly to deploy. Apparently, this generator was based, at least partially, on LinFu. As there are not many tutorials out there demonstrating it’s usage, here’s one, for demonstrating one of the most requested features: implementing INotifyPropertyChanged. This interceptor, of course, will still feature all of NHibernate’s functionalities that you are used to, such as lazy loading, and such. We will start by implementing an NHibernate interceptor, by inheriting from the base class NHibernate.EmptyInterceptor. This class does not do anything by itself, but it allows us to plug in behavior by overriding some of its methods, in this case, Instantiate: 1: public class NotifyPropertyChangedInterceptor : EmptyInterceptor 2: { 3: private ISession session = null; 4:  5: private static readonly ProxyFactory factory = new ProxyFactory(); 6:  7: public override void SetSession(ISession session) 8: { 9: this.session = session; 10: base.SetSession(session); 11: } 12:  13: public override Object Instantiate(String clazz, EntityMode entityMode, Object id) 14: { 15: Type entityType = Type.GetType(clazz); 16: IProxy proxy = factory.CreateProxy(entityType, new _NotifyPropertyChangedInterceptor(), typeof(INotifyPropertyChanged)) as IProxy; 17: 18: _NotifyPropertyChangedInterceptor interceptor = proxy.Interceptor as _NotifyPropertyChangedInterceptor; 19: interceptor.Proxy = this.session.SessionFactory.GetClassMetadata(entityType).Instantiate(id, entityMode); 20:  21: this.session.SessionFactory.GetClassMetadata(entityType).SetIdentifier(proxy, id, entityMode); 22:  23: return (proxy); 24: } 25: } Then we need a class that implements the NHibernate dynamic proxy behavior, let’s place it inside our interceptor, because it will only need to be used there: 1: class _NotifyPropertyChangedInterceptor : NHibernate.Proxy.DynamicProxy.IInterceptor 2: { 3: private PropertyChangedEventHandler changed = delegate { }; 4:  5: public Object Proxy 6: { 7: get; 8: set;} 9:  10: #region IInterceptor Members 11:  12: public Object Intercept(InvocationInfo info) 13: { 14: Boolean isSetter = info.TargetMethod.Name.StartsWith("set_") == true; 15: Object result = null; 16:  17: if (info.TargetMethod.Name == "add_PropertyChanged") 18: { 19: PropertyChangedEventHandler propertyChangedEventHandler = info.Arguments[0] as PropertyChangedEventHandler; 20: this.changed += propertyChangedEventHandler; 21: } 22: else if (info.TargetMethod.Name == "remove_PropertyChanged") 23: { 24: PropertyChangedEventHandler propertyChangedEventHandler = info.Arguments[0] as PropertyChangedEventHandler; 25: this.changed -= propertyChangedEventHandler; 26: } 27: else 28: { 29: result = info.TargetMethod.Invoke(this.Proxy, info.Arguments); 30: } 31:  32: if (isSetter == true) 33: { 34: String propertyName = info.TargetMethod.Name.Substring("set_".Length); 35: this.changed(this.Proxy, new PropertyChangedEventArgs(propertyName)); 36: } 37:  38: return (result); 39: } 40:  41: #endregion 42: } What this does for every interceptable method (those who are either virtual or from the INotifyPropertyChanged) is: For methods that came from the INotifyPropertyChanged interface, add_PropertyChanged and remove_PropertyChanged (yes, events are methods ), we add an implementation that adds or removes the event handlers to the delegate which we declared as changed; For all the others, we direct them to the place where they are actually implemented, which is the Proxy field; If the call is setting a property, it fires afterwards the PropertyChanged event. In order to use this, we need to add the interceptor to the Configuration before building the ISessionFactory: 1: using (ISessionFactory factory = cfg.SetInterceptor(new NotifyPropertyChangedInterceptor()).BuildSessionFactory()) 2: { 3: using (ISession session = factory.OpenSession()) 4: using (ITransaction tx = session.BeginTransaction()) 5: { 6: Customer customer = session.Get<Customer>(100); //some id 7: INotifyPropertyChanged inpc = customer as INotifyPropertyChanged; 8: inpc.PropertyChanged += delegate(Object sender, PropertyChangedEventArgs e) 9: { 10: //fired when a property changes 11: }; 12: customer.Address = "some other address"; //will raise PropertyChanged 13: customer.RecentOrders.ToList(); //will trigger the lazy loading 14: } 15: } Any problems, questions, do drop me a line!

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• Do Not Optimize Without Measuring

  - by Alois Kraus

  Recently I had to do some performance work which included reading a lot of code. It is fascinating with what ideas people come up to solve a problem. Especially when there is no problem. When you look at other peoples code you will not be able to tell if it is well performing or not by reading it. You need to execute it with some sort of tracing or even better under a profiler. The first rule of the performance club is not to think and then to optimize but to measure, think and then optimize. The second rule is to do this do this in a loop to prevent slipping in bad things for too long into your code base. If you skip for some reason the measure step and optimize directly it is like changing the wave function in quantum mechanics. This has no observable effect in our world since it does represent only a probability distribution of all possible values. In quantum mechanics you need to let the wave function collapse to a single value. A collapsed wave function has therefore not many but one distinct value. This is what we physicists call a measurement. If you optimize your application without measuring it you are just changing the probability distribution of your potential performance values. Which performance your application actually has is still unknown. You only know that it will be within a specific range with a certain probability. As usual there are unlikely values within your distribution like a startup time of 20 minutes which should only happen once in 100 000 years. 100 000 years are a very short time when the first customer tries your heavily distributed networking application to run over a slow WIFI network… What is the point of this? Every programmer/architect has a mental performance model in his head. A model has always a set of explicit preconditions and a lot more implicit assumptions baked into it. When the model is good it will help you to think of good designs but it can also be the source of problems. In real world systems not all assumptions of your performance model (implicit or explicit) hold true any longer. The only way to connect your performance model and the real world is to measure it. In the WIFI example the model did assume a low latency high bandwidth LAN connection. If this assumption becomes wrong the system did have a drastic change in startup time. Lets look at a example. Lets assume we want to cache some expensive UI resource like fonts objects. For this undertaking we do create a Cache class with the UI themes we want to support. Since Fonts are expensive objects we do create it on demand the first time the theme is requested. A simple example of a Theme cache might look like this: using System; using System.Collections.Generic; using System.Drawing; struct Theme { public Color Color; public Font Font; } static class ThemeCache { static Dictionary<string, Theme> _Cache = new Dictionary<string, Theme> { {"Default", new Theme { Color = Color.AliceBlue }}, {"Theme12", new Theme { Color = Color.Aqua }}, }; public static Theme Get(string theme) { Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } return cached; } } class Program { static void Main(string[] args) { Theme item = ThemeCache.Get("Theme12"); item = ThemeCache.Get("Theme12"); } } This cache does create font objects only once since on first retrieve of the Theme object the font is added to the Theme object. When we let the application run it should print “Creating new font” only once. Right? Wrong! The vigilant readers have spotted the issue already. The creator of this cache class wanted to get maximum performance. So he decided that the Theme object should be a value type (struct) to not put too much pressure on the garbage collector. The code Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } does work with a copy of the value stored in the dictionary. This means we do mutate a copy of the Theme object and return it to our caller. But the original Theme object in the dictionary will have always null for the Font field! The solution is to change the declaration of struct Theme to class Theme or to update the theme object in the dictionary. Our cache as it is currently is actually a non caching cache. The funny thing was that I found out with a profiler by looking at which objects where finalized. I found way too many font objects to be finalized. After a bit debugging I found the allocation source for Font objects was this cache. Since this cache was there for years it means that the cache was never needed since I found no perf issue due to the creation of font objects. the cache was never profiled if it did bring any performance gain. to make the cache beneficial it needs to be accessed much more often. That was the story of the non caching cache. Next time I will write something something about measuring.

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• Windows Workflow Foundation (WF) and things I wish were more intuitive

  - by pjohnson

  I've started using Windows Workflow Foundation, and so far ran into a few things that aren't incredibly obvious. Microsoft did a good job of providing a ton of samples, which is handy because you need them to get anywhere with WF. The docs are thin, so I've been bouncing between samples and downloadable labs to figure out how to implement various activities in a workflow. Code separation or not? You can create a workflow and activity in Visual Studio with or without code separation, i.e. just a .cs "Component" style object with a Designer.cs file, or a .xoml XML markup file with code behind (beside?) it. Absence any obvious advantage to one or the other, I used code separation for workflows and any complex custom activities, and without code separation for custom activities that just inherit from the Activity class and thus don't have anything special in the designer. So far, so good. Workflow Activity Library project type - What's the point of this separate project type? So far I don't see much advantage to keeping your custom activities in a separate project. I prefer to have as few projects as needed (and no fewer). The Designer's Toolbox window seems to find your custom activities just fine no matter where they are, and the debugging experience doesn't seem to be any different. Designer Properties - This is about the designer, and not specific to WF, but nevertheless something that's hindered me a lot more in WF than in Windows Forms or elsewhere. The Properties window does a good job of showing you property values when you hover the mouse over the values. But they don't do the same to find out what a control's type is. So maybe if I named all my activities "x1" and "x2" instead of helpful self-documenting names like "listenForStatusUpdate", then I could easily see enough of the type to determine what it is, but any names longer than those and all I get of the type is "System.Workflow.Act" or "System.Workflow.Compone". Even hitting the dropdown doesn't expand any wider, like the debugger quick watch "smart tag" popups do when you scroll through members. The only way I've found around this in VS 2008 is to widen the Properties dialog, losing precious designer real estate, then shrink it back down when you're done to see what you were doing. Really? WF Designer - This is about the designer, and I believe is specific to WF. I should be able to edit the XML in a .xoml file, or drag and drop using the designer. With WPF (at least in VS 2010 Ultimate), these are side by side, and changes to one instantly update the other. With WF, I have to right-click on the .xoml file, choose Open With, and pick XML Editor to edit the text. It looks like this is one way where WF didn't get the same attention WPF got during .NET Fx 3.0 development. Service - In the WF world, this is simply a class that talks to the workflow about things outside the workflow, not to be confused with how the term "service" is used in every other context I've seen in the Windows and .NET world, i.e. an executable that waits for events or requests from a client and services them (Windows service, web service, WCF service, etc.). ListenActivity - Such a great concept, yet so unintuitive. It seems you need at least two branches (EventDrivenActivity instances), one for your positive condition and one for a timeout. The positive condition has a HandleExternalEventActivity, and the timeout has a DelayActivity followed by however you want to handle the delay, e.g. a ThrowActivity. The timeout is simple enough; wiring up the HandleExternalEventActivity is where things get fun. You need to create a service (see above), and an interface for that service (this seems more complex than should be necessary--why not have activities just wire to a service directly?). And you need to create a custom EventArgs class that inherits from ExternalDataEventArgs--you can't create an ExternalDataEventArgs event handler directly, even if you don't need to add any more information to the event args, despite ExternalDataEventArgs not being marked as an abstract class, nor a compiler error nor warning nor any other indication that you're doing something wrong, until you run it and find that it always times out and get to check every place mentioned here to see why. Your interface and service need an event that consumes your custom EventArgs class, and a method to fire that event. You need to call that method from somewhere. Then you get to hope that you did everything just right, or that you can step through code in the debugger before your Delay timeout expires. Yes, it's as much fun as it sounds. TransactionScopeActivity - I had the bright idea of putting one in as a placeholder, then filling in the database updates later. That caused this error: The workflow hosting environment does not have a persistence service as required by an operation on the workflow instance "[GUID]". ...which is about as helpful as "Object reference not set to an instance of an object" and even more fun to debug. Google led me to this Microsoft Forums hit, and from there I figured out it didn't like that the activity had no children. Again, a Validator on TransactionScopeActivity would have pointed this out to me at design time, rather than handing me a nearly useless error at runtime. Easily enough, I disabled the activity and that fixed it. I still see huge potential in my work where WF could make things easier and more flexible, but there are some seriously rough edges at the moment. Maybe I'm just spoiled by how much easier and more intuitive development elsewhere in the .NET Framework is.

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• Making your WCF Web Apis to speak in multiple languages

  - by cibrax

  One of the key aspects of how the web works today is content negotiation. The idea of content negotiation is based on the fact that a single resource can have multiple representations, so user agents (or clients) and servers can work together to chose one of them. The http specification defines several “Accept” headers that a client can use to negotiate content with a server, and among all those, there is one for restricting the set of natural languages that are preferred as a response to a request, “Accept-Language”. For example, a client can specify “es” in this header for specifying that he prefers to receive the content in spanish or “en” in english. However, there are certain scenarios where the “Accept-Language” header is just not enough, and you might want to have a way to pass the “accepted” language as part of the resource url as an extension. For example, http://localhost/ProductCatalog/Products/1.es” returns all the descriptions for the product with id “1” in spanish. This is useful for scenarios in which you want to embed the link somewhere, such a document, an email or a page.  Supporting both scenarios, the header and the url extension, is really simple in the new WCF programming model. You only need to provide a processor implementation for any of them. Let’s say I have a resource implementation as part of a product catalog I want to expose with the WCF web apis. [ServiceContract][Export]public class ProductResource{ IProductRepository repository;  [ImportingConstructor] public ProductResource(IProductRepository repository) { this.repository = repository; }  [WebGet(UriTemplate = "{id}")] public Product Get(string id, HttpResponseMessage response) { var product = repository.GetById(int.Parse(id)); if (product == null) { response.StatusCode = HttpStatusCode.NotFound; response.Content = new StringContent(Messages.OrderNotFound); }  return product; }} The Get method implementation in this resource assumes the desired culture will be attached to the current thread (Thread.CurrentThread.Culture). Another option is to pass the desired culture as an additional argument in the method, so my processor implementation will handle both options. This method is also using an auto-generated class for handling string resources, Messages, which is available in the different cultures that the service implementation supports. For example, Messages.resx contains “OrderNotFound”: “Order Not Found” Messages.es.resx contains “OrderNotFound”: “No se encontro orden” The processor implementation bellow tackles the first scenario, in which the desired language is passed as part of the “Accept-Language” header. public class CultureProcessor : Processor<HttpRequestMessage, CultureInfo>{ string defaultLanguage = null;  public CultureProcessor(string defaultLanguage = "en") { this.defaultLanguage = defaultLanguage; this.InArguments[0].Name = HttpPipelineFormatter.ArgumentHttpRequestMessage; this.OutArguments[0].Name = "culture"; }  public override ProcessorResult<CultureInfo> OnExecute(HttpRequestMessage request) { CultureInfo culture = null; if (request.Headers.AcceptLanguage.Count > 0) { var language = request.Headers.AcceptLanguage.First().Value; culture = new CultureInfo(language); } else { culture = new CultureInfo(defaultLanguage); }  Thread.CurrentThread.CurrentCulture = culture; Messages.Culture = culture;  return new ProcessorResult<CultureInfo> { Output = culture }; }}   As you can see, the processor initializes a new CultureInfo instance with the value provided in the “Accept-Language” header, and set that instance to the current thread and the auto-generated resource class with all the messages. In addition, the CultureInfo instance is returned as an output argument called “culture”, making possible to receive that argument in any method implementation   The following code shows the implementation of the processor for handling languages as url extensions.   public class CultureExtensionProcessor : Processor<HttpRequestMessage, Uri>{ public CultureExtensionProcessor() { this.OutArguments[0].Name = HttpPipelineFormatter.ArgumentUri; }  public override ProcessorResult<Uri> OnExecute(HttpRequestMessage httpRequestMessage) { var requestUri = httpRequestMessage.RequestUri.OriginalString;  var extensionPosition = requestUri.LastIndexOf(".");  if (extensionPosition > -1) { var extension = requestUri.Substring(extensionPosition + 1);  var query = httpRequestMessage.RequestUri.Query;  requestUri = string.Format("{0}?{1}", requestUri.Substring(0, extensionPosition), query); ;  var uri = new Uri(requestUri);  httpRequestMessage.Headers.AcceptLanguage.Clear();  httpRequestMessage.Headers.AcceptLanguage.Add(new StringWithQualityHeaderValue(extension));  var result = new ProcessorResult<Uri>();  result.Output = uri;  return result; }  return new ProcessorResult<Uri>(); }} The last step is to inject both processors as part of the service configuration as it is shown bellow, public void RegisterRequestProcessorsForOperation(HttpOperationDescription operation, IList<Processor> processors, MediaTypeProcessorMode mode){ processors.Insert(0, new CultureExtensionProcessor()); processors.Add(new CultureProcessor());} Once you configured the two processors in the pipeline, your service will start speaking different languages :). Note: Url extensions don’t seem to be working in the current bits when you are using Url extensions in a base address. As far as I could see, ASP.NET intercepts the request first and tries to route the request to a registered ASP.NET Http Handler with that extension. For example, “http://localhost/ProductCatalog/products.es” does not work, but “http://localhost/ProductCatalog/products/1.es” does.

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• ASP.NET MVC3 checkbox dropdownlist create [migrated]

  - by user95381

  i'm new in asp.net MVC and I/m use view model to poppulate the dropdown list and group of checkboxes. I use SQL Server 2012, where have many to many relationships between Students - Books; Student - Cities. I need collect StudentName, one city and many books for one student. I have next questions: 1. How can I get the values from database to my StudentBookCityViewModel? 2. How can I save the values to my database in [HttpPost] Create method? Here is the code: MODEL public class Student { public int StudentId { get; set; } public string StudentName { get; set; } public ICollection<Book> Books { get; set; } public ICollection<City> Cities { get; set; } } public class Book { public int BookId { get; set; } public string BookName { get; set; } public bool IsSelected { get; set; } public ICollection<Student> Students { get; set; } } public class City { public int CityId { get; set; } public string CityName { get; set; } public bool IsSelected { get; set; } public ICollection<Student> Students { get; set; } } VIEW MODEL public class StudentBookCityViewModel { public string StudentName { get; set; } public IList<Book> Books { get; set; } public StudentBookCityViewModel() { Books = new[] { new Book {BookName = "Title1", IsSelected = false}, new Book {BookName = "Title2", IsSelected = false}, new Book {BookName = "Title3", IsSelected = false} }.ToList(); } public string City { get; set; } public IEnumerable<SelectListItem> CityValues { get { return new[] { new SelectListItem {Value = "Value1", Text = "Text1"}, new SelectListItem {Value = "Value2", Text = "Text2"}, new SelectListItem {Value = "Value3", Text = "Text3"} }; } } } Context public class EFDbContext : DbContext{ public EFDbContext(string connectionString) { Database.Connection.ConnectionString = connectionString; } public DbSet<Book> Books { get; set; } public DbSet<Student> Students { get; set; } public DbSet<City> Cities { get; set; } protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Entity<Book>() .HasMany(x => x.Students).WithMany(x => x.Books) .Map(x => x.MapLeftKey("BookId").MapRightKey("StudentId").ToTable("StudentBooks")); modelBuilder.Entity<City>() .HasMany(x => x.Students).WithMany(x => x.Cities) .Map(x => x.MapLeftKey("CityId").MapRightKey("StudentId").ToTable("StudentCities")); } } Controller public ActionResult Create() { return View(); } [HttpPost] public ActionResult Create() { //I don't understand how I can save values to db context.SaveChanges(); return RedirectToAction("Index"); } View @model UsingEFNew.ViewModels.StudentBookCityViewModel @using (Html.BeginForm()) { Your Name: @Html.TextBoxFor(model = model.StudentName) <div>Genre:</div> <div> @Html.DropDownListFor(model => model.City, Model.CityValues) </div> <div>Books:</div> <div> @for (int i = 0; i < Model.Books.Count; i++) { <div> @Html.HiddenFor(x => x.Books[i].BookId) @Html.CheckBoxFor(x => x.Books[i].IsSelected) @Html.LabelFor(x => x.Books[i].IsSelected, Model.Books[i].BookName) </div> } </div> <div> <input id="btnSubmit" type="submit" value="Submit" /> </div> </div> }

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• Get XML from Server for Use on Windows Phone

  - by psheriff

  When working with mobile devices you always need to take into account bandwidth usage and power consumption. If you are constantly connecting to a server to retrieve data for an input screen, then you might think about moving some of that data down to the phone and cache the data on the phone. An example would be a static list of US State Codes that you are asking the user to select from. Since this is data that does not change very often, this is one set of data that would be great to cache on the phone. Since the Windows Phone does not have an embedded database, you can just use an XML string stored in Isolated Storage. Of course, then you need to figure out how to get data down to the phone. You can either ship it with the application, or connect and retrieve the data from your server one time and thereafter cache it and retrieve it from the cache. In this blog post you will see how to create a WCF service to retrieve data from a Product table in a database and send that data as XML to the phone and store it in Isolated Storage. You will then read that data from Isolated Storage using LINQ to XML and display it in a ListBox. Step 1: Create a Windows Phone Application The first step is to create a Windows Phone application called WP_GetXmlFromDataSet (or whatever you want to call it). On the MainPage.xaml add the following XAML within the “ContentPanel” grid: <StackPanel>  <Button Name="btnGetXml"          Content="Get XML"          Click="btnGetXml_Click" />  <Button Name="btnRead"          Content="Read XML"          IsEnabled="False"          Click="btnRead_Click" />  <ListBox Name="lstData"            Height="430"            ItemsSource="{Binding}"            DisplayMemberPath="ProductName" /></StackPanel> Now it is time to create the WCF Service Application that you will call to get the XML from a table in a SQL Server database. Step 2: Create a WCF Service Application Add a new project to your solution called WP_GetXmlFromDataSet.Services. Delete the IService1.* and Service1.* files and the App_Data folder, as you don’t generally need these items. Add a new WCF Service class called ProductService. In the IProductService class modify the void DoWork() method with the following code: [OperationContract]string GetProductXml(); Open the code behind in the ProductService.svc and create the GetProductXml() method. This method (shown below) will connect up to a database and retrieve data from a Product table. public string GetProductXml(){  string ret = string.Empty;  string sql = string.Empty;  SqlDataAdapter da;  DataSet ds = new DataSet();   sql = "SELECT ProductId, ProductName,";  sql += " IntroductionDate, Price";  sql += " FROM Product";   da = new SqlDataAdapter(sql,    ConfigurationManager.ConnectionStrings["Sandbox"].ConnectionString);   da.Fill(ds);   // Create Attribute based XML  foreach (DataColumn col in ds.Tables[0].Columns)  {    col.ColumnMapping = MappingType.Attribute;  }   ds.DataSetName = "Products";  ds.Tables[0].TableName = "Product";  ret = ds.GetXml();   return ret;} After retrieving the data from the Product table using a DataSet, you will want to set each column’s ColumnMapping property to Attribute. Using attribute based XML will make the data transferred across the wire a little smaller. You then set the DataSetName property to the top-level element name you want to assign to the XML. You then set the TableName property on the DataTable to the name you want each element to be in your XML. The last thing you need to do is to call the GetXml() method on the DataSet object which will return an XML string of the data in your DataSet object. This is the value that you will return from the service call. The XML that is returned from the above call looks like the following: <Products>  <Product ProductId="1"           ProductName="PDSA .NET Productivity Framework"           IntroductionDate="9/3/2010"           Price="5000" />  <Product ProductId="3"           ProductName="Haystack Code Generator for .NET"           IntroductionDate="7/1/2010"           Price="599.00" />  ...  ...  ... </Products> The GetProductXml() method uses a connection string from the Web.Config file, so add a <connectionStrings> element to the Web.Config file in your WCF Service application. Modify the settings shown below as needed for your server and database name. <connectionStrings>  <add name="Sandbox"        connectionString="Server=Localhost;Database=Sandbox;                         Integrated Security=Yes"/></connectionStrings> The Product Table You will need a Product table that you can read data from. I used the following structure for my product table. Add any data you want to this table after you create it in your database. CREATE TABLE Product(  ProductId int PRIMARY KEY IDENTITY(1,1) NOT NULL,  ProductName varchar(50) NOT NULL,  IntroductionDate datetime NULL,  Price money NULL) Step 3: Connect to WCF Service from Windows Phone Application Back in your Windows Phone application you will now need to add a Service Reference to the WCF Service application you just created. Right-mouse click on the Windows Phone Project and choose Add Service Reference… from the context menu. Click on the Discover button. In the Namespace text box enter “ProductServiceRefrence”, then click the OK button. If you entered everything correctly, Visual Studio will generate some code that allows you to connect to your Product service. On the MainPage.xaml designer window double click on the Get XML button to generate the Click event procedure for this button. In the Click event procedure make a call to a GetXmlFromServer() method. This method will also need a “Completed” event procedure to be written since all communication with a WCF Service from Windows Phone must be asynchronous.  Write these two methods as follows: private const string KEY_NAME = "ProductData"; private void GetXmlFromServer(){  ProductServiceClient client = new ProductServiceClient();   client.GetProductXmlCompleted += new     EventHandler<GetProductXmlCompletedEventArgs>      (client_GetProductXmlCompleted);   client.GetProductXmlAsync();  client.CloseAsync();} void client_GetProductXmlCompleted(object sender,                                   GetProductXmlCompletedEventArgs e){  // Store XML data in Isolated Storage  IsolatedStorageSettings.ApplicationSettings[KEY_NAME] = e.Result;   btnRead.IsEnabled = true;} As you can see, this is a fairly standard call to a WCF Service. In the Completed event you get the Result from the event argument, which is the XML, and store it into Isolated Storage using the IsolatedStorageSettings.ApplicationSettings class. Notice the constant that I added to specify the name of the key. You will use this constant later to read the data from Isolated Storage. Step 4: Create a Product Class Even though you stored XML data into Isolated Storage when you read that data out you will want to convert each element in the XML file into an actual Product object. This means that you need to create a Product class in your Windows Phone application. Add a Product class to your project that looks like the code below: public class Product{  public string ProductName{ get; set; }  public int ProductId{ get; set; }  public DateTime IntroductionDate{ get; set; }  public decimal Price{ get; set; }} Step 5: Read Settings from Isolated Storage Now that you have the XML data stored in Isolated Storage, it is time to use it. Go back to the MainPage.xaml design view and double click on the Read XML button to generate the Click event procedure. From the Click event procedure call a method named ReadProductXml().Create this method as shown below: private void ReadProductXml(){  XElement xElem = null;   if (IsolatedStorageSettings.ApplicationSettings.Contains(KEY_NAME))  {    xElem = XElement.Parse(     IsolatedStorageSettings.ApplicationSettings[KEY_NAME].ToString());     // Create a list of Product objects    var products =         from prod in xElem.Descendants("Product")        orderby prod.Attribute("ProductName").Value        select new Product        {          ProductId = Convert.ToInt32(prod.Attribute("ProductId").Value),          ProductName = prod.Attribute("ProductName").Value,          IntroductionDate =             Convert.ToDateTime(prod.Attribute("IntroductionDate").Value),          Price = Convert.ToDecimal(prod.Attribute("Price").Value)        };     lstData.DataContext = products;  }} The ReadProductXml() method checks to make sure that the key name that you saved your XML as exists in Isolated Storage prior to trying to open it. If the key name exists, then you retrieve the value as a string. Use the XElement’s Parse method to convert the XML string to a XElement object. LINQ to XML is used to iterate over each element in the XElement object and create a new Product object from each attribute in your XML file. The LINQ to XML code also orders the XML data by the ProductName. After the LINQ to XML code runs you end up with an IEnumerable collection of Product objects in the variable named “products”. You assign this collection of product data to the DataContext of the ListBox you created in XAML. The DisplayMemberPath property of the ListBox is set to “ProductName” so it will now display the product name for each row in your products collection. Summary In this article you learned how to retrieve an XML string from a table in a database, return that string across a WCF Service and store it into Isolated Storage on your Windows Phone. You then used LINQ to XML to create a collection of Product objects from the data stored and display that data in a Windows Phone list box. This same technique can be used in Silverlight or WPF applications too. NOTE: You can download the complete sample code at my website. http://www.pdsa.com/downloads. Choose Tips & Tricks, then "Get XML From Server for Use on Windows Phone" from the drop-down. Good Luck with your Coding,Paul Sheriff ** SPECIAL OFFER FOR MY BLOG READERS **Visit http://www.pdsa.com/Event/Blog for a free video on Silverlight entitled Silverlight XAML for the Complete Novice - Part 1.  

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• Android - Switching Activities with a Tab Layout

  - by Bill Osuch

  This post is based on the Tab Layout  tutorial on the Android developers site, with some modifications. I wanted to get rid of the icons (they take up too much screen real estate), and modify the fonts on the tabs. First, create a new Android project, with an Activity called TabWidget. Then, create two additional Activities called TabOne and TabTwo. Throw a simple TextView on each one with a message identifying the tab, like this: public class TabTwo extends Activity {  @Override  public void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   TextView tv = new TextView(this);   tv.setText("This is tab 2");   setContentView(tv);  } } And don't forget to add them to your AndroidManifest.xml file: <activity android:name=".TabOne"></activity> <activity android:name=".TabTwo"></activity> Now we'll create the tab layout - open the res/layout/main.xml file and insert the following: <?xml version="1.0" encoding="utf-8"?> <TabHost xmlns:android="http://schemas.android.com/apk/res/android"  android:id="@android:id/tabhost"  android:layout_width="fill_parent"  android:layout_height="fill_parent">  <LinearLayout   android:orientation="vertical"   android:layout_width="fill_parent"   android:layout_height="fill_parent">   <TabWidget    android:id="@android:id/tabs"    android:layout_width="fill_parent"    android:layout_height="wrap_content" />   <FrameLayout    android:id="@android:id/tabcontent"             android:layout_width="fill_parent"    android:layout_height="fill_parent" />  </LinearLayout> </TabHost> Finally, we'll create the code needed to populate the TabHost. Make sure your TabWidget class extends TabActivity rather than Activity, and add code to grab the TabHost and create an Intent to launch a new Activity:    TabHost tabHost = getTabHost();  // The activity TabHost    TabHost.TabSpec spec;  // Reusable TabSpec for each tab    Intent intent;  // Reusable Intent for each tab       // Create an Intent to launch an Activity for the tab (to be reused)    intent = new Intent().setClass(this, TabOne.class); Add the first tab to the layout:    // Initialize a TabSpec for each tab and add it to the TabHost    spec = tabHost.newTabSpec("tabOne");      spec.setContent(intent);     spec.setIndicator("Tab One");     tabHost.addTab(spec); It's pretty tall as-is, so we'll shorten it:   // Squish the tab a little bit horizontally   tabHost.getTabWidget().getChildAt(0).getLayoutParams().height = 40; But the text is a little small, so let's increase the font size:   // Bump the text size up   LinearLayout ll = (LinearLayout) tabHost.getChildAt(0);   android.widget.TabWidget tw = (android.widget.TabWidget) ll.getChildAt(0);   RelativeLayout rllf = (RelativeLayout) tw.getChildAt(0);   TextView lf = (TextView) rllf.getChildAt(1);   lf.setTextSize(20); Do the same for the second tab, and you wind up with this: @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.main);                 TabHost tabHost = getTabHost();  // The activity TabHost         TabHost.TabSpec spec;  // Reusable TabSpec for each tab         Intent intent;  // Reusable Intent for each tab            // Create an Intent to launch an Activity for the tab (to be reused)         intent = new Intent().setClass(this, TabOne.class);         // Initialize a TabSpec for each tab and add it to the TabHost         spec = tabHost.newTabSpec("tabOne");           spec.setContent(intent);          spec.setIndicator("Tab One");          tabHost.addTab(spec);         // Squish the tab a little bit horizontally         tabHost.getTabWidget().getChildAt(0).getLayoutParams().height = 40;         // Bump the text size up         LinearLayout ll = (LinearLayout) tabHost.getChildAt(0);         android.widget.TabWidget tw = (android.widget.TabWidget) ll.getChildAt(0);         RelativeLayout rllf = (RelativeLayout) tw.getChildAt(0);         TextView lf = (TextView) rllf.getChildAt(1);         lf.setTextSize(20);            // Do the same for the other tabs         intent = new Intent().setClass(this, TabTwo.class);         spec = tabHost.newTabSpec("tabTwo");          spec.setContent(intent);          spec.setIndicator("Tab Two");         tabHost.addTab(spec);         tabHost.getTabWidget().getChildAt(1).getLayoutParams().height = 40;         RelativeLayout rlrf = (RelativeLayout) tw.getChildAt(1);         TextView rf = (TextView) rlrf.getChildAt(1);         rf.setTextSize(20);            tabHost.setCurrentTab(0);     } Save and fire up the emulator, and you should be able to switch back and forth between your tabs!

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• Understanding C# async / await (1) Compilation

  - by Dixin

  Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is called MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been cleaned up so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# level syntax sugar. There is no difference to await a async method or a normal method. A method returning Task will be awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } The above code is already cleaned up, but there are still a lot of things. More clean up can be done, and the state machine can be very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> void IAsyncStateMachine.MoveNext() { try { switch (this.State) { // Orginal code is splitted by "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; IAsyncStateMachine this1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this1.MoveNext()); // Callback break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; IAsyncStateMachine this2 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this2.MoveNext()); // Callback break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync_(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; (multiCallMethodAsyncStateMachine as IAsyncStateMachine).MoveNext(); // Original code are in this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clear - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback Since it is about callback, the simplification  can go even further – the entire state machine can be completely purged. Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is literally pretending to wait. In a await expression, a Task object will be return immediately so that caller is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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• ASPNET WebAPI REST Guidance

  - by JoshReuben

  ASP.NET Web API is an ideal platform for building RESTful applications on the .NET Framework. While I may be more partial to NodeJS these days, there is no denying that WebAPI is a well engineered framework. What follows is my investigation of how to leverage WebAPI to construct a RESTful frontend API.   The Advantages of REST Methodology over SOAP Simpler API for CRUD ops Standardize Development methodology - consistent and intuitive Standards based à client interop Wide industry adoption, Ease of use à easy to add new devs Avoid service method signature blowout Smaller payloads than SOAP Stateless à no session data means multi-tenant scalability Cache-ability Testability   General RESTful API Design Overview · utilize HTTP Protocol - Usage of HTTP methods for CRUD, standard HTTP response codes, common HTTP headers and Mime Types · Resources are mapped to URLs, actions are mapped to verbs and the rest goes in the headers. · keep the API semantic, resource-centric – A RESTful, resource-oriented service exposes a URI for every piece of data the client might want to operate on. A REST-RPC Hybrid exposes a URI for every operation the client might perform: one URI to fetch a piece of data, a different URI to delete that same data. utilize Uri to specify CRUD op, version, language, output format: http://api.MyApp.com/{ver}/{lang}/{resource_type}/{resource_id}.{output_format}?{key&filters} · entity CRUD operations are matched to HTTP methods: · Create - POST / PUT · Read – GET - cacheable · Update – PUT · Delete - DELETE · Use Uris to represent a hierarchies - Resources in RESTful URLs are often chained · Statelessness allows for idempotency – apply an op multiple times without changing the result. POST is non-idempotent, the rest are idempotent (if DELETE flags records instead of deleting them). · Cache indication - Leverage HTTP headers to label cacheable content and indicate the permitted duration of cache · PUT vs POST - The client uses PUT when it determines which URI (Id key) the new resource should have. The client uses POST when the server determines they key. PUT takes a second param – the id. POST creates a new resource. The server assigns the URI for the new object and returns this URI as part of the response message. Note: The PUT method replaces the entire entity. That is, the client is expected to send a complete representation of the updated product. If you want to support partial updates, the PATCH method is preferred DELETE deletes a resource at a specified URI – typically takes an id param · Leverage Common HTTP Response Codes in response headers 200 OK: Success 201 Created - Used on POST request when creating a new resource. 304 Not Modified: no new data to return. 400 Bad Request: Invalid Request. 401 Unauthorized: Authentication. 403 Forbidden: Authorization 404 Not Found – entity does not exist. 406 Not Acceptable – bad params. 409 Conflict - For POST / PUT requests if the resource already exists. 500 Internal Server Error 503 Service Unavailable · Leverage uncommon HTTP Verbs to reduce payload sizes HEAD - retrieves just the resource meta-information. OPTIONS returns the actions supported for the specified resource. PATCH - partial modification of a resource. · When using PUT, POST or PATCH, send the data as a document in the body of the request. Don't use query parameters to alter state. · Utilize Headers for content negotiation, caching, authorization, throttling o Content Negotiation – choose representation (e.g. JSON or XML and version), language & compression. Signal via RequestHeader.Accept & ResponseHeader.Content-Type Accept: application/json;version=1.0 Accept-Language: en-US Accept-Charset: UTF-8 Accept-Encoding: gzip o Caching - ResponseHeader: Expires (absolute expiry time) or Cache-Control (relative expiry time) o Authorization - basic HTTP authentication uses the RequestHeader.Authorization to specify a base64 encoded string "username:password". can be used in combination with SSL/TLS (HTTPS) and leverage OAuth2 3rd party token-claims authorization. Authorization: Basic sQJlaTp5ZWFslylnaNZ= o Rate Limiting - Not currently part of HTTP so specify non-standard headers prefixed with X- in the ResponseHeader. X-RateLimit-Limit: 10000 X-RateLimit-Remaining: 9990 · HATEOAS Methodology - Hypermedia As The Engine Of Application State – leverage API as a state machine where resources are states and the transitions between states are links between resources and are included in their representation (hypermedia) – get API metadata signatures from the response Link header - in a truly REST based architecture any URL, except the initial URL, can be changed, even to other servers, without worrying about the client. · error responses - Do not just send back a 200 OK with every response. Response should consist of HTTP error status code (JQuery has automated support for this), A human readable message , A Link to a meaningful state transition , & the original data payload that was problematic. · the URIs will typically map to a server-side controller and a method name specified by the type of request method. Stuff all your calls into just four methods is not as crazy as it sounds. · Scoping - Path variables look like you’re traversing a hierarchy, and query variables look like you’re passing arguments into an algorithm · Mapping URIs to Controllers - have one controller for each resource is not a rule – can consolidate - route requests to the appropriate controller and action method · Keep URls Consistent - Sometimes it’s tempting to just shorten our URIs. not recommend this as this can cause confusion · Join Naming – for m-m entity relations there may be multiple hierarchy traversal paths · Routing – useful level of indirection for versioning, server backend mocking in development ASPNET WebAPI Considerations ASPNET WebAPI implements a lot (but not all) RESTful API design considerations as part of its infrastructure and via its coding convention. Overview When developing an API there are basically three main steps: 1. Plan out your URIs 2. Setup return values and response codes for your URIs 3. Implement a framework for your API.   Design · Leverage Models MVC folder · Repositories – support IoC for tests, abstraction · Create DTO classes – a level of indirection decouples & allows swap out · Self links can be generated using the UrlHelper · Use IQueryable to support projections across the wire · Models can support restful navigation properties – ICollection<T> · async mechanism for long running ops - return a response with a ticket – the client can then poll or be pushed the final result later. · Design for testability - Test using HttpClient , JQuery ( $.getJSON , $.each) , fiddler, browser debug. Leverage IDependencyResolver – IoC wrapper for mocking · Easy debugging - IE F12 developer tools: Network tab, Request Headers tab     Routing · HTTP request method is matched to the method name. (This rule applies only to GET, POST, PUT, and DELETE requests.) · {id}, if present, is matched to a method parameter named id. · Query parameters are matched to parameter names when possible · Done in config via Routes.MapHttpRoute – similar to MVC routing · Can alternatively: o decorate controller action methods with HttpDelete, HttpGet, HttpHead,HttpOptions, HttpPatch, HttpPost, or HttpPut., + the ActionAttribute o use AcceptVerbsAttribute to support other HTTP verbs: e.g. PATCH, HEAD o use NonActionAttribute to prevent a method from getting invoked as an action · route table Uris can support placeholders (via curly braces{}) – these can support default values and constraints, and optional values · The framework selects the first route in the route table that matches the URI. Response customization · Response code: By default, the Web API framework sets the response status code to 200 (OK). But according to the HTTP/1.1 protocol, when a POST request results in the creation of a resource, the server should reply with status 201 (Created). Non Get methods should return HttpResponseMessage · Location: When the server creates a resource, it should include the URI of the new resource in the Location header of the response. public HttpResponseMessage PostProduct(Product item) {     item = repository.Add(item);     var response = Request.CreateResponse<Product>(HttpStatusCode.Created, item);     string uri = Url.Link("DefaultApi", new { id = item.Id });     response.Headers.Location = new Uri(uri);     return response; } Validation · Decorate Models / DTOs with System.ComponentModel.DataAnnotations properties RequiredAttribute, RangeAttribute. · Check payloads using ModelState.IsValid · Under posting – leave out values in JSON payload à JSON formatter assigns a default value. Use with RequiredAttribute · Over-posting - if model has RO properties à use DTO instead of model · Can hook into pipeline by deriving from ActionFilterAttribute & overriding OnActionExecuting Config · Done in App_Start folder > WebApiConfig.cs – static Register method: HttpConfiguration param: The HttpConfiguration object contains the following members. Member Description DependencyResolver Enables dependency injection for controllers. Filters Action filters – e.g. exception filters. Formatters Media-type formatters. by default contains JsonFormatter, XmlFormatter IncludeErrorDetailPolicy Specifies whether the server should include error details, such as exception messages and stack traces, in HTTP response messages. Initializer A function that performs final initialization of the HttpConfiguration. MessageHandlers HTTP message handlers - plug into pipeline ParameterBindingRules A collection of rules for binding parameters on controller actions. Properties A generic property bag. Routes The collection of routes. Services The collection of services. · Configure JsonFormatter for circular references to support links: PreserveReferencesHandling.Objects Documentation generation · create a help page for a web API, by using the ApiExplorer class. · The ApiExplorer class provides descriptive information about the APIs exposed by a web API as an ApiDescription collection · create the help page as an MVC view public ILookup<string, ApiDescription> GetApis()         {             return _explorer.ApiDescriptions.ToLookup(                 api => api.ActionDescriptor.ControllerDescriptor.ControllerName); · provide documentation for your APIs by implementing the IDocumentationProvider interface. Documentation strings can come from any source that you like – e.g. extract XML comments or define custom attributes to apply to the controller [ApiDoc("Gets a product by ID.")] [ApiParameterDoc("id", "The ID of the product.")] public HttpResponseMessage Get(int id) · GlobalConfiguration.Configuration.Services – add the documentation Provider · To hide an API from the ApiExplorer, add the ApiExplorerSettingsAttribute Plugging into the Message Handler pipeline · Plug into request / response pipeline – derive from DelegatingHandler and override theSendAsync method – e.g. for logging error codes, adding a custom response header · Can be applied globally or to a specific route Exception Handling · Throw HttpResponseException on method failures – specify HttpStatusCode enum value – examine this enum, as its values map well to typical op problems · Exception filters – derive from ExceptionFilterAttribute & override OnException. Apply on Controller or action methods, or add to global HttpConfiguration.Filters collection · HttpError object provides a consistent way to return error information in the HttpResponseException response body. · For model validation, you can pass the model state to CreateErrorResponse, to include the validation errors in the response public HttpResponseMessage PostProduct(Product item) {     if (!ModelState.IsValid)     {         return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState); Cookie Management · Cookie header in request and Set-Cookie headers in a response - Collection of CookieState objects · Specify Expiry, max-age resp.Headers.AddCookies(new CookieHeaderValue[] { cookie }); Internet Media Types, formatters and serialization · Defaults to application/json · Request Accept header and response Content-Type header · determines how Web API serializes and deserializes the HTTP message body. There is built-in support for XML, JSON, and form-urlencoded data · customizable formatters can be inserted into the pipeline · POCO serialization is opt out via JsonIgnoreAttribute, or use DataMemberAttribute for optin · JSON serializer leverages NewtonSoft Json.NET · loosely structured JSON objects are serialzed as JObject which derives from Dynamic · to handle circular references in json: json.SerializerSettings.PreserveReferencesHandling =    PreserveReferencesHandling.All à {"$ref":"1"}. · To preserve object references in XML [DataContract(IsReference=true)] · Content negotiation Accept: Which media types are acceptable for the response, such as “application/json,” “application/xml,” or a custom media type such as "application/vnd.example+xml" Accept-Charset: Which character sets are acceptable, such as UTF-8 or ISO 8859-1. Accept-Encoding: Which content encodings are acceptable, such as gzip. Accept-Language: The preferred natural language, such as “en-us”. o Web API uses the Accept and Accept-Charset headers. (At this time, there is no built-in support for Accept-Encoding or Accept-Language.) · Controller methods can take JSON representations of DTOs as params – auto-deserialization · Typical JQuery GET request: function find() {     var id = $('#prodId').val();     $.getJSON("api/products/" + id,         function (data) {             var str = data.Name + ': $' + data.Price;             $('#product').text(str);         })     .fail(         function (jqXHR, textStatus, err) {             $('#product').text('Error: ' + err);         }); }            · Typical GET response: HTTP/1.1 200 OK Server: ASP.NET Development Server/10.0.0.0 Date: Mon, 18 Jun 2012 04:30:33 GMT X-AspNet-Version: 4.0.30319 Cache-Control: no-cache Pragma: no-cache Expires: -1 Content-Type: application/json; charset=utf-8 Content-Length: 175 Connection: Close [{"Id":1,"Name":"TomatoSoup","Price":1.39,"ActualCost":0.99},{"Id":2,"Name":"Hammer", "Price":16.99,"ActualCost":10.00},{"Id":3,"Name":"Yo yo","Price":6.99,"ActualCost": 2.05}] True OData support · Leverage Query Options $filter, $orderby, $top and $skip to shape the results of controller actions annotated with the [Queryable]attribute. [Queryable]  public IQueryable<Supplier> GetSuppliers()  · Query: ~/Suppliers?$filter=Name eq ‘Microsoft’ · Applies the following selection filter on the server: GetSuppliers().Where(s => s.Name == “Microsoft”)  · Will pass the result to the formatter. · true support for the OData format is still limited - no support for creates, updates, deletes, $metadata and code generation etc · vnext: ability to configure how EditLinks, SelfLinks and Ids are generated Self Hosting no dependency on ASPNET or IIS: using (var server = new HttpSelfHostServer(config)) {     server.OpenAsync().Wait(); Tracing · tracability tools, metrics – e.g. send to nagios · use your choice of tracing/logging library, whether that is ETW,NLog, log4net, or simply System.Diagnostics.Trace. · To collect traces, implement the ITraceWriter interface public class SimpleTracer : ITraceWriter {     public void Trace(HttpRequestMessage request, string category, TraceLevel level,         Action<TraceRecord> traceAction)     {         TraceRecord rec = new TraceRecord(request, category, level);         traceAction(rec);         WriteTrace(rec); · register the service with config · programmatically trace – has helper extension methods: Configuration.Services.GetTraceWriter().Info( · Performance tracing - pipeline writes traces at the beginning and end of an operation - TraceRecord class includes aTimeStamp property, Kind property set to TraceKind.Begin / End Security · Roles class methods: RoleExists, AddUserToRole · WebSecurity class methods: UserExists, .CreateUserAndAccount · Request.IsAuthenticated · Leverage HTTP 401 (Unauthorized) response · [AuthorizeAttribute(Roles="Administrator")] – can be applied to Controller or its action methods · See section in WebApi document on "Claim-based-security for ASP.NET Web APIs using DotNetOpenAuth" – adapt this to STS.--> Web API Host exposes secured Web APIs which can only be accessed by presenting a valid token issued by the trusted issuer. http://zamd.net/2012/05/04/claim-based-security-for-asp-net-web-apis-using-dotnetopenauth/ · Use MVC membership provider infrastructure and add a DelegatingHandler child class to the WebAPI pipeline - http://stackoverflow.com/questions/11535075/asp-net-mvc-4-web-api-authentication-with-membership-provider - this will perform the login actions · Then use AuthorizeAttribute on controllers and methods for role mapping- http://sixgun.wordpress.com/2012/02/29/asp-net-web-api-basic-authentication/ · Alternate option here is to rely on MVC App : http://forums.asp.net/t/1831767.aspx/1

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• Understanding C# async / await (1) Compilation

  - by Dixin

  Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is named MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine, MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been refactored, so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# language level syntax sugar. There is no difference to await a async method or a normal method. As long as a method returns Task, it is awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } Once again, the above state machine code is already refactored, but it still has a lot of things. More clean up can be done if we only keep the core logic, and the state machine can become very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> public void MoveNext() // IAsyncStateMachine member. { try { switch (this.State) { // Original code is split by "await"s into "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; MultiCallMethodAsyncStateMachine that1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => that1.MoveNext()); break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; MultiCallMethodAsyncStateMachine that2 = this; this.currentTaskToAwait.ContinueWith(_ => that2.MoveNext()); break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] public void SetStateMachine(IAsyncStateMachine stateMachine) // IAsyncStateMachine member. { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; multiCallMethodAsyncStateMachine.MoveNext(); // Original code are moved into this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clean - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback If we focus on the point of callback, the simplification  can go even further – the entire state machine can be completely purged, and we can just keep the code inside MoveNext(). Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is not to wait. In a await expression, a Task object will be return immediately so that execution is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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• libgdx rotation (animation, arrays) issues and help needed

  - by johnny-b

  well i am a noob at java and libgdx. i got the homing bullet working with the help of someone. now i am smashing my head as to how i can make it rotate so it faces the ball (which is the main character) when it goes around it or when it is coming towards it. the bullet is facing <--- and the code below is what i have done so far. also i used sprites for the bullet and also animation method. Also how do i make it an array/arraylist which is best so i can have multiple bullets at random or placed places. i tried many things nothing workd :( thank you for the help. // below is the bullet or enemy if you want to call it. public class Bullet extends Sprite { public static final float BULLET_HOMING = 6000; public static final float BULLET_SPEED = 300; private Vector2 velocity; private float lifetime; public Bullet(float x, float y) { velocity = new Vector2(0, 0); setPosition(x, y); } public void update(float delta) { float targetX = GameWorld.getBall().getX(); float targetY = GameWorld.getBall().getY(); float dx = targetX - getX(); float dy = targetY - getY(); float distToTarget = (float) Math.sqrt(dx * dx + dy * dy); dx /= distToTarget; dy /= distToTarget; dx *= BULLET_HOMING; dy *= BULLET_HOMING; velocity.x += dx * delta; velocity.y += dy * delta; float vMag = (float) Math.sqrt(velocity.x * velocity.x + velocity.y * velocity.y); velocity.x /= vMag; velocity.y /= vMag; velocity.x *= BULLET_SPEED; velocity.y *= BULLET_SPEED; Vector2 v = velocity.cpy().scl(delta); setPosition(getX() + v.x, getY() + v.y); setOriginCenter(); setRotation(velocity.angle()); lifetime += delta; setRegion(AssetLoader.bulletAnimation.getKeyFrame(lifetime)); } } // this is where i load the images. public class AssetLoader { public static Animation bulletAnimation; public static Sprite bullet1, bullet2; public static void load() { texture = new Texture(Gdx.files.internal("SpriteN1.png")); texture.setFilter(TextureFilter.Nearest, TextureFilter.Nearest); bullet1 = new Sprite(texture, 380, 350, 45, 20); bullet1.flip(false, true); bullet2 = new Sprite(texture, 425, 350, 45, 20); bullet2.flip(false, true); Sprite[] bullets = { bullet1, bullet2 }; bulletAnimation = new Animation(0.06f, aims); bulletAnimation.setPlayMode(Animation.PlayMode.LOOP); } public static void dispose() { // We must dispose of the texture when we are finished. texture.dispose(); } // this is for the rendering of the images etc public class GameRenderer { private Bullet bullet; private Ball ball; public GameRenderer(GameWorld world) { myWorld = world; cam = new OrthographicCamera(); cam.setToOrtho(true, 480, 320); batcher = new SpriteBatch(); // Attach batcher to camera batcher.setProjectionMatrix(cam.combined); shapeRenderer = new ShapeRenderer(); shapeRenderer.setProjectionMatrix(cam.combined); // Call helper methods to initialize instance variables initGameObjects(); initAssets(); } private void initGameObjects() { ball = GameWorld.getBall(); bullet = myWorld.getBullet(); scroller = myWorld.getScroller(); } private void initAssets() { ballAnimation = AssetLoader.ballAnimation; bulletAnimation = AssetLoader.bulletAnimation; } public void render(float runTime) { Gdx.gl.glClearColor(0, 0, 0, 1); Gdx.gl.glClear(GL30.GL_COLOR_BUFFER_BIT); batcher.begin(); // Disable transparency // This is good for performance when drawing images that do not require // transparency. batcher.disableBlending(); // The ball needs transparency, so we enable that again. batcher.enableBlending(); batcher.draw(AssetLoader.ballAnimation.getKeyFrame(runTime), ball.getX(), ball.getY(), ball.getWidth(), ball.getHeight()); batcher.draw(AssetLoader.bulletAnimation.getKeyFrame(runTime), bullet.getX(), bullet.getY()); // End SpriteBatch batcher.end(); } } // this is to load the image etc on the screen i guess public class GameWorld { public static Ball ball; private Bullet bullet; private ScrollHandler scroller; public GameWorld() { ball = new Ball(480, 273, 32, 32); bullet = new Bullet(10, 10); scroller = new ScrollHandler(0); } public void update(float delta) { ball.update(delta); bullet.update(delta); scroller.update(delta); } public static Ball getBall() { return ball; } public ScrollHandler getScroller() { return scroller; } public Bullet getBullet() { return bullet; } } so there is the whole thing. the images are loaded via the AssetLoader then to the GameRenderer and GameWorld via the Bullet class. i am guessing that is how it is. sorry newbie so still learning. thank you in advace for the help or any advice.

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• Real-world SignalR example, ditching ghetto long polling

  - by Jeff

  One of the highlights of BUILD last week was the announcement that SignalR, a framework for real-time client to server (or cloud, if you will) communication, would be a real supported thing now with the weight of Microsoft behind it. Love the open source flava! If you aren’t familiar with SignalR, watch this BUILD session with PM Damian Edwards and dev David Fowler. Go ahead, I’ll wait. You’ll be in a happy place within the first ten minutes. If you skip to the end, you’ll see that they plan to ship this as a real first version by the end of the year. Insert slow clap here. Writing a few lines of code to move around a box from one browser to the next is a way cool demo, but how about something real-world? When learning new things, I find it difficult to be abstract, and I like real stuff. So I thought about what was in my tool box and the decided to port my crappy long-polling “there are new posts” feature of POP Forums to use SignalR. A few versions back, I added a feature where a button would light up while you were pecking out a reply if someone else made a post in the interim. It kind of saves you from that awkward moment where someone else posts some snark before you. While I was proud of the feature, I hated the implementation. When you clicked the reply button, it started polling an MVC URL asking if the last post you had matched the last one the server, and it did it every second and a half until you either replied or the server told you there was a new post, at which point it would display that button. The code was not glam: // in the reply setup PopForums.replyInterval = setInterval("PopForums.pollForNewPosts(" + topicID + ")", 1500); // called from the reply setup and the handler that fetches more posts PopForums.pollForNewPosts = function (topicID) { $.ajax({ url: PopForums.areaPath + "/Forum/IsLastPostInTopic/" + topicID, type: "GET", dataType: "text", data: "lastPostID=" + PopForums.currentTopicState.lastVisiblePost, success: function (result) { var lastPostLoaded = result.toLowerCase() == "true"; if (lastPostLoaded) { $("#MorePostsBeforeReplyButton").css("visibility", "hidden"); } else { $("#MorePostsBeforeReplyButton").css("visibility", "visible"); clearInterval(PopForums.replyInterval); } }, error: function () { } }); }; What’s going on here is the creation of an interval timer to keep calling the server and bugging it about new posts, and setting the visibility of a button appropriately. It looks like this if you’re monitoring requests in FireBug: Gross. The SignalR approach was to call a message broker when a reply was made, and have that broker call back to the listening clients, via a SingalR hub, to let them know about the new post. It seemed weird at first, but the server-side hub’s only method is to add the caller to a group, so new post notifications only go to callers viewing the topic where a new post was made. Beyond that, it’s important to remember that the hub is also the means to calling methods at the client end. Starting at the server side, here’s the hub: using Microsoft.AspNet.SignalR.Hubs; namespace PopForums.Messaging { public class Topics : Hub { public void ListenTo(int topicID) { Groups.Add(Context.ConnectionId, topicID.ToString()); } } } Have I mentioned how awesomely not complicated this is? The hub acts as the channel between the server and the client, and you’ll see how JavaScript calls the above method in a moment. Next, the broker class and its associated interface: using Microsoft.AspNet.SignalR; using Topic = PopForums.Models.Topic; namespace PopForums.Messaging { public interface IBroker { void NotifyNewPosts(Topic topic, int lasPostID); } public class Broker : IBroker { public void NotifyNewPosts(Topic topic, int lasPostID) { var context = GlobalHost.ConnectionManager.GetHubContext<Topics>(); context.Clients.Group(topic.TopicID.ToString()).notifyNewPosts(lasPostID); } } } The NotifyNewPosts method uses the static GlobalHost.ConnectionManager.GetHubContext<Topics>() method to get a reference to the hub, and then makes a call to clients in the group matched by the topic ID. It’s calling the notifyNewPosts method on the client. The TopicService class, which handles the reply data from the MVC controller, has an instance of the broker new’d up by dependency injection, so it took literally one line of code in the reply action method to get things moving. _broker.NotifyNewPosts(topic, post.PostID); The JavaScript side of things wasn’t much harder. When you click the reply button (or quote button), the reply window opens up and fires up a connection to the hub: var hub = $.connection.topics; hub.client.notifyNewPosts = function (lastPostID) { PopForums.setReplyMorePosts(lastPostID); }; $.connection.hub.start().done(function () { hub.server.listenTo(topicID); }); The important part to look at here is the creation of the notifyNewPosts function. That’s the method that is called from the server in the Broker class above. Conversely, once the connection is done, the script calls the listenTo method on the server, letting it know that this particular connection is listening for new posts on this specific topic ID. This whole experiment enables a lot of ideas that would make the forum more Facebook-like, letting you know when stuff is going on around you.

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• Trying to implement fling events on an object

  - by Adam Short

  I have a game object, well a bitmap, which I'd like to "fling". I'm struggling to get it to fling ontouchlistener due to it being a bitmap and not sure how to proceed and I'm struggling to find the resources to help. Here's my code so far: https://github.com/addrum/Shapes GameActivity class: package com.main.shapes; import android.app.Activity; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.os.Bundle; import android.view.GestureDetector; import android.view.MotionEvent; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.View.OnTouchListener; import android.view.Window; public class GameActivity extends Activity { private GestureDetector gestureDetector; View view; Bitmap ball; float x, y; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //Remove title bar this.requestWindowFeature(Window.FEATURE_NO_TITLE); view = new View(this); ball = BitmapFactory.decodeResource(getResources(), R.drawable.ball); gestureDetector = new GestureDetector(this, new GestureListener()); x = 0; y = 0; setContentView(view); ball.setOnTouchListener(new OnTouchListener() { @Override public boolean onTouch(android.view.View v, MotionEvent event) { // TODO Auto-generated method stub return false; } }); } @Override protected void onPause() { super.onPause(); view.pause(); } @Override protected void onResume() { super.onResume(); view.resume(); } public class View extends SurfaceView implements Runnable { Thread thread = null; SurfaceHolder holder; boolean canRun = false; public View(Context context) { super(context); holder = getHolder(); } public void run() { while (canRun) { if (!holder.getSurface().isValid()) { continue; } Canvas c = holder.lockCanvas(); c.drawARGB(255, 255, 255, 255); c.drawBitmap(ball, x - (ball.getWidth() / 2), y - (ball.getHeight() / 2), null); holder.unlockCanvasAndPost(c); } } public void pause() { canRun = false; while (true) { try { thread.join(); } catch (InterruptedException e) { e.printStackTrace(); } break; } thread = null; } public void resume() { canRun = true; thread = new Thread(this); thread.start(); } } } GestureListener class: package com.main.shapes; import android.view.GestureDetector.SimpleOnGestureListener; import android.view.MotionEvent; public class GestureListener extends SimpleOnGestureListener { private static final int SWIPE_MIN_DISTANCE = 120; private static final int SWIPE_THRESHOLD_VELOCITY = 200; @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { if (e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) { //From Right to Left return true; } else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) { //From Left to Right return true; } if (e1.getY() - e2.getY() > SWIPE_MIN_DISTANCE && Math.abs(velocityY) > SWIPE_THRESHOLD_VELOCITY) { //From Bottom to Top return true; } else if (e2.getY() - e1.getY() > SWIPE_MIN_DISTANCE && Math.abs(velocityY) > SWIPE_THRESHOLD_VELOCITY) { //From Top to Bottom return true; } return false; } @Override public boolean onDown(MotionEvent e) { //always return true since all gestures always begin with onDown and<br> //if this returns false, the framework won't try to pick up onFling for example. return true; } }

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• WebSocket API 1.1 released!

  - by Pavel Bucek

  Its my please to announce that JSR 356 – Java API for WebSocket maintenance release ballot vote finished with majority of “yes” votes (actually, only one eligible voter did not vote, all other votes were “yeses”). New release is maintenance release and it addresses only one issue:  WEBSOCKET_SPEC-226. What changed in the 1.1? Version 1.1 is fully backwards compatible with version 1.0, there are only two methods added to javax.websocket.Session: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 /** * Register to handle to incoming messages in this conversation. A maximum of one message handler per * native websocket message type (text, binary, pong) may be added to each Session. I.e. a maximum * of one message handler to handle incoming text messages a maximum of one message handler for * handling incoming binary messages, and a maximum of one for handling incoming pong * messages. For further details of which message handlers handle which of the native websocket * message types please see {@link MessageHandler.Whole} and {@link MessageHandler.Partial}. * Adding more than one of any one type will result in a runtime exception. * * @param clazz   type of the message processed by message handler to be registered. * @param handler whole message handler to be added. * @throws IllegalStateException if there is already a MessageHandler registered for the same native *                               websocket message type as this handler. */ public void addMessageHandler(Class<T> clazz, MessageHandler.Whole<T> handler); /** * Register to handle to incoming messages in this conversation. A maximum of one message handler per * native websocket message type (text, binary, pong) may be added to each Session. I.e. a maximum * of one message handler to handle incoming text messages a maximum of one message handler for * handling incoming binary messages, and a maximum of one for handling incoming pong * messages. For further details of which message handlers handle which of the native websocket * message types please see {@link MessageHandler.Whole} and {@link MessageHandler.Partial}. * Adding more than one of any one type will result in a runtime exception. * * * @param clazz   type of the message processed by message handler to be registered. * @param handler partial message handler to be added. * @throws IllegalStateException if there is already a MessageHandler registered for the same native *                               websocket message type as this handler. */ public void addMessageHandler(Class<T> clazz, MessageHandler.Partial<T> handler); Why do we need to add those methods? Short and not precise version: to support Lambda expressions as MessageHandlers. Longer and slightly more precise explanation: old Session#addMessageHandler method (which is still there and works as it worked till now) does rely on getting the generic parameter during the runtime, which is not (always) possible. The unfortunate part is that it works for some common cases and the expert group did not catch this issue before 1.0 release because of that. The issue is really clearly visible when Lambdas are used as message handlers: 1 2 3 session.addMessageHandler(message -> { System.out.println("### Received: " + message); }); There is no way for the JSR 356 implementation to get the type of the used Lambda expression, thus this call will always result in an exception. Since all modern IDEs do recommend to use Lambda expressions when possible and MessageHandler interfaces are single method interfaces, it basically just scream “use Lambdas” all over the place but when you do that, the application will fail during runtime. Only solution we currently have is to explicitly provide the type of registered MessageHandler. (There might be another sometime in the future when generic type reification is introduced, but that is not going to happen soon enough). So the example above will then be: 1 2 3 session.addMessageHandler(String.class, message -> { System.out.println("### Received: " + message); }); and voila, it works. There are some limitations – you cannot do 1 List<String>.class , so you will need to encapsulate these types when you want to use them in MessageHandler implementation (something like “class MyType extends ArrayList<String>”). There is no better way how to solve this issue, because Java currently does not provide good way how to describe generic types. The api itself is available on maven central, look for javax.websocket:javax.websocket-api:1.1. The reference implementation is project Tyrus, which implements WebSocket API 1.1 from version 1.8.

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• HTML5 CSS3 layout not working

  - by John.Weland

  I have been asked by a local MMA (Mixed Martial Arts) School to help them develop a website. For the life of me I CANNOT get the layout to work correctly. When I get one section set where it should be another moves out of place! here is a pic of the layout: here The header should be a set height as should the footer the entire site at its widest point should be 1250px with the header/content area/footer and the like being 1240px the black in the picture is a scaling background to expand wider as larger resolution systems are viewing them. The full site should be a minimum-height of 100% but scale virtually as content in the target area deems necessary. My biggest issue currently is that my "sticky" footer doesn't stick once the content has stretched the content target area virtually. the Code is not pretty but here it is: HTML5 <!doctype html> <html> <head> <link rel="stylesheet" href="menu.css" type="text/css" media="screen"> <link rel="stylesheet" href="master.css" type="text/css" media="screen"> <meta charset="utf-8"> <title>Untitled Document</title> </head> <body bottommargin="0" leftmargin="0" rightmargin="0" topmargin="0"> <div id="wrap" class="wrap"><div id="logo" class="logo"><img src="images/comalogo.png" width="100" height="150"></div> <div id="header" class="header">College of Martial Arts</div> <div id="nav" class="nav"> <ul id="menu"><b> <li><a href="#">News</a></li> <li>·</li> <li><a href="#">About Us</a> <ul> <li><a href="#">The Instructors</a></li> <li><a href="#">Our Arts</a></li> </li> </ul> <li>·</li> <li><a href="#">Location</a></li> <li>·</li> <li><a href="#">Gallery</a></li> <li>·</li> <li><a href="#">MMA.tv</a></li> <li>·</li> <li><a href="#">Schedule</a></li> <li>·</li> <li><a href="#">Fight Gear</a></li></b> </div> <div id="social" class="social"> <a href="http://www.facebook.com/pages/Canyon-Lake-College-of-Martial-Arts/189432551104674"><img src="images/soc/facebook.png"></a> <a href="https://twitter.com/#!/CanyonLakeMMA"><img src="images/soc/twitter.png"></a> <a href="https://plus.google.com/108252414577423199314/"><img src="images/soc/google+.png"></a> <a href="http://youtube.com/user/clmmatv"><img src="images/soc/youtube.png"></a></div> <div id="mid" class="mid">test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br>test <br></div> <div id="footer" class="footer"> <div id="contact" style="left:0px;">tel: (830) 214-4591<br /> e: [email protected]<br /> add: 1273 FM 2673, Sattler, TX 78133<br /> </div> <div id="affiliates" style="right:0px;">Hwa Rang World Tang soo Do</div> <div id="copyright">Copyright © College of Martial Arts</div> </div> </body> </html> CSS3 -Dropdown Menu- @charset "utf-8"; /* CSS Document */ /* Main */ #menu { width: 100%; margin: 0; padding: 10px 0 0 0; list-style: none; background: #444; background: -moz-linear-gradient(#000, #333); background: -webkit-gradient(linear,left bottom,left top,color-stop(0, #444),color-stop(1, #000)); background: -webkit-linear-gradient(#000, #333); background: -o-linear-gradient(#000, #333); background: -ms-linear-gradient(#000, #333); background: linear-gradient(#000, #333); -moz-border-radius: 5px; border-radius: 5px; -moz-box-shadow: 0 2px 1px #9c9c9c; -webkit-box-shadow: 0 2px 1px #9c9c9c; box-shadow: 0 8px 8px #9c9c9c; /* outline:#000 solid thin; */ } #menu li { left:150px; float: left; padding: 0 0 10px 0; position:relative; color: #FC0; font-size:15px; font-family:'freshman' cursive; line-height:15px; } #menu a { float: left; height: 15px; line-height:15px; padding: 0 10px; color: #FC0; font-size:15px; text-decoration: none; text-shadow: 1 1px 0 #000; text-align:center; } #menu li:hover > a { color: #fafafa; } *html #menu li a:hover /* IE6 */ { color: #fafafa; } #menu li:hover > ul { display: block; } /* Sub-menu */ #menu ul { list-style: none; margin: 0; padding: 0; display: none; position: absolute; top: 25px; left: 0; z-index: 99999; background: #444; background: -moz-linear-gradient(#000, #333); background: -webkit-gradient(linear,left bottom,left top,color-stop(0, #111),color-stop(1, #444)); background: -webkit-linear-gradient(#000, #333); background: -o-linear-gradient(#000, #333); background: -ms-linear-gradient(#000, #333); background: linear-gradient(#000, #333); -moz-border-radius: 5px; border-radius: 5px; /* outline:#000 solid thin; */ } #menu ul li { left:0; -moz-box-shadow: none; -webkit-box-shadow: none; box-shadow: none; } #menu ul a { padding: 10px; height: auto; line-height: 1; display: block; white-space: nowrap; float: none; text-transform: none; } *html #menu ul a /* IE6 */ { height: 10px; width: 200px; } *:first-child+html #menu ul a /* IE7 */ { height: 10px; width: 200px; } /*#menu ul a:hover { background: #000; background: -moz-linear-gradient(#000, #333); background: -webkit-gradient(linear, left top, left bottom, from(#04acec), to(#0186ba)); background: -webkit-linear-gradient(#000, #333); background: -o-linear-gradient(#000, #333); background: -ms-linear-gradient(#000, #333); background: linear-gradient(#000, #333); }*/ /* Clear floated elements */ #menu:after { visibility: hidden; display: block; font-size: 0; content: " "; clear: both; height: 0; } * html #menu { zoom: 1; } /* IE6 */ *:first-child+html #menu { zoom: 1; } /* IE7 */ CSS3 -Master Style Sheet- @charset "utf-8"; /* CSS Document */ a:link {color:#FC0; text-decoration:none;} /* unvisited link */ a:visited {color:#FC0; text-decoration:none;} /* visited link */ a:hover {color:#FFF; text-decoration:none;} /* mouse over link */ a:active {color:#FC0; text-decoration:none;} /* selected link */ ul.a {list-style-type:none;} ul.b {list-style-type:inherit} html { } body { /*background-image:url(images/cagebg.jpg);*/ background-repeat:repeat; background-position:top; } div.wrap { margin: 0 auto; min-height: 100%; position: relative; width: 1250px; } div.logo{ top:25px; left:20px; position:absolute; float:top; height:150px; } /*Freshman FONT is on my computer needs to be uploaded to the webhost and rendered host side like a webfont*/ div.header{ background-color:#999; color:#FC0; margin-left:5px; height:80px; width:1240px; line-height:70px; font-family:'freshman' cursive; font-size:50px; text-shadow:8px 8px #9c9c9c; text-outline:1px 1px #000; text-align:center; background-color:#999; clear: both; } div.social{ height:50px; margin-left:5px; width:1240px; font-family:'freshman' cursive; font-size:50px; text-align:right; color:#000; background-color:#999; line-height:30px; box-sizing: border-box; ms-box-sizing: border-box; webkit-box-sizing: border-box; moz-box-sizing: border-box; padding-right:5px; } div.mid{ position:absolute; min-height:100%; margin-left:5px; width:1240px; font-family:'freshman' cursive; font-size:50px; text-align:center; color:#000; background-color:#999; } /*SIDE left and right should be 40px wide and a minimum height (100% the area from nav-footer) to fill between the NAV and the footer yet stretch as displayed content streatches the page longer (scrollable)*/ div #side.sright{ top:96px; right:0; position:absolute; float:right; height:100%; min-height:100%; width:40px; background-image:url(images/border.png); } /*Container should vary in height in acordance to content displayed*/ div #content.container{ } /*Footer should stick at ABSOLUTE BOTTOM of the page*/ div #footer{ font-family:'freshman' cursive; position:fixed; bottom:0; background-color:#000000; margin-left:5px; width:1240px; color:#FC0; clear: both; /*this clear property forces the .container to understand where the columns end and contain them*/ } /*HTML 5 support - Sets new HTML 5 tags to display:block so browsers know how to render the tags properly.*/ header, section, footer, aside, nav, article, figure { display: block; } Eventually once the layout is correct I have to use PHP to make calls for where data should be displayed from what database. If anyone can help me to fix this layout and clean up the crap code, I'd be much appreciated.. I've spent weeks trying to figure this out.

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