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  • apache tomcat loadbalancing clustering on ubuntu

    - by user740010
    i am facing a problem in clustering the tomcat with apache as a loadbalancer using mod_jk on ubuntu. i have install apache2 on my ubuntu 11.04 and i have downloaded tomcat7 created two copies and kept them at two different location. 1st one is at /home/net4u/vishal/test/tomcatA 2nd one is at /home/net4u/vishal/test1/tomcatB i have made following changes to server.xml file in /conf folder 1. <Server port="8205" shutdown="SHUTDOWN"> 2. <Connector port="8280" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" /> 3.<Connector port="8209" protocol="AJP/1.3" redirectPort="8443" /> <Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcatB"> 4. <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/> similarly i have modified other tomcat i.e tomcatA server.xml content of the server.xml is as follow: -- <!--The connectors can use a shared executor, you can define one or more named thread pools--> <!-- <Executor name="tomcatThreadPool" namePrefix="catalina-exec-" maxThreads="150" minSpareThreads="4"/> --> <!-- A "Connector" represents an endpoint by which requests are received and responses are returned. Documentation at : Java HTTP Connector: /docs/config/http.html (blocking & non-blocking) Java AJP Connector: /docs/config/ajp.html APR (HTTP/AJP) Connector: /docs/apr.html Define a non-SSL HTTP/1.1 Connector on port 8080 --> <Connector port="8280" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" /> <!-- A "Connector" using the shared thread pool--> <!-- <Connector executor="tomcatThreadPool" port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" /> --> <!-- Define a SSL HTTP/1.1 Connector on port 8443 This connector uses the JSSE configuration, when using APR, the connector should be using the OpenSSL style configuration described in the APR documentation --> <!-- <Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true" maxThreads="150" scheme="https" secure="true" clientAuth="false" sslProtocol="TLS" /> --> <!-- Define an AJP 1.3 Connector on port 8009 --> <Connector port="8109" protocol="AJP/1.3" redirectPort="8443" /> <!-- An Engine represents the entry point (within Catalina) that processes every request. The Engine implementation for Tomcat stand alone analyzes the HTTP headers included with the request, and passes them on to the appropriate Host (virtual host). Documentation at /docs/config/engine.html --> <!-- You should set jvmRoute to support load-balancing via AJP ie : <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1"> --> <Engine name="Catalina" defaultHost="localhost" jvmRoute="tomcatB"> <!--For clustering, please take a look at documentation at: /docs/cluster-howto.html (simple how to) /docs/config/cluster.html (reference documentation) --> <!-- uncomment for clustering--> <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/> <!-- Use the LockOutRealm to prevent attempts to guess user passwords via a brute-force attack --> <Realm className="org.apache.catalina.realm.LockOutRealm"> <!-- This Realm uses the UserDatabase configured in the global JNDI resources under the key "UserDatabase". Any edits that are performed against this UserDatabase are immediately available for use by the Realm. --> <Realm className="org.apache.catalina.realm.UserDatabaseRealm" resourceName="UserDatabase"/> </Realm> <Host name="localhost" appBase="webapps" unpackWARs="true" autoDeploy="true"> <!-- SingleSignOn valve, share authentication between web applications Documentation at: /docs/config/valve.html --> <!-- <Valve className="org.apache.catalina.authenticator.SingleSignOn" /> --> <!-- Access log processes all example. Documentation at: /docs/config/valve.html Note: The pattern used is equivalent to using pattern="common" --> <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs" prefix="localhost_access_log." suffix=".txt" pattern="%h %l %u %t &quot;%r&quot; %s %b" resolveHosts="false"/> </Host> </Engine> i have install libapache2-mod-jk step 1. i have Created jk.load file in /etc/apache2/mods-enabled/jk.load content is as follows: LoadModule jk_module /usr/lib/apache2/modules/mod_jk.so Create /etc/apache2/mods-enabled/jk.conf: JkWorkersFile /etc/apache2/workers.properties JkLogFile /var/log/apache2/jk.log JkMount /ecommerce/* worker1 JkMount /images/* worker1 JkMount /content/* worker1 step 2. Created workers.properties file in /etc/apache2/workers.properties content is as follows: workers.tomcat_home=/home/vishal/Desktop/test/tomcatA workers.java_home=/usr/lib/jvm/default-java ps=/ worker.list=tomcatA,tomcatB,loadbalancer   worker.tomcatA.port=8109 worker.tomcatA.host=localhost worker.tomcatA.type=ajp13 worker.tomcatA.lbfactor=1   worker.tomcatB.port=8209 worker.tomcatB.host=localhost worker.tomcatB.type=ajp13 worker.tomcatB.lbfactor=1 worker.loadbalancer.type=lb worker.loadbalancer.balanced_workers=tomcatA,tomcatB worker.loadbalancer.sticky_session=1 i tried the same thing on the windows machine it is working.

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  • ADO.NET (WCF) Data Services Query Interceptor Hangs IIS

    - by PreMagination
    I have an ADO.NET Data Service that's supposed to provide read-only access to a somewhat complex database. Logically I have table-per-type (TPT) inheritance in my data model but the EDM doesn't implement inheritance. (Limitation of EF and navigation properties on derived types. STILL not fixed in EF4!) I can query my EDM directly (using a separate project) using a copy of the query I'm trying to run against the web service, results are returned within 10 seconds. Disabling the query interceptors I'm able to make the same query against the web service, results are returned similarly quickly. I can enable some of the query interceptors and the results are returned slowly, up to a minute or so later. Alternatively, I can enable all the query interceptors, expand less of the properties on the main object I'm querying, and results are returned in a similar period of time. (I've increased some of the timeout periods) Up til this point Sql Profiler indicates the slow-down is the database. (That's a post for a different day) But when I enable all my query interceptors and expand all the properties I'd like to have the IIS worker process pegs the CPU for 20 minutes and a query is never even made against the database. This implies to me that yes, my implementation probably sucks but regardless the Data Services "tier" is having an issue it shouldn't. WCF tracing didn't reveal anything interesting to my untrained eye. Details: Data model: Agent-Person-Student Student has a collection of referrals Students and referrals are private, queries against the web service should only return "your" students and referrals. This means Person and Agent need to be filtered too. Other entities (Agent-Organization-School) can be accessed by anyone who has authenticated. The existing security model is poorly suited to perform this type of filtering for this type of data access, the query interceptors are complicated and cause EF to generate some entertaining sql queries. Sample Interceptor [QueryInterceptor("Agents")] public Expression<Func<Agent, Boolean>> OnQueryAgents() { //Agent is a Person(1), Educator(2), Student(3), or Other Person(13); allow if scope permissions exist return ag => (ag.AgentType.AgentTypeId == 1 || ag.AgentType.AgentTypeId == 2 || ag.AgentType.AgentTypeId == 3 || ag.AgentType.AgentTypeId == 13) && ag.Person.OrganizationPersons.Count<OrganizationPerson>(op => op.Organization.ScopePermissions.Any<ScopePermission> (p => p.ApplicationRoleAccount.Account.UserName == HttpContext.Current.User.Identity.Name && p.ApplicationRoleAccount.Application.ApplicationId == 124) || op.Organization.HierarchyDescendents.Any<OrganizationsHierarchy>(oh => oh.AncestorOrganization.ScopePermissions.Any<ScopePermission> (p => p.ApplicationRoleAccount.Account.UserName == HttpContext.Current.User.Identity.Name && p.ApplicationRoleAccount.Application.ApplicationId == 124))) > 0; } The query interceptors for Person, Student, Referral are all very similar, ie they traverse multiple same/similar tables to look for ScopePermissions as above. Sample Query var referrals = (from r in service.Referrals .Expand("Organization/ParentOrganization") .Expand("Educator/Person/Agent") .Expand("Student/Person/Agent") .Expand("Student") .Expand("Grade") .Expand("ProblemBehavior") .Expand("Location") .Expand("Motivation") .Expand("AdminDecision") .Expand("OthersInvolved") where r.DateCreated >= coupledays && r.DateDeleted == null select r); Any suggestions or tips would be greatly associated, for fixing my current implementation or in developing a new one, with the caveat that the database can't be changed and that ultimately I need to expose a large portion of the database via a web service that limits data access to the data authorized for, for the purpose of data integration with multiple outside parties. THANK YOU!!!

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  • javamail error :must issue starttls command first

    - by bobby
    im trying to send a mail using javamail api using the below code:when i compiled the class file im getting the below error which says 'must issue starttls command first' i have mentioned the error below. and also getProvider() function error i think so...i dont know what the errors mean. import javax.servlet.*; import javax.servlet.http.*; import java.io.*; import javax.mail.*; import javax.mail.internet.*; import javax.mail.event.*; import javax.mail.Authenticator; import java.net.*; import java.util.Properties; public class mailexample { public static void main (String args[]) throws Exception { String from = args[0]; String to = args[1]; try { Properties props=new Properties(); props.put("mail.transport.protocol", "smtp"); props.put("mail.smtp.host","smtp.gmail.com"); props.put("mail.smtp.port", "25"); props.put("mail.smtp.auth", "true"); javax.mail.Authenticator authenticator = new javax.mail.Authenticator() { protected javax.mail.PasswordAuthentication getPasswordAuthentication() { return new javax.mail.PasswordAuthentication("[email protected]", "pass"); } }; Session sess=Session.getDefaultInstance(props,authenticator); sess.setDebug (true); Transport transport =sess.getTransport ("smtp"); Message msg=new MimeMessage(sess); msg.setFrom(new InternetAddress(from)); msg.addRecipient(Message.RecipientType.TO, new InternetAddress(to)); msg.setSubject("Hello JavaMail"); msg.setText("Welcome to JavaMail"); transport.connect(); transport.send(msg); } catch(Exception e) { System.out.println("err"+e); } } } error: C:\Users\bobby\Desktopjava mailexample [email protected] abc@gmail. com DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.s mtp.SMTPTransport,Sun Microsystems, Inc] DEBUG SMTP: useEhlo true, useAuth true DEBUG SMTP: useEhlo true, useAuth true DEBUG: SMTPTransport trying to connect to host "smtp.gmail.com", port 25 DEBUG SMTP RCVD: 220 mx.google.com ESMTP q10sm12956046rvp.20 DEBUG: SMTPTransport connected to host "smtp.gmail.com", port: 25 DEBUG SMTP SENT: EHLO bobby-PC DEBUG SMTP RCVD: 250-mx.google.com at your service, [60.243.184.29] 250-SIZE 35651584 250-8BITMIME 250-STARTTLS 250 ENHANCEDSTATUSCODES DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.s mtp.SMTPTransport,Sun Microsystems, Inc] DEBUG SMTP: useEhlo true, useAuth true DEBUG SMTP: useEhlo true, useAuth true DEBUG: SMTPTransport trying to connect to host "smtp.gmail.com", port 25 DEBUG SMTP RCVD: 220 mx.google.com ESMTP l29sm12930755rvb.16 DEBUG: SMTPTransport connected to host "smtp.gmail.com", port: 25 DEBUG SMTP SENT: EHLO bobby-PC DEBUG SMTP RCVD: 250-mx.google.com at your service, [60.243.184.29] 250-SIZE 35651584 250-8BITMIME 250-STARTTLS 250 ENHANCEDSTATUSCODES DEBUG SMTP SENT: MAIL FROM: DEBUG SMTP RCVD: 530 5.7.0 Must issue a STARTTLS command first. l29sm12930755rvb .16 DEBUG SMTP SENT: QUIT errjavax.mail.SendFailedException: Sending failed; nested exception is: javax.mail.MessagingException: 530 5.7.0 Must issue a STARTTLS command f irst. l29sm12930755rvb.16

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  • Ejb 2.0 deployment issues on Jboss 5.1

    - by Ravi
    I am deploying an ear application on Jboss 5.1.0. and i facing some issues. I had two ears one i had copied to deploy folder and the other in deploy-hasingleton. The ear which is in deploy-hasingleton is throwing some errors.when i serached in google i came to know that there is some issue with EJB 2.x on jboss 5.1.i was not able to find the solution. Below is the log. profileservice-secured.jar 11:16:17,162 INFO [JBossASKernel] installing bean: jboss.j2ee:jar=profileservice-secured.jar,name=SecureManagementView,service=EJB3 11:16:17,162 INFO [JBossASKernel] with dependencies: 11:16:17,162 INFO [JBossASKernel] and demands: 11:16:17,162 INFO [JBossASKernel] jboss.ejb:service=EJBTimerService 11:16:17,162 INFO [JBossASKernel] and supplies: 11:16:17,162 INFO [JBossASKernel] jndi:SecureManagementView/remote-org.jboss.deployers.spi.management.ManagementView 11:16:17,162 INFO [JBossASKernel] Class:org.jboss.deployers.spi.management.ManagementView 11:16:17,162 INFO [JBossASKernel] jndi:SecureManagementView/remote 11:16:17,162 INFO [JBossASKernel] Added bean(jboss.j2ee:jar=profileservice-secured.jar,name=SecureManagementView,service=EJB3) to KernelDeployment of: profileservice-secured.jar 11:16:17,162 INFO [EJB3EndpointDeployer] Deploy AbstractBeanMetaData@17cabbb{name=jboss.j2ee:jar=profileservice-secured.jar,name=SecureProfileService,service=EJB3_endpoint bean=org.jboss.ejb3.endpoint.deployers.impl.EndpointImpl properties=[container] constructor=null autowireCandidate=true} 11:16:17,162 INFO [EJB3EndpointDeployer] Deploy AbstractBeanMetaData@1fedd5c{name=jboss.j2ee:jar=profileservice-secured.jar,name=SecureDeploymentManager,service=EJB3_endpoint bean=org.jboss.ejb3.endpoint.deployers.impl.EndpointImpl properties=[container] constructor=null autowireCandidate=true} 11:16:17,162 INFO [EJB3EndpointDeployer] Deploy AbstractBeanMetaData@1ef4b31{name=jboss.j2ee:jar=profileservice-secured.jar,name=SecureManagementView,service=EJB3_endpoint bean=org.jboss.ejb3.endpoint.deployers.impl.EndpointImpl properties=[container] constructor=null autowireCandidate=true} 11:16:17,833 INFO [SessionSpecContainer] Starting jboss.j2ee:jar=profileservice-secured.jar,name=SecureDeploymentManager,service=EJB3 11:16:17,833 INFO [EJBContainer] STARTED EJB: org.jboss.profileservice.ejb.SecureDeploymentManager ejbName: SecureDeploymentManager 11:16:18,066 INFO [JndiSessionRegistrarBase] Binding the following Entries in Global JNDI: SecureDeploymentManager/remote - EJB3.x Default Remote Business Interface SecureDeploymentManager/remote-org.jboss.deployers.spi.management.deploy.DeploymentManager - EJB3.x Remote Business Interface 11:16:18,129 INFO [SessionSpecContainer] Starting jboss.j2ee:jar=profileservice-secured.jar,name=SecureManagementView,service=EJB3 11:16:18,129 INFO [EJBContainer] STARTED EJB: org.jboss.profileservice.ejb.SecureManagementView ejbName: SecureManagementView 11:16:18,160 INFO [JndiSessionRegistrarBase] Binding the following Entries in Global JNDI: SecureManagementView/remote - EJB3.x Default Remote Business Interface SecureManagementView/remote-org.jboss.deployers.spi.management.ManagementView - EJB3.x Remote Business Interface 11:16:18,206 INFO [SessionSpecContainer] Starting jboss.j2ee:jar=profileservice-secured.jar,name=SecureProfileService,service=EJB3 11:16:18,206 INFO [EJBContainer] STARTED EJB: org.jboss.profileservice.ejb.SecureProfileServiceBean ejbName: SecureProfileService 11:16:18,238 INFO [JndiSessionRegistrarBase] Binding the following Entries in Global JNDI: SecureProfileService/remote - EJB3.x Default Remote Business Interface SecureProfileService/remote-org.jboss.profileservice.spi.ProfileService - EJB3.x Remote Business Interface 11:16:18,534 INFO [TomcatDeployment] deploy, ctxPath=/admin-console 11:16:18,612 INFO [config] Initializing Mojarra (1.2_12-b01-FCS) for context '/admin-console' 11:16:21,759 INFO [TomcatDeployment] deploy, ctxPath=/ 11:16:21,853 INFO [TomcatDeployment] deploy, ctxPath=/jmx-console 11:16:21,993 INFO [JBossASKernel] Created KernelDeployment for: hapi-0.5.jar 11:16:21,993 INFO [JBossASKernel] installing bean: jboss.j2ee:ear=jca-ear-1.3-SNAPSHOT.ear,jar=hapi-0.5.jar,name=hapi-0.5,service=EJB3 11:16:21,993 INFO [JBossASKernel] with dependencies: 11:16:21,993 INFO [JBossASKernel] and demands: 11:16:21,993 INFO [JBossASKernel] and supplies: 11:16:21,993 INFO [JBossASKernel] Added bean(jboss.j2ee:ear=jca-ear-1.3-SNAPSHOT.ear,jar=hapi-0.5.jar,name=hapi-0.5,service=EJB3) to KernelDeployment of: hapi-0.5.jar 11:16:23,302 INFO [ClientENCInjectionContainer] STARTED CLIENT ENC CONTAINER: hapi-0.5 11:16:23,473 INFO [SystemEventService] NODE_STARTED on node [HCA-5C1P1BS] 11:16:23,489 INFO [AbstractConnector] [aware] connector started 11:16:23,536 INFO [AbstractConnector] [datacaptor] connector started 11:16:23,536 INFO [AbstractConnector] [intellivue] connector started 11:16:23,972 ERROR [ProfileServiceBootstrap] Failed to load profile: Summary of incomplete deployments (SEE PREVIOUS ERRORS FOR DETAILS): DEPLOYMENTS MISSING DEPENDENCIES: Deployment "gehc.com:service=KernelServiceMBean" is missing the following dependencies: Dependency "jboss.j2ee:module=kernel-ejb-1.3-SNAPSHOT.jar,service=EjbModule" (should be in state "Create", but is actually in state " NOT FOUND Depends on 'jboss.j2ee:module=kernel-ejb-1.3-SNAPSHOT.jar,service=EjbModule' ") Deployment "jboss.j2ee:module="kernel-ejb-1.3-SNAPSHOT.jar",service=EjbModule" is missing the following dependencies: Dependency "gehc.com:service=KernelServiceMBean" (should be in state "Create", but is actually in state "Configured") DEPLOYMENTS IN ERROR: Deployment "jboss.j2ee:module=kernel-ejb-1.3-SNAPSHOT.jar,service=EjbModule" is in error due to the following reason(s): ** NOT FOUND Depends on 'jboss.j2ee:module=kernel-ejb-1.3-SNAPSHOT.jar,service=EjbModule' ** 11:16:24,003 INFO [Http11Protocol] Starting Coyote HTTP/1.1 on http-127.0.0.1-8080 11:16:24,034 INFO [AjpProtocol] Starting Coyote AJP/1.3 on ajp-127.0.0.1-8009 11:16:24,050 INFO [ServerImpl] JBoss (Microcontainer) [5.1.0.GA (build: SVNTag=JBoss_5_1_0_GA date=200905221053)] Started in 1m:49s:575ms I had marked the error with bold, there is some circular dependency also. Thanks Ravi S

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  • How to "DRY up" C# attributes in Models and ViewModels?

    - by DanM
    This question was inspired by my struggles with ASP.NET MVC, but I think it applies to other situations as well. Let's say I have an ORM-generated Model and two ViewModels (one for a "details" view and one for an "edit" view): Model public class FooModel // ORM generated { public int Id { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public string EmailAddress { get; set; } public int Age { get; set; } public int CategoryId { get; set; } } Display ViewModel public class FooDisplayViewModel // use for "details" view { [DisplayName("ID Number")] public int Id { get; set; } [DisplayName("First Name")] public string FirstName { get; set; } [DisplayName("Last Name")] public string LastName { get; set; } [DisplayName("Email Address")] [DataType("EmailAddress")] public string EmailAddress { get; set; } public int Age { get; set; } [DisplayName("Category")] public string CategoryName { get; set; } } Edit ViewModel public class FooEditViewModel // use for "edit" view { [DisplayName("First Name")] // not DRY public string FirstName { get; set; } [DisplayName("Last Name")] // not DRY public string LastName { get; set; } [DisplayName("Email Address")] // not DRY [DataType("EmailAddress")] // not DRY public string EmailAddress { get; set; } public int Age { get; set; } [DisplayName("Category")] // not DRY public SelectList Categories { get; set; } } Note that the attributes on the ViewModels are not DRY--a lot of information is repeated. Now imagine this scenario multiplied by 10 or 100, and you can see that it can quickly become quite tedious and error prone to ensure consistency across ViewModels (and therefore across Views). How can I "DRY up" this code? Before you answer, "Just put all the attributes on FooModel," I've tried that, but it didn't work because I need to keep my ViewModels "flat". In other words, I can't just compose each ViewModel with a Model--I need my ViewModel to have only the properties (and attributes) that should be consumed by the View, and the View can't burrow into sub-properties to get at the values. Update LukLed's answer suggests using inheritance. This definitely reduces the amount of non-DRY code, but it doesn't eliminate it. Note that, in my example above, the DisplayName attribute for the Category property would need to be written twice because the data type of the property is different between the display and edit ViewModels. This isn't going to be a big deal on a small scale, but as the size and complexity of a project scales up (imagine a lot more properties, more attributes per property, more views per model), there is still the potentially for "repeating yourself" a fair amount. Perhaps I'm taking DRY too far here, but I'd still rather have all my "friendly names", data types, validation rules, etc. typed out only once.

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  • handle null values for string when implementing IXmlSerializable interface

    - by user208081
    I have the following class that implements IXmlSerializable. When implementing WriteXml(), I need to handle the case where the string members of this class may be null values. What is the best way of handling this? Currently, I am using the default constructor in which all the string properties are initialized to empty string values. This way, when WriteXml() is called, the string will not be null. One other way I could do this is check using String.IsNullOrEmpty before writing each string in xml. Any suggestions on how I can improve this code? using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Xml.Serialization; using System.Globalization; namespace TCS.Common.InformationObjects { public sealed class FaxSender : IXmlSerializable { #region Public Constants private const string DEFAULT_CLASS_NAME = "FaxSender"; #endregion Public Constants #region Public Properties public string Name { get; set; } public string Organization { get; set; } public string PhoneNumber { get; set; } public string FaxNumber { get; set; } public string EmailAddress { get; set; } #endregion Public Properties #region Public Methods #region Constructors public FaxSender() { Name = String.Empty; Organization = String.Empty; PhoneNumber = String.Empty; FaxNumber = String.Empty; EmailAddress = String.Empty; } public FaxSender(string name, string organization, string phoneNumber, string faxNumber, string emailAddress) { Name = name; Organization = organization; PhoneNumber = phoneNumber; FaxNumber = faxNumber; EmailAddress = emailAddress; } #endregion Constructors #region IXmlSerializable Members public System.Xml.Schema.XmlSchema GetSchema() { throw new NotImplementedException(); } public void ReadXml(System.Xml.XmlReader reader) { throw new NotImplementedException(); } public void WriteXml(System.Xml.XmlWriter xmlWriter) { try { // <sender> xmlWriter.WriteStartElement("sender"); // Write the name of the sender as an element. xmlWriter.WriteElementString("name", this.Name.ToString(CultureInfo.CurrentCulture)); // Write the organization of the sender as an element. xmlWriter.WriteElementString("organization", this.Organization.ToString(CultureInfo.CurrentCulture)); // Write the phone number of the sender as an element. xmlWriter.WriteElementString("phone_number", this.PhoneNumber.ToString(CultureInfo.CurrentCulture)); // Write the fax number of the sender as an element. xmlWriter.WriteElementString("fax_number", this.FaxNumber.ToString(CultureInfo.CurrentCulture)); // Write the email address of the sender as an element. xmlWriter.WriteElementString("email_address", this.EmailAddress.ToString(CultureInfo.CurrentCulture)); // </sender> xmlWriter.WriteEndElement(); } catch { // Rethrow any exceptions. throw; } } #endregion IXmlSerializable Members #endregion Public Methods } }

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  • An "elegant" way of identifying a field?

    - by Alix
    Hi. I'm writing a system that underlies programmer applications and that needs to detect their access to certain data. I can mostly do so with properties, like this: public class NiceClass { public int x { get; set; } } Then I go in and tweak the get and set accessors so that they handle the accesses appropriately. However this requires that the users (application programmers) define all of their data as properties. If the users want to use pre-existing classes that have "normal" fields (as opposed to properties), I cannot detect those accesses. Example: public class NotSoNiceClass { public int y; } I cannot detect accesses to y. However, I want to allow the use of pre-existing classes. As a compromise the users are responsible for notifying me whenever an access to that kind of data occurs. For example: NotSoNiceClass notSoNice; ... Write(notSoNice.y, 0); // (as opposed to notSoNice.y = 0;) Something like that. Believe me, I've researched this very thoroughly and even directly analysing the bytecode to detect accesses isn't reliable due to possible indirections, etc. I really do need the users to notify me. And now my question: could you recommend an "elegant" way to perform these notifications? (Yes, I know this whole situation isn't "elegant" to begin with; I'm trying not to make it worse ;) ). How would you do it? This is a problem for me because actually the situation is like this: I have the following class: public class SemiNiceClass { public NotSoNiceClass notSoNice { get; set; } public int z { get; set; } } If the user wants to do this: SemiNiceClass semiNice; ... semiNice.notSoNice.y = 0; They must instead do something like this: semiNice.Write("notSoNice").y = 0; Where Write will return a clone of notSoNice, which is what I wanted the set accessor to do anyway. However, using a string is pretty ugly: if later they refactor the field they'll have to go over their Write("notSoNice") accesses and change the string. How can we identify the field? I can only think of strings, ints and enums (i.e., ints again). But: We've already discussed the problem with strings. Ints are a pain. They're even worse because the user needs to remember which int corresponds to which field. Refactoring is equally difficult. Enums (such as NOT_SO_NICE and Z, i.e., the fields of SemiNiceClass) ease refactoring, but they require the user to write an enum per class (SemiNiceClass, etc), with a value per field of the class. It's annoying. I don't want them to hate me ;) So why, I hear you ask, can we not do this (below)? semiNice.Write(semiNice.notSoNice).y = 0; Because I need to know what field is being accessed, and semiNice.notSoNice doesn't identify a field. It's the value of the field, not the field itself. Sigh. I know this is ugly. Believe me ;) I'll greatly appreciate suggestions. Thanks in advance! (Also, I couldn't come up with good tags for this question. Please let me know if you have better ideas, and I'll edit them)

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  • JavaMail - javax.mail.MessagingException

    - by legendofawesomeness
    I am trying to write a simple mail sender class that would receive a bunch of arguments and using those will send an email out using our Exchange 2010 server. While authentication etc. seem to work fine, I am getting the following exception when the code is actually trying to send the email (I think). I have ensured that the authentication is working and I get a transport back from the session, but still it fails. Could anyone shed some like on what I am doing wrong or missing? Thanks. Exception: javax.mail.MessagingException: [EOF] at com.sun.mail.smtp.SMTPTransport.issueCommand(SMTPTransport.java:1481) at com.sun.mail.smtp.SMTPTransport.issueSendCommand(SMTPTransport.java:1512) at com.sun.mail.smtp.SMTPTransport.mailFrom(SMTPTransport.java:1054) at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:634) at javax.mail.Transport.send0(Transport.java:189) at javax.mail.Transport.send(Transport.java:140) at com.ri.common.mail.util.MailSender.sendHTMLEmail(MailSender.java:75) at com.ri.common.mail.util.MailSender.main(MailSender.java:106) Relevant code: import java.util.Properties; import javax.mail.Authenticator; import javax.mail.Message; import javax.mail.MessagingException; import javax.mail.PasswordAuthentication; import javax.mail.Session; import javax.mail.Transport; import javax.mail.internet.InternetAddress; import javax.mail.internet.MimeMessage; public class MailSender { public static void sendHTMLEmail( String fromEmailId, String toEmailId, String host, String hostUserName, String hostPassword, String mailSubject, String mailBody ) { // Get system properties. Properties props = System.getProperties(); // Setup mail server props.put( "mail.transport.protocol", "smtp" ); props.put( "mail.smtp.host", host ); props.put( "mail.smtp.auth", "true" ); final String hostUName = hostUserName; final String hPassword = hostPassword; Authenticator authenticator = new Authenticator() { protected PasswordAuthentication getPasswordAuthentication() { return new PasswordAuthentication( hostUName, hPassword ); } }; // Get the default Session object. Session session = Session.getDefaultInstance( props, authenticator ); try { // Create a default MimeMessage object. MimeMessage message = new MimeMessage( session ); // Set From: header field of the header. message.setFrom( new InternetAddress( fromEmailId ) ); // Set To: header field of the header. message.addRecipient( Message.RecipientType.TO, new InternetAddress( toEmailId ) ); // Set Subject: header field message.setSubject( mailSubject ); // Send the actual HTML message, as big as you like message.setContent( mailBody, "text/html" ); // Send message Transport.send( message, message.getAllRecipients() ); System.out.println( "Sent message successfully...." ); } catch( Exception mex ) { mex.printStackTrace(); } } public static void main( String[] args ) { String to = "[email protected]"; String from = "[email protected]"; String host = "correctHostForExch2010"; String user = "correctUser"; String password = "CorrectPassword"; String subject = "Test Email"; String body = "Hi there. This is a test email!"; MailSender.sendHTMLEmail( from, to, host, user, password, subject, body ); } } EDIT: I turned on debugging and it says MAIL FROM:<[email protected]> 530 5.7.1 Client was not authenticated DEBUG SMTP: got response code 530, with response: 530 5.7.1 Client was not authenticated. Why would that be when the session authentication succeded?

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  • iPhone dev - viewDidUnload subviews

    - by Mk12
    I'm having a hard time undestand a couple of the methods in UIViewController, but first I'll say what I think they are meant for (ignoring interface builder because I'm not using it): -init: initialize non view-related stuff that won't need to be released in low memory situations (i.e. not objects or objects that can't be recreated easily). -loadView: create the view set the [self view] property. -viewDidLoad: Create all the other view elements -viewDidUnload: Release objects created in -viewDidLoad. didReceiveMemoryWarning: Low-memory situation, release unnecessary things such as cached data, if this view doesn't have a superview then the [super didReceiveMemoryWarning] will go on to release (unload) the view and call -viewDidUnload. -dealloc: release everything -viewWillAppear:, -viewDidAppear:, -viewWillDisappear:, -viewDidDisappear: self-explanatory, not necessary unless you want to respond (do something) to those events. I'm not sure about a couple of things. First, the Apple docs say that when -viewDidUnload is called, the view has already been released and set to nil. Will -loadView get called again to recreate the view later on? There's a few things I created in -viewDidLoad that I didn't make a ivar/property for because there is no need and it will be retained by the view (because they are subviews of it). So when the view is released, it will release those too, right? When the view is released, will it release all its subviews? Because all the objects I created in -viewDidLoad are subviews of [self view]. So if they already get released why release them again in -viewDidUnload? I can understand data that is necessary when the view is visible being loaded and unloaded in these methods, but like I asked, why release the subviews if they already get released? EDIT: After reading other questions, I think I might have got it (my 2nd question). In the situation where I just use a local variable, alloc it, make it a subview and release, it will have a retain count of 1 (from adding it as a subview), so when the view is released it is too. Now for the view elements with ivars pointing to them, I wasn't using properties because no outside class would need to access them. But now I think that that's wrong, because in this situation: // MyViewController.h @interface MyViewController : UIViewController { UILabel *myLabel; } // MyViewController.m . . . - (void)viewDidLoad { myLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 40, 10)]; [myLabel setText:@"Foobar"]; [[self view] addSubview:myLabel]; } - (void)viewDidUnload [ // equivalent of [self setMyLabel:nil]; without properties [myLabel release]; myLabel = nil; } In that situation, the label will be sent the -release message after it was deallocated because the ivar didn't retain it (because it wasn't a property). But with a property the retain count would be two: the view retaining it and the property. So then in -viewDidUnload it will get deallocated. So its best to just always use properties for these things, am I right? Or not? EDIT: I read somewhere that -viewDidLoad and -viewDidUnload are only for use with Interface Builder, that if you are doing everything programmatically you shouldn't use them. Is that right? Why?

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  • Corrupt mercurial repository - cannot update

    - by richzilla
    Hi all, i think ive managed to corrupt one of mercurial repositories, is there anyway to recover the damage? the message i get when attempting to update the repo to my default branch is: PS C:\wco\projects\ims\code> hg up -C default abort: data/Trunk/application/models/priority_model.php.i@83dbdfb60981: no match found! when i run hg verify, i get the following report: PS C:\wco\projects\ims\code> hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files data/.buildpath.i@0: missing revlog! 0: empty or missing .buildpath .buildpath@0: daf15acb5273 in manifests not found data/.project.i@0: missing revlog! 0: empty or missing .project .project@0: e8b25997d6d1 in manifests not found Rawlings IMS/index.html@3: empty or missing copy source revlog index.html:b8b2b36a6eea Rawlings IMS/index.php@3: empty or missing copy source revlog index.php:a5f76bf232e9 Rawlings IMS/index_backup.php@3: empty or missing copy source revlog index_backup.php:a5f76bf232e9 Rawlings IMS/index_this_hold.html@3: empty or missing copy source revlog index_this_hold.html:b8b2b36a6eea Rawlings IMS/testera.php@3: empty or missing copy source revlog testera.php:6e9e3666c1bc Trunk/application/models/priority_model.php@32: 83dbdfb60981 in manifests not found data/index.html.i@0: missing revlog! 0: empty or missing index.html index.html@0: b8b2b36a6eea in manifests not found data/index.php.i@0: missing revlog! 0: empty or missing index.php index.php@0: a5f76bf232e9 in manifests not found data/index_backup.php.i@0: missing revlog! 0: empty or missing index_backup.php index_backup.php@0: a5f76bf232e9 in manifests not found data/index_this_hold.html.i@0: missing revlog! 0: empty or missing index_this_hold.html index_this_hold.html@0: b8b2b36a6eea in manifests not found data/nbproject/project.properties.i@14: missing revlog! 14: empty or missing nbproject/project.properties nbproject/project.properties@14: 1efa3074378b in manifests not found data/nbproject/project.xml.i@14: missing revlog! 14: empty or missing nbproject/project.xml nbproject/project.xml@14: 52689bf2b35a in manifests not found data/rcrawley/.buildpath.i@9: missing revlog! 9: empty or missing rcrawley/.buildpath rcrawley/.buildpath@9: 2c6411d4fcff in manifests not found data/rcrawley/.project.i@9: missing revlog! 9: empty or missing rcrawley/.project rcrawley/.project@9: cb4b1495acab in manifests not found data/rcrawley/assets/images/ajax-loader.gif.i@9: missing revlog! 9: empty or missing rcrawley/assets/images/ajax-loader.gif rcrawley/assets/images/ajax-loader.gif@9: 8ef26516c7da in manifests not found data/rcrawley/index.html.i@9: missing revlog! 9: empty or missing rcrawley/index.html rcrawley/index.html@9: 545246299dee in manifests not found data/rcrawley/index.php.i@9: missing revlog! 9: empty or missing rcrawley/index.php rcrawley/index.php@9: 66eac798ed6d in manifests not found data/rcrawley/index_backup.php.i@9: missing revlog! 9: empty or missing rcrawley/index_backup.php rcrawley/index_backup.php@9: 93971228fbf5 in manifests not found data/rcrawley/system/index.html.i@9: missing revlog! 9: empty or missing rcrawley/system/index.html rcrawley/system/index.html@9: 17360d3b566e in manifests not found data/rcrawley/testera.php.i@9: missing revlog! 9: empty or missing rcrawley/testera.php rcrawley/testera.php@9: 7d9bd5196740 in manifests not found data/testera.php.i@0: missing revlog! 0: empty or missing testera.php testera.php@0: 6e9e3666c1bc in manifests not found 1646 files, 59 changesets, 1897 total revisions 57 integrity errors encountered! (first damaged changeset appears to be 0) since the first damaged changeset is 0, this would appear to be pretty terminal. Is there anyway around this? any help would be appreciated.

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  • Problems with maven output directory

    - by Gandalf StormCrow
    I'm using almost same POM for both my projects, they are on the same workspace but they are not related at all, they are related however because in both I use spring and jboss. Here is the pom : <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.springinaction.hello</groupId> <artifactId>spring-in-action</artifactId> <packaging>jar</packaging> <version>0.0.1-SNAPSHOT</version> <name>spring-in-action</name> <url>http://maven.apache.org</url> <properties> <jboss.ome>C:\jboss-5.1.0.GA\server\default\deploy</jboss.ome> <springversion>2.5.3</springversion> </properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring</artifactId> <version>${springversion}</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.14</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>2.0</version> <configuration> <warName>spring-book</warName> <outputDirectory>${jboss.ome}</outputDirectory> </configuration> </plugin> </plugins> </build> </project> What I want to achieve with this POM is that I want to name my war when built spring-book.war and copy it to Jboss location I specified. Now in my first project this works it does exactly what I requested but in other it does not. I changed springversion and jboss home properties variable but everything remains the same, what can I do ? The project builds and all, everything is working perfectly just I don't want to copy everytime in my jboss dir and previously remove the old war, it takes about 20sec on each source code change its a lot

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  • ADO program to list members of a large group.

    - by AlexGomez
    Hi everyone, I'm attempting to list all the members in a Active Directory group using ADO. The problem I have is that many of these groups have over 1500 members and ADSI cannot handle more than 1500 items in a multi-valued attribute. Fortunately I came across Richard Muller's wonderful VBScript that handles more than 1500 members at http://www.rlmueller.net/DocumentLargeGroup.htm I modified his code as shown below so that I can list ALL the groups and its memberships in a certain OU. However, I'm keeping getting the exception shown below: "ADODB.Recordset: Item cannot be found in the collection corresponding to the requested name or ordinal." My program appears to get stuck at: strPath = adoRecordset.Fields("ADsPath").Value Set objGroup = GetObject(strPath) All I am doing above is issuing the query to get back a recordset consisting of the ADsPath for each group in the OU. It then walks through the recordset and grabs the ADsPath for the first group and store its in a variable named strPath; we then use the value of that variable to bind to the group account for that group. It really should work! Any idea why the code below doesn't work for me? Any pointers will be great appreciated. Thanks. Option Explicit Dim objRootDSE, strDNSDomain, adoCommand Dim adoConnection, strBase, strAttributes Dim strFilter, strQuery, adoRecordset Dim strDN, intCount, blnLast, intLowRange Dim intHighRange, intRangeStep, objField Dim objGroup, objMember, strName ' Determine DNS domain name. Set objRootDSE = GetObject("LDAP://RootDSE") 'strDNSDomain = objRootDSE.Get("DefaultNamingContext") strDNSDomain = "XXXXXXXX" ' Use ADO to search Active Directory. Set adoCommand = CreateObject("ADODB.Command") Set adoConnection = CreateObject("ADODB.Connection") adoConnection.Provider = "ADsDSOObject" adoConnection.Open = "Active Directory Provider" adoCommand.ActiveConnection = adoConnection adoCommand.Properties("Page Size") = 100 adoCommand.Properties("Timeout") = 30 adoCommand.Properties("Cache Results") = False ' Specify base of search. strBase = "<LDAP://" & strDNSDomain & ">" ' Specify the attribute values to retrieve. strAttributes = "member" ' Filter on objects of class "group" strFilter = "(&(objectClass=group)(samAccountName=*))" ' Enumerate direct group members. ' Use range limits to handle more than 1000/1500 members. ' Setup to retrieve 1000 members at a time. blnLast = False intRangeStep = 999 intLowRange = 0 IntHighRange = intLowRange + intRangeStep Do While True If (blnLast = True) Then ' If last query, retrieve remaining members. strQuery = strBase & ";" & strFilter & ";" _ & strAttributes & ";range=" & intLowRange _ & "-*;subtree" Else ' If not last query, retrieve 1000 members. strQuery = strBase & ";" & strFilter & ";" _ & strAttributes & ";range=" & intLowRange & "-" _ & intHighRange & ";subtree" End If adoCommand.CommandText = strQuery Set adoRecordset = adoCommand.Execute adoRecordset.MoveFirst intCount = 0 Do Until adoRecordset.EOF strPath = adoRecordset.Fields("ADsPath").Value Set objGroup = GetObject(strPath) For Each objField In adoRecordset.Fields If (VarType(objField) = (vbArray + vbVariant)) _ Then For Each strDN In objField.Value ' Escape any forward slash characters, "/", with the backslash ' escape character. All other characters that should be escaped are. strDN = Replace(strDN, "/", "\/") ' Check dictionary object for duplicates. 'If (objGroupList.Exists(strDN) = False) Then ' Add to dictionary object. 'objGroupList.Add strDN, True ' Bind to each group member, to find member's samAccountName Set objMember = GetObject("LDAP://" & strDN) ' Output group cn, group samaAccountName and group member's samAccountName. Wscript.Echo objMember.samAccountName intCount = intCount + 1 'End if Next End If Next adoRecordset.MoveNext Loop adoRecordset.Close ' If this is the last query, exit the Do While loop. If (blnLast = True) Then Exit Do End If ' If the previous query returned no members, then the previous ' query for the next 1000 members failed. Perform one more ' query to retrieve remaining members (less than 1000). If (intCount = 0) Then blnLast = True Else ' Setup to retrieve next 1000 members. intLowRange = intHighRange + 1 intHighRange = intLowRange + intRangeStep End If Loop

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  • Reconciling a new BindingList into a master BindingList using LINQ

    - by Neo
    I have a seemingly simple problem whereby I wish to reconcile two lists so that an 'old' master list is updated by a 'new' list containing updated elements. Elements are denoted by a key property. These are my requirements: All elements in either list that have the same key results in an assignment of that element from the 'new' list over the original element in the 'old' list only if any properties have changed. Any elements in the 'new' list that have keys not in the 'old' list will be added to the 'old' list. Any elements in the 'old' list that have keys not in the 'new' list will be removed from the 'old' list. I found an equivalent problem here - http://stackoverflow.com/questions/161432/ - but it hasn't really been answered properly. So, I came up with an algorithm to iterate through the old and new lists and perform the reconciliation as per the above. Before anyone asks why I'm not just replacing the old list object with the new list object in its entirety, it's for presentation purposes - this is a BindingList bound to a grid on a GUI and I need to prevent refresh artifacts such as blinking, scrollbars moving, etc. So the list object must remain the same, only its updated elements changed. Another thing to note is that the objects in the 'new' list, even if the key is the same and all the properties are the same, are completely different instances to the equivalent objects in the 'old' list, so copying references is not an option. Below is what I've come up with so far - it's a generic extension method for a BindingList. I've put comments in to demonstrate what I'm trying to do. public static class BindingListExtension { public static void Reconcile<T>(this BindingList<T> left, BindingList<T> right, string key) { PropertyInfo piKey = typeof(T).GetProperty(key); // Go through each item in the new list in order to find all updated and new elements foreach (T newObj in right) { // First, find an object in the new list that shares its key with an object in the old list T oldObj = left.First(call => piKey.GetValue(call, null).Equals(piKey.GetValue(newObj, null))); if (oldObj != null) { // An object in each list was found with the same key, so now check to see if any properties have changed and // if any have, then assign the object from the new list over the top of the equivalent element in the old list foreach (PropertyInfo pi in typeof(T).GetProperties()) { if (!pi.GetValue(oldObj, null).Equals(pi.GetValue(newObj, null))) { left[left.IndexOf(oldObj)] = newObj; break; } } } else { // The object in the new list is brand new (has a new key), so add it to the old list left.Add(newObj); } } // Now, go through each item in the old list to find all elements with keys no longer in the new list foreach (T oldObj in left) { // Look for an element in the new list with a key matching an element in the old list if (right.First(call => piKey.GetValue(call, null).Equals(piKey.GetValue(oldObj, null))) == null) { // A matching element cannot be found in the new list, so remove the item from the old list left.Remove(oldObj); } } } } It can be called like this: _oldBindingList.Reconcile(newBindingList, "MyKey") However, I'm looking for perhaps a method of doing the same using LINQ type methods such as GroupJoin<, Join<, Select<, SelectMany<, Intersect<, etc. So far, the problem I've had is that each of these LINQ type methods result in brand new intermediary lists (as a return value) and really, I only want to modify the existing list for all the above reasons. If anyone can help with this, would be most appreciated. If not, no worries, the above method (as it were) will suffice for now. Thanks, Jason

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  • Why doesn't the default model binder update my partial view model on postback?

    - by bdnewbe
    I have a class that contains another class as one of its properties. public class SiteProperties { public SiteProperties() { DropFontFamily = "Arial, Helvetica, Sans-serif"; } public string DropFontFamily { get; set; } private ResultPageProperties m_ResultPagePropertyList; public ResultPageProperties ResultPagePropertyList { get { if (m_ResultPagePropertyList == null) m_ResultPagePropertyList = new ResultPageProperties(); return m_ResultPagePropertyList; } set { m_ResultPagePropertyList = value; } } } The second class has just one property public class ResultPageProperties { public ResultPageProperties() { ResultFontFamily = "Arial, Helvetica, Sans-serif"; } public string ResultFontFamily { get; set; } } My controller just grabs the SiteProperties and returns the view. On submit, it accepts SiteProperties and returns the same view. public class CompanyController : Controller { public ActionResult SiteOptions(int id) { SiteProperties site = new SiteProperties(); PopulateProperyDropDownLists(); return View("SiteOptions", site); } [AcceptVerbs(HttpVerbs.Post)] public ActionResult SiteOptions(SiteProperties properties) { PopulateProperyDropDownLists(); return View("SiteOptions", properties); } private void PopulateProperyDropDownLists() { var fontFamilyList = new List<SelectListItem>(); fontFamilyList.Add(new SelectListItem() { Text = "Arial, Helvetica, Sans-serif", Value = "Arial, Helvetica, Sans-serif" }); fontFamilyList.Add(new SelectListItem() { Text = "Times New Roman, Times, serif", Value = "Times New Roman, Times, serif" }); fontFamilyList.Add(new SelectListItem() { Text = "Courier New, Courier, Monospace", Value = "Courier New, Courier, Monospace" }); ViewData["FontFamilyList"] = fontFamilyList; } } The view contains a partial view that renders the ResultPageProperties Model. <% using (Html.BeginForm("SiteOptions", "Company", FormMethod.Post)) {%> <p><input type="submit" value="Submit" /></p> <div>View level input</div> <div> <label>Font family</label><br /> <%= Html.DropDownListFor(m => m.DropFontFamily, ViewData["FontFamilyList"] as List<SelectListItem>, new { Class = "UpdatesDropDownExample" })%> </div> <% Html.RenderPartial("ResultPagePropertyInput", Model.ResultPagePropertyList); %> <% } %> The partial is just <div style='margin-top: 1em;'>View level input</div> <div> <label>Font family</label><br /> <%= Html.DropDownListFor(m => m.ResultFontFamily, ViewData["FontFamilyList"] as List<SelectListItem>, new { Class = "UpdatesResultPageExample" })%> </div> OK, so when the page renders, you get "Arial, ..." in both selects. If you choose another option for both and click submit, the binder populates the SiteProperties object and passes it to the controller. However, the ResultFontFamily always contains the original value. I was expecting it to have the value the user selected. What am I missing?

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  • Using CreateSourceQuery in CTP4 Code First

    - by Adam Rackis
    I'm guessing this is impossible, but I'll throw it out there anyway. Is it possible to use CreateSourceQuery when programming with the EF4 CodeFirst API, in CTP4? I'd like to eagerly load properties attached to a collection of properties, like this: var sourceQuery = this.CurrentInvoice.PropertyInvoices.CreateSourceQuery(); sourceQuery.Include("Property").ToList(); But of course CreateSourceQuery is defined on EntityCollection<T>, whereas CodeFirst uses plain old ICollection (obviously). Is there some way to convert? I've gotten the below to work, but it's not quite what I'm looking for. Anyone know how to go from what's below to what's above (code below is from a class that inherits DbContext)? ObjectSet<Person> OSPeople = base.ObjectContext.CreateObjectSet<Person>(); OSPeople.Include(Pinner => Pinner.Books).ToList(); Thanks! EDIT: here's my version of the solution posted by zeeshanhirani - who's book by the way is amazing! dynamic result; if (invoice.PropertyInvoices is EntityCollection<PropertyInvoice>) result = (invoices.PropertyInvoices as EntityCollection<PropertyInvoice>).CreateSourceQuery().Yadda.Yadda.Yadda else //must be a unit test! result = invoices.PropertyInvoices; return result.ToList(); EDIT2: Ok, I just realized that you can't dispatch extension methods whilst using dynamic. So I guess we're not quite as dynamic as Ruby, but the example above is easily modifiable to comport with this restriction EDIT3: As mentioned in zeeshanhirani's blog post, this only works if (and only if) you have change-enabled proxies, which will get created if all of your properties are declared virtual. Here's another version of what the method might look like to use CreateSourceQuery with POCOs public class Person { public virtual int ID { get; set; } public virtual string FName { get; set; } public virtual string LName { get; set; } public virtual double Weight { get; set; } public virtual ICollection<Book> Books { get; set; } } public class Book { public virtual int ID { get; set; } public virtual string Title { get; set; } public virtual int Pages { get; set; } public virtual int OwnerID { get; set; } public virtual ICollection<Genre> Genres { get; set; } public virtual Person Owner { get; set; } } public class Genre { public virtual int ID { get; set; } public virtual string Name { get; set; } public virtual Genre ParentGenre { get; set; } public virtual ICollection<Book> Books { get; set; } } public class BookContext : DbContext { public void PrimeBooksCollectionToIncludeGenres(Person P) { if (P.Books is EntityCollection<Book>) (P.Books as EntityCollection<Book>).CreateSourceQuery().Include(b => b.Genres).ToList(); }

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  • Many to many self join through junction table

    - by Peter
    I have an EF model that can self-reference through an intermediary class to define a parent/child relationship. I know how to do a pure many-to-many relationship using the Map command, but for some reason going through this intermediary class is causing problems with my mappings. The intermediary class provides additional properties for the relationship. See the classes, modelBinder logic and error below: public class Equipment { [Key] public int EquipmentId { get; set; } public virtual List<ChildRecord> Parents { get; set; } public virtual List<ChildRecord> Children { get; set; } } public class ChildRecord { [Key] public int ChildId { get; set; } [Required] public int Quantity { get; set; } [Required] public Equipment Parent { get; set; } [Required] public Equipment Child { get; set; } } I've tried building the mappings in both directions, though I only keep one set in at a time: modelBuilder.Entity<ChildRecord>() .HasRequired(x => x.Parent) .WithMany(x => x.Children ) .WillCascadeOnDelete(false); modelBuilder.Entity<ChildRecord>() .HasRequired(x => x.Child) .WithMany(x => x.Parents) .WillCascadeOnDelete(false); OR modelBuilder.Entity<Equipment>() .HasMany(x => x.Parents) .WithRequired(x => x.Child) .WillCascadeOnDelete(false); modelBuilder.Entity<Equipment>() .HasMany(x => x.Children) .WithRequired(x => x.Parent) .WillCascadeOnDelete(false); Regardless of which set I use, I get the error: The foreign key component 'Child' is not a declared property on type 'ChildRecord'. Verify that it has not been explicitly excluded from the model and that it is a valid primitive property. when I try do deploy my ef model to the database. If I build it without the modelBinder logic in place then I get two ID columns for Child and two ID columns for Parent in my ChildRecord table. This makes sense since it tries to auto create the navigation properties from Equipment and doesn't know that there are already properties in ChildRecord to fulfill this need. I tried using Data Annotations on the class, and no modelBuilder code, this failed with the same error as above: [Required] [ForeignKey("EquipmentId")] public Equipment Parent { get; set; } [Required] [ForeignKey("EquipmentId")] public Equipment Child { get; set; } AND [InverseProperty("Child")] public virtual List<ChildRecord> Parents { get; set; } [InverseProperty("Parent")] public virtual List<ChildRecord> Children { get; set; } I've looked at various other answers around the internet/SO, and the common difference seems to be that I am self joining where as all the answers I can find are for two different types. Entity Framework Code First Many to Many Setup For Existing Tables Many to many relationship with junction table in Entity Framework? Creating many to many junction table in Entity Framework

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  • A view interface for large object/array dumps

    - by user685107
    I want to embed in a page a detailed structure report of my model objects, like print_r() or var_export() produce (now I’m doing this with running var_export() on get_object_vars()). But what I actually want to see is only some properties (in most cases), but at this moment I have to use Ctrl+F and seek the variable I want, instead of just staring at it right after the page completes loading. So I’m embedding buttons to show/hide large arrays etc. but thought: ‘What if there already is the thing I do right now?’ So is there? Update: What would your ideal interface look like? First of all, dumped models fit in the first screen. All the properties can be seen at the first look at the screen (there are not many of them, around 10 per each, three models total, so it is possible). Small arrays can be shown unrolled too. Let the size of the array to count it as ‘small’ be definable. Ideally, the user can see values of the properties without doing any click, scrolling the screen or typing something. There must be some improvements to representing the values, say, if an array is empty, show array ‘My_big_array’ is empty and if a boolean variable starting with is_, has_, had_ has a false as the value, make the variable (let us take is_available for example) shown as is_NOT_available in red, and if it has true as the value, show is_available in green. Without any value shown. The same goes for defined constants. That would be ideal. I want to make focus on this kind of switches. Krumo seems useful, but since it always closes up the variable without making difference of how large it is, I cannot use it as is, but there might appear something similar on github soon :) Second update starts here: Any programmer who sees is_available = false will know what it means, no need to do more Bringing in color indication I forgot about one thing: the ‘switches’ let’s call them so, may me important or not. So I have right now some of them that will show in green or red, this is for something global, like caching, which is shown as Caching is… ON with ‘ON’ written in green, (and ‘OFF’ in red when disabled) while the words about what it is, i.e. ‘Caching is… ’ are written in black. And some which are not so important, for example I haven’t defined REVEAL_TIES is… not set with ‘not set’ written in gray, while the words describing what it is stay in black. And if it would be set the whole phrase would be in black since there is nothing important: if this small utility for showing some undercover things is working, I will see some messages after it, if it isn’t — site will be working independently of its state. Dividing switches into important ones and not with corresponding color match should improve readability, especially for those users who are not programmers and just enabled debug mode because some guy from bugzilla said do that — for them it would help to understand what is important and what is not.

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  • September 2011 Release of the Ajax Control Toolkit

    - by Stephen Walther
    I’m happy to announce the release of the September 2011 Ajax Control Toolkit. This release has several important new features including: Date ranges – When using the Calendar extender, you can specify a start and end date and a user can pick only those dates which fall within the specified range. This was the fourth top-voted feature request for the Ajax Control Toolkit at CodePlex. Twitter Control – You can use the new Twitter control to display recent tweets associated with a particular Twitter user or tweets which match a search query. Gravatar Control – You can use the new Gravatar control to display a unique image for each user of your website. Users can upload custom images to the Gravatar.com website or the Gravatar control can display a unique, auto-generated, image for a user. You can download this release this very minute by visiting CodePlex: http://AjaxControlToolkit.CodePlex.com Alternatively, you can execute the following command from the Visual Studio NuGet console: Improvements to the Ajax Control Toolkit Calendar Control The Ajax Control Toolkit Calendar extender control is one of the most heavily used controls from the Ajax Control Toolkit. The developers on the Superexpert team spent the last sprint focusing on improving this control. There are three important changes that we made to the Calendar control: we added support for date ranges, we added support for highlighting today’s date, and we made fixes to several bugs related to time zones and daylight savings. Using Calendar Date Ranges One of the top-voted feature requests for the Ajax Control Toolkit was a request to add support for date ranges to the Calendar control (this was the fourth most voted feature request at CodePlex). With the latest release of the Ajax Control Toolkit, the Calendar extender now supports date ranges. For example, the following page illustrates how you can create a popup calendar which allows a user only to pick dates between March 2, 2009 and May 16, 2009. <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="CalendarDateRange.aspx.cs" Inherits="WebApplication1.CalendarDateRange" %> <%@ Register TagPrefix="asp" Namespace="AjaxControlToolkit" Assembly="AjaxControlToolkit" %> <html> <head runat="server"> <title>Calendar Date Range</title> </head> <body> <form id="form1" runat="server"> <asp:ToolkitScriptManager ID="tsm" runat="server" /> <asp:TextBox ID="txtHotelReservationDate" runat="server" /> <asp:CalendarExtender ID="Calendar1" TargetControlID="txtHotelReservationDate" StartDate="3/2/2009" EndDate="5/16/2009" SelectedDate="3/2/2009" runat="server" /> </form> </body> </html> This page contains three controls: an Ajax Control Toolkit ToolkitScriptManager control, a standard ASP.NET TextBox control, and an Ajax Control Toolkit CalendarExtender control. Notice that the Calendar control includes StartDate and EndDate properties which restrict the range of valid dates. The Calendar control shows days, months, and years outside of the valid range as struck out. You cannot select days, months, or years which fall outside of the range. The following video illustrates interacting with the new date range feature: If you want to experiment with a live version of the Ajax Control Toolkit Calendar extender control then you can visit the Calendar Sample Page at the Ajax Control Toolkit Sample Site. Highlighted Today’s Date Another highly requested feature for the Calendar control was support for highlighting today’s date. The Calendar control now highlights the user’s current date regardless of the user’s time zone. Fixes to Time Zone and Daylight Savings Time Bugs We fixed several significant Calendar extender bugs related to time zones and daylight savings time. For example, previously, when you set the Calendar control’s SelectedDate property to the value 1/1/2007 then the selected data would appear as 12/31/2006 or 1/1/2007 or 1/2/2007 depending on the server time zone. For example, if your server time zone was set to Samoa (UTC-11:00), then setting SelectedDate=”1/1/2007” would result in “12/31/2006” being selected in the Calendar. Users of the Calendar extender control found this behavior confusing. After careful consideration, we decided to change the Calendar extender so that it interprets all dates as UTC dates. In other words, if you set StartDate=”1/1/2007” then the Calendar extender parses the date as 1/1/2007 UTC instead of parsing the date according to the server time zone. By interpreting all dates as UTC dates, we avoid all of the reported issues with the SelectedDate property showing the wrong date. Furthermore, when you set the StartDate and EndDate properties, you know that the same StartDate and EndDate will be selected regardless of the time zone associated with the server or associated with the browser. The date 1/1/2007 will always be the date 1/1/2007. The New Twitter Control This release of the Ajax Control Toolkit introduces a new twitter control. You can use the Twitter control to display recent tweets associated with a particular twitter user. You also can use this control to show the results of a twitter search. The following page illustrates how you can use the Twitter control to display recent tweets made by Scott Hanselman: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="TwitterProfile.aspx.cs" Inherits="WebApplication1.TwitterProfile" %> <%@ Register TagPrefix="asp" Namespace="AjaxControlToolkit" Assembly="AjaxControlToolkit" %> <html > <head runat="server"> <title>Twitter Profile</title> </head> <body> <form id="form1" runat="server"> <asp:ToolkitScriptManager ID="tsm" runat="server" /> <asp:Twitter ID="Twitter1" ScreenName="shanselman" runat="server" /> </form> </body> </html> This page includes two Ajax Control Toolkit controls: the ToolkitScriptManager control and the Twitter control. The Twitter control is set to display tweets from Scott Hanselman (shanselman): You also can use the Twitter control to display the results of a search query. For example, the following page displays all recent tweets related to the Ajax Control Toolkit: Twitter limits the number of times that you can interact with their API in an hour. Twitter recommends that you cache results on the server (https://dev.twitter.com/docs/rate-limiting). By default, the Twitter control caches results on the server for a duration of 5 minutes. You can modify the cache duration by assigning a value (in seconds) to the Twitter control's CacheDuration property. The Twitter control wraps a standard ASP.NET ListView control. You can customize the appearance of the Twitter control by modifying its LayoutTemplate, StatusTemplate, AlternatingStatusTemplate, and EmptyDataTemplate. To learn more about the new Twitter control, visit the live Twitter Sample Page. The New Gravatar Control The September 2011 release of the Ajax Control Toolkit also includes a new Gravatar control. This control makes it easy to display a unique image for each user of your website. A Gravatar is associated with an email address. You can visit Gravatar.com and upload an image and associate the image with your email address. That way, every website which uses Gravatars (such as the www.ASP.NET website) will display your image next to your name. For example, I visited the Gravatar.com website and associated an image of a Koala Bear with the email address [email protected]. The following page illustrates how you can use the Gravatar control to display the Gravatar image associated with the [email protected] email address: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="GravatarDemo.aspx.cs" Inherits="WebApplication1.GravatarDemo" %> <%@ Register TagPrefix="asp" Namespace="AjaxControlToolkit" Assembly="AjaxControlToolkit" %> <html xmlns="http://www.w3.org/1999/xhtml"> <head id="Head1" runat="server"> <title>Gravatar Demo</title> </head> <body> <form id="form1" runat="server"> <asp:ToolkitScriptManager ID="tsm" runat="server" /> <asp:Gravatar ID="Gravatar1" Email="[email protected]" runat="server" /> </form> </body> </html> The page above simply displays the Gravatar image associated with the [email protected] email address: If a user has not uploaded an image to Gravatar.com then you can auto-generate a unique image for the user from the user email address. The Gravatar control supports four types of auto-generated images: Identicon -- A different geometric pattern is generated for each unrecognized email. MonsterId -- A different image of a monster is generated for each unrecognized email. Wavatar -- A different image of a face is generated for each unrecognized email. Retro -- A different 8-bit arcade-style face is generated for each unrecognized email. For example, there is no Gravatar image associated with the email address [email protected]. The following page displays an auto-generated MonsterId for this email address: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="GravatarMonster.aspx.cs" Inherits="WebApplication1.GravatarMonster" %> <%@ Register TagPrefix="asp" Namespace="AjaxControlToolkit" Assembly="AjaxControlToolkit" %> <html xmlns="http://www.w3.org/1999/xhtml"> <head id="Head1" runat="server"> <title>Gravatar Monster</title> </head> <body> <form id="form1" runat="server"> <asp:ToolkitScriptManager ID="tsm" runat="server" /> <asp:Gravatar ID="Gravatar1" Email="[email protected]" DefaultImageBehavior="MonsterId" runat="server" /> </form> </body> </html> The page above generates the following image automatically from the supplied email address: To learn more about the properties of the new Gravatar control, visit the live Gravatar Sample Page. ASP.NET Connections Talk on the Ajax Control Toolkit If you are interested in learning more about the changes that we are making to the Ajax Control Toolkit then please come to my talk on the Ajax Control Toolkit at the upcoming ASP.NET Connections conference. In the talk, I will present a summary of the changes that we have made to the Ajax Control Toolkit over the last several months and discuss our future plans. Do you have ideas for new Ajax Control Toolkit controls? Ideas for improving the toolkit? Come to my talk – I would love to hear from you. You can register for the ASP.NET Connections conference by visiting the following website: Register for ASP.NET Connections   Summary The previous release of the Ajax Control Toolkit – the July 2011 Release – has had over 100,000 downloads. That is a huge number of developers who are working with the Ajax Control Toolkit. We are really excited about the new features which we added to the Ajax Control Toolkit in the latest September sprint. We hope that you find the updated Calender control, the new Twitter control, and the new Gravatar control valuable when building your ASP.NET Web Forms applications.

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  • Flot not displaying x axis labels correctly

    - by JVXR
    I have to display a graph with date on the X axis and Amt on the Y axis. There will be 8 lines (series) each with n months data. When I plot the graph I am sending in 6 months data for sure.( one line's data is shown below) [1251701950000, 34.50553] [1254294030000, 27.014463] [1256972350000, 26.7805] [1259567970000, 33.08871] [1262246430000, 51.987762] [1264924750000, 56.868233] However the graph shows up like this http://twitpic.com/1gbb7m The first months label is missing and last month is not aligned correctly, my flot js code is as follows $.plot($("#lgdGraphTab"),graphData, { xaxis: { mode: "time", timeformat: "%b-%y", monthNames: ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"], minTickSize: [1, "month"] }, yaxis : { tickSize: 5 }, series: { lines: { show: true , shadowSize:0}, points: { show: true } }, legend:{ container: $('#legendArea'), noColumns:8 }, clickable: true, hoverable: true });

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  • Enum in WCF RIA Services Object

    - by Blake Blackwell
    Is it possible to have an enum with WCF RIA Services? When I check the generated code for my custom POCO class I don't see the enum property generated. Here is an example of what I'm trying to do: public class Legend { public enum ViewStateType { OnExpanded = 1, OnContracted = 2, OffExpanded = 3, OffContracted = 4 } [Key] public Guid LegendId { get; set; } [EnumDataType(typeof(ViewStateType))] public ViewStateType ViewState { get; set; } } I tried with and without the EnumDataType attribute.

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  • jqGrid - Problems opening in jquery tabs (on Firefox and Google Chrome)

    - by Ben Hargreaves
    I have developed a very simple MVC app to test out trirand's jqGrid for MVC. The app opens a jqgrid in a jquery tab group and everything is ok with IE. However when I use Firefox jqgrid only opens occasionaly in the first tab (but not under any other tab), and in Chrome my jqgrids dont appear to open under any tab of the group. I'm a bit of an MVC newbie (and have only been testing jqgrid out for a few days), but I know my users will want to use different browsers. Trirand have not come back with any answer so wondered if anyone else had had a similar issue. I have really just implemented jqgrid as per the controllers and model in the sample application on the Trirand site, and then combined it with a straightforward jquery tab group. My MVC Details Page is as follows; <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<PRAMSAPP.Models.Family>" %> <%@ Import Namespace="Trirand.Web.Mvc" %> <%@ Import Namespace="PRAMSAPP.Controllers" %> <%@ Import Namespace="PRAMSAPP.Models" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Details </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="/scripts/jquery-ui-1.7.2.custom.css" /> <script type="text/javascript" src="/scripts/jquery-1.3.2.min.js"></script> <script type="text/javascript" src="/scripts/jquery-ui-1.7.2.custom.min.js"></script> <fieldset> <legend>Family</legend> <div class="display-field"><%= Html.Encode(Model.FamilyID) %></div> <div class="display-field"><%= Html.Encode(Model.FamilySurname) %></div> </fieldset> <div id="tabs"> <ul> <li> <%= Html.ActionLink("GridChildren", "GridDemo", new { controller = "Grid", id = Model.FamilyID })%> </li> <li> <%= Html.ActionLink("Children", "ShowFamiliesChildren", new { famid = Model.FamilyID, page = Page})%> </li> </ul> </div> <p> <%= Html.ActionLink("Edit", "Edit", new { id=Model.FamilyID }) %> | <%= Html.ActionLink("Back to List", "Index") %> </p> <script type="text/javascript"> $(function() { $('#tabs').tabs(); }); </script> </asp:Content> And My Controller page is as follows; <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<PRAMSAPP.Models.FamiliesChildrenJqGridModel>" %> <%@ Import Namespace="Trirand.Web.Mvc" %> <%@ Import Namespace="PRAMSAPP.Controllers" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <!-- The jQuery UI theme that will be used by the grid --> <link rel="stylesheet" type="text/css" media="screen" href="/Content/themes/redmond/jquery-ui-1.7.1.custom.css" /> <!-- The Css UI theme extension of jqGrid --> <link rel="stylesheet" type="text/css" media="screen" href="/Content/themes/ui.jqgrid.css" /> <!-- jQuery library is a prerequisite for jqGrid --> <script type="text/javascript" src="/Scripts/jquery-1.3.2.min.js"></script> <!-- language pack - MUST be included before the jqGrid javascript --> <script type="text/javascript" src="/Scripts/grid.locale-en.js"></script> <script type="text/javascript" src="/Scripts/jqgrid/jquery.jqGrid.min.js"></script> </head> <body> <div> <%= Html.Trirand().JQGrid(Model.FamiliesChildrenGrid, "JQGrid1") %> </div> </body>

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  • Passing multiple simple POST Values to ASP.NET Web API

    - by Rick Strahl
    A few weeks backs I posted a blog post  about what does and doesn't work with ASP.NET Web API when it comes to POSTing data to a Web API controller. One of the features that doesn't work out of the box - somewhat unexpectedly -  is the ability to map POST form variables to simple parameters of a Web API method. For example imagine you have this form and you want to post this data to a Web API end point like this via AJAX: <form> Name: <input type="name" name="name" value="Rick" /> Value: <input type="value" name="value" value="12" /> Entered: <input type="entered" name="entered" value="12/01/2011" /> <input type="button" id="btnSend" value="Send" /> </form> <script type="text/javascript"> $("#btnSend").click( function() { $.post("samples/PostMultipleSimpleValues?action=kazam", $("form").serialize(), function (result) { alert(result); }); }); </script> or you might do this more explicitly by creating a simple client map and specifying the POST values directly by hand:$.post("samples/PostMultipleSimpleValues?action=kazam", { name: "Rick", value: 1, entered: "12/01/2012" }, $("form").serialize(), function (result) { alert(result); }); On the wire this generates a simple POST request with Url Encoded values in the content:POST /AspNetWebApi/samples/PostMultipleSimpleValues?action=kazam HTTP/1.1 Host: localhost User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:15.0) Gecko/20100101 Firefox/15.0.1 Accept: application/json Connection: keep-alive Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With: XMLHttpRequest Referer: http://localhost/AspNetWebApi/FormPostTest.html Content-Length: 41 Pragma: no-cache Cache-Control: no-cachename=Rick&value=12&entered=12%2F10%2F2011 Seems simple enough, right? We are basically posting 3 form variables and 1 query string value to the server. Unfortunately Web API can't handle request out of the box. If I create a method like this:[HttpPost] public string PostMultipleSimpleValues(string name, int value, DateTime entered, string action = null) { return string.Format("Name: {0}, Value: {1}, Date: {2}, Action: {3}", name, value, entered, action); }You'll find that you get an HTTP 404 error and { "Message": "No HTTP resource was found that matches the request URI…"} Yes, it's possible to pass multiple POST parameters of course, but Web API expects you to use Model Binding for this - mapping the post parameters to a strongly typed .NET object, not to single parameters. Alternately you can also accept a FormDataCollection parameter on your API method to get a name value collection of all POSTed values. If you're using JSON only, using the dynamic JObject/JValue objects might also work. ModelBinding is fine in many use cases, but can quickly become overkill if you only need to pass a couple of simple parameters to many methods. Especially in applications with many, many AJAX callbacks the 'parameter mapping type' per method signature can lead to serious class pollution in a project very quickly. Simple POST variables are also commonly used in AJAX applications to pass data to the server, even in many complex public APIs. So this is not an uncommon use case, and - maybe more so a behavior that I would have expected Web API to support natively. The question "Why aren't my POST parameters mapping to Web API method parameters" is already a frequent one… So this is something that I think is fairly important, but unfortunately missing in the base Web API installation. Creating a Custom Parameter Binder Luckily Web API is greatly extensible and there's a way to create a custom Parameter Binding to provide this functionality! Although this solution took me a long while to find and then only with the help of some folks Microsoft (thanks Hong Mei!!!), it's not difficult to hook up in your own projects. It requires one small class and a GlobalConfiguration hookup. Web API parameter bindings allow you to intercept processing of individual parameters - they deal with mapping parameters to the signature as well as converting the parameters to the actual values that are returned. Here's the implementation of the SimplePostVariableParameterBinding class:public class SimplePostVariableParameterBinding : HttpParameterBinding { private const string MultipleBodyParameters = "MultipleBodyParameters"; public SimplePostVariableParameterBinding(HttpParameterDescriptor descriptor) : base(descriptor) { } /// <summary> /// Check for simple binding parameters in POST data. Bind POST /// data as well as query string data /// </summary> public override Task ExecuteBindingAsync(ModelMetadataProvider metadataProvider, HttpActionContext actionContext, CancellationToken cancellationToken) { // Body can only be read once, so read and cache it NameValueCollection col = TryReadBody(actionContext.Request); string stringValue = null; if (col != null) stringValue = col[Descriptor.ParameterName]; // try reading query string if we have no POST/PUT match if (stringValue == null) { var query = actionContext.Request.GetQueryNameValuePairs(); if (query != null) { var matches = query.Where(kv => kv.Key.ToLower() == Descriptor.ParameterName.ToLower()); if (matches.Count() > 0) stringValue = matches.First().Value; } } object value = StringToType(stringValue); // Set the binding result here SetValue(actionContext, value); // now, we can return a completed task with no result TaskCompletionSource<AsyncVoid> tcs = new TaskCompletionSource<AsyncVoid>(); tcs.SetResult(default(AsyncVoid)); return tcs.Task; } private object StringToType(string stringValue) { object value = null; if (stringValue == null) value = null; else if (Descriptor.ParameterType == typeof(string)) value = stringValue; else if (Descriptor.ParameterType == typeof(int)) value = int.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(Int32)) value = Int32.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(Int64)) value = Int64.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(decimal)) value = decimal.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(double)) value = double.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(DateTime)) value = DateTime.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(bool)) { value = false; if (stringValue == "true" || stringValue == "on" || stringValue == "1") value = true; } else value = stringValue; return value; } /// <summary> /// Read and cache the request body /// </summary> /// <param name="request"></param> /// <returns></returns> private NameValueCollection TryReadBody(HttpRequestMessage request) { object result = null; // try to read out of cache first if (!request.Properties.TryGetValue(MultipleBodyParameters, out result)) { // parsing the string like firstname=Hongmei&lastname=Ge result = request.Content.ReadAsFormDataAsync().Result; request.Properties.Add(MultipleBodyParameters, result); } return result as NameValueCollection; } private struct AsyncVoid { } }   The ExecuteBindingAsync method is fired for each parameter that is mapped and sent for conversion. This custom binding is fired only if the incoming parameter is a simple type (that gets defined later when I hook up the binding), so this binding never fires on complex types or if the first type is not a simple type. For the first parameter of a request the Binding first reads the request body into a NameValueCollection and caches that in the request.Properties collection. The request body can only be read once, so the first parameter request reads it and then caches it. Subsequent parameters then use the cached POST value collection. Once the form collection is available the value of the parameter is read, and the value is translated into the target type requested by the Descriptor. SetValue writes out the value to be mapped. Once you have the ParameterBinding in place, the binding has to be assigned. This is done along with all other Web API configuration tasks at application startup in global.asax's Application_Start:GlobalConfiguration.Configuration.ParameterBindingRules .Insert(0, (HttpParameterDescriptor descriptor) => { var supportedMethods = descriptor.ActionDescriptor.SupportedHttpMethods; // Only apply this binder on POST and PUT operations if (supportedMethods.Contains(HttpMethod.Post) || supportedMethods.Contains(HttpMethod.Put)) { var supportedTypes = new Type[] { typeof(string), typeof(int), typeof(decimal), typeof(double), typeof(bool), typeof(DateTime) }; if (supportedTypes.Where(typ => typ == descriptor.ParameterType).Count() > 0) return new SimplePostVariableParameterBinding(descriptor); } // let the default bindings do their work return null; });   The ParameterBindingRules.Insert method takes a delegate that checks which type of requests it should handle. The logic here checks whether the request is POST or PUT and whether the parameter type is a simple type that is supported. Web API calls this delegate once for each method signature it tries to map and the delegate returns null to indicate it's not handling this parameter, or it returns a new parameter binding instance - in this case the SimplePostVariableParameterBinding. Once the parameter binding and this hook up code is in place, you can now pass simple POST values to methods with simple parameters. The examples I showed above should now work in addition to the standard bindings. Summary Clearly this is not easy to discover. I spent quite a bit of time digging through the Web API source trying to figure this out on my own without much luck. It took Hong Mei at Micrsoft to provide a base example as I asked around so I can't take credit for this solution :-). But once you know where to look, Web API is brilliantly extensible to make it relatively easy to customize the parameter behavior. I'm very stoked that this got resolved  - in the last two months I've had two customers with projects that decided not to use Web API in AJAX heavy SPA applications because this POST variable mapping wasn't available. This might actually change their mind to still switch back and take advantage of the many great features in Web API. I too frequently use plain POST variables for communicating with server AJAX handlers and while I could have worked around this (with untyped JObject or the Form collection mostly), having proper POST to parameter mapping makes things much easier. I said this in my last post on POST data and say it again here: I think POST to method parameter mapping should have been shipped in the box with Web API, because without knowing about this limitation the expectation is that simple POST variables map to parameters just like query string values do. I hope Microsoft considers including this type of functionality natively in the next version of Web API natively or at least as a built-in HttpParameterBinding that can be just added. This is especially true, since this binding doesn't affect existing bindings. Resources SimplePostVariableParameterBinding Source on GitHub Global.asax hookup source Mapping URL Encoded Post Values in  ASP.NET Web API© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api  AJAX   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • ASP.NET Web Forms Extensibility: Providers

    - by Ricardo Peres
    Introduction This will be the first of a number of posts on ASP.NET extensibility. At this moment I don’t know exactly how many will be and I only know a couple of subjects that I want to talk about, so more will come in the next days. I have the sensation that the providers offered by ASP.NET are not widely know, although everyone uses, for example, sessions, they may not be aware of the extensibility points that Microsoft included. This post won’t go into details of how to configure and extend each of the providers, but will hopefully give some pointers on that direction. Canonical These are the most widely known and used providers, coming from ASP.NET 1, chances are, you have used them already. Good support for invoking client side, either from a .NET application or from JavaScript. Lots of server-side controls use them, such as the Login control for example. Membership The Membership provider is responsible for managing registered users, including creating new ones, authenticating them, changing passwords, etc. ASP.NET comes with two implementations, one that uses a SQL Server database and another that uses the Active Directory. The base class is Membership and new providers are registered on the membership section on the Web.config file, as well as parameters for specifying minimum password lengths, complexities, maximum age, etc. One reason for creating a custom provider would be, for example, storing membership information in a different database engine. 1: <membership defaultProvider="MyProvider"> 2: <providers> 3: <add name="MyProvider" type="MyClass, MyAssembly"/> 4: </providers> 5: </membership> Role The Role provider assigns roles to authenticated users. The base class is Role and there are three out of the box implementations: XML-based, SQL Server and Windows-based. Also registered on Web.config through the roleManager section, where you can also say if your roles should be cached on a cookie. If you want your roles to come from a different place, implement a custom provider. 1: <roleManager defaultProvider="MyProvider"> 2: <providers> 3: <add name="MyProvider" type="MyClass, MyAssembly" /> 4: </providers> 5: </roleManager> Profile The Profile provider allows defining a set of properties that will be tied and made available to authenticated or even anonymous ones, which must be tracked by using anonymous authentication. The base class is Profile and the only included implementation stores these settings in a SQL Server database. Configured through profile section, where you also specify the properties to make available, a custom provider would allow storing these properties in different locations. 1: <profile defaultProvider="MyProvider"> 2: <providers> 3: <add name="MyProvider" type="MyClass, MyAssembly"/> 4: </providers> 5: </profile> Basic OK, I didn’t know what to call these, so Basic is probably as good as a name as anything else. Not supported client-side (doesn’t even make sense). Session The Session provider allows storing data tied to the current “session”, which is normally created when a user first accesses the site, even when it is not yet authenticated, and remains all the way. The base class and only included implementation is SessionStateStoreProviderBase and it is capable of storing data in one of three locations: In the process memory (default, not suitable for web farms or increased reliability); A SQL Server database (best for reliability and clustering); The ASP.NET State Service, which is a Windows Service that is installed with the .NET Framework (ok for clustering). The configuration is made through the sessionState section. By adding a custom Session provider, you can store the data in different locations – think for example of a distributed cache. 1: <sessionState customProvider=”MyProvider”> 2: <providers> 3: <add name=”MyProvider” type=”MyClass, MyAssembly” /> 4: </providers> 5: </sessionState> Resource A not so known provider, allows you to change the origin of localized resource elements. By default, these come from RESX files and are used whenever you use the Resources expression builder or the GetGlobalResourceObject and GetLocalResourceObject methods, but if you implement a custom provider, you can have these elements come from some place else, such as a database. The base class is ResourceProviderFactory and there’s only one internal implementation which uses these RESX files. Configuration is through the globalization section. 1: <globalization resourceProviderFactoryType="MyClass, MyAssembly" /> Health Monitoring Health Monitoring is also probably not so well known, and actually not a good name for it. First, in order to understand what it does, you have to know that ASP.NET fires “events” at specific times and when specific things happen, such as when logging in, an exception is raised. These are not user interface events and you can create your own and fire them, nothing will happen, but the Health Monitoring provider will detect it. You can configure it to do things when certain conditions are met, such as a number of events being fired in a certain amount of time. You define these rules and route them to a specific provider, which must inherit from WebEventProvider. Out of the box implementations include sending mails, logging to a SQL Server database, writing to the Windows Event Log, Windows Management Instrumentation, the IIS 7 Trace infrastructure or the debugger Trace. Its configuration is achieved by the healthMonitoring section and a reason for implementing a custom provider would be, for example, locking down a web application in the event of a significant number of failed login attempts occurring in a small period of time. 1: <healthMonitoring> 2: <providers> 3: <add name="MyProvider" type="MyClass, MyAssembly"/> 4: </providers> 5: </healthMonitoring> Sitemap The Sitemap provider allows defining the site’s navigation structure and associated required permissions for each node, in a tree-like fashion. Usually this is statically defined, and the included provider allows it, by supplying this structure in a Web.sitemap XML file. The base class is SiteMapProvider and you can extend it in order to supply you own source for the site’s structure, which may even be dynamic. Its configuration must be done through the siteMap section. 1: <siteMap defaultProvider="MyProvider"> 2: <providers><add name="MyProvider" type="MyClass, MyAssembly" /> 3: </providers> 4: </siteMap> Web Part Personalization Web Parts are better known by SharePoint users, but since ASP.NET 2.0 they are included in the core Framework. Web Parts are server-side controls that offer certain possibilities of configuration by clients visiting the page where they are located. The infrastructure handles this configuration per user or globally for all users and this provider is responsible for just that. The base class is PersonalizationProvider and the only included implementation stores settings on SQL Server. Add new providers through the personalization section. 1: <webParts> 2: <personalization defaultProvider="MyProvider"> 3: <providers> 4: <add name="MyProvider" type="MyClass, MyAssembly"/> 5: </providers> 6: </personalization> 7: </webParts> Build The Build provider is responsible for compiling whatever files are present on your web folder. There’s a base class, BuildProvider, and, as can be expected, internal implementations for building pages (ASPX), master pages (Master), user web controls (ASCX), handlers (ASHX), themes (Skin), XML Schemas (XSD), web services (ASMX, SVC), resources (RESX), browser capabilities files (Browser) and so on. You would write a build provider if you wanted to generate code from any kind of non-code file so that you have strong typing at development time. Configuration goes on the buildProviders section and it is per extension. 1: <buildProviders> 2: <add extension=".ext" type="MyClass, MyAssembly” /> 3: </buildProviders> New in ASP.NET 4 Not exactly new since they exist since 2010, but in ASP.NET terms, still new. Output Cache The Output Cache for ASPX pages and ASCX user controls is now extensible, through the Output Cache provider, which means you can implement a custom mechanism for storing and retrieving cached data, for example, in a distributed fashion. The base class is OutputCacheProvider and the only implementation is private. Configuration goes on the outputCache section and on each page and web user control you can choose the provider you want to use. 1: <caching> 2: <outputCache defaultProvider="MyProvider"> 3: <providers> 4: <add name="MyProvider" type="MyClass, MyAssembly"/> 5: </providers> 6: </outputCache> 7: </caching> Request Validation A big change introduced in ASP.NET 4 (and refined in 4.5, by the way) is the introduction of extensible request validation, by means of a Request Validation provider. This means we are not limited to either enabling or disabling event validation for all pages or for a specific page, but we now have fine control over each of the elements of the request, including cookies, headers, query string and form values. The base provider class is RequestValidator and the configuration goes on the httpRuntime section. 1: <httpRuntime requestValidationType="MyClass, MyAssembly" /> Browser Capabilities The Browser Capabilities provider is new in ASP.NET 4, although the concept exists from ASP.NET 2. The idea is to map a browser brand and version to its supported capabilities, such as JavaScript version, Flash support, ActiveX support, and so on. Previously, this was all hardcoded in .Browser files located in %WINDIR%\Microsoft.NET\Framework(64)\vXXXXX\Config\Browsers, but now you can have a class inherit from HttpCapabilitiesProvider and implement your own mechanism. Register in on the browserCaps section. 1: <browserCaps provider="MyClass, MyAssembly" /> Encoder The Encoder provider is responsible for encoding every string that is sent to the browser on a page or header. This includes for example converting special characters for their standard codes and is implemented by the base class HttpEncoder. Another implementation takes care of Anti Cross Site Scripting (XSS) attacks. Build your own by inheriting from one of these classes if you want to add some additional processing to these strings. The configuration will go on the httpRuntime section. 1: <httpRuntime encoderType="MyClass, MyAssembly" /> Conclusion That’s about it for ASP.NET providers. It was by no means a thorough description, but I hope I managed to raise your interest on this subject. There are lots of pointers on the Internet, so I only included direct references to the Framework classes and configuration sections. Stay tuned for more extensibility!

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  • Building a Windows Phone 7 Twitter Application using Silverlight

    - by ScottGu
    On Monday I had the opportunity to present the MIX 2010 Day 1 Keynote in Las Vegas (you can watch a video of it here).  In the keynote I announced the release of the Silverlight 4 Release Candidate (we’ll ship the final release of it next month) and the VS 2010 RC tools for Silverlight 4.  I also had the chance to talk for the first time about how Silverlight and XNA can now be used to build Windows Phone 7 applications. During my talk I did two quick Windows Phone 7 coding demos using Silverlight – a quick “Hello World” application and a “Twitter” data-snacking application.  Both applications were easy to build and only took a few minutes to create on stage.  Below are the steps you can follow yourself to build them on your own machines as well. [Note: In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] Building a “Hello World” Windows Phone 7 Application First make sure you’ve installed the Windows Phone Developer Tools CTP – this includes the Visual Studio 2010 Express for Windows Phone development tool (which will be free forever and is the only thing you need to develop and build Windows Phone 7 applications) as well as an add-on to the VS 2010 RC that enables phone development within the full VS 2010 as well. After you’ve downloaded and installed the Windows Phone Developer Tools CTP, launch the Visual Studio 2010 Express for Windows Phone that it installs or launch the VS 2010 RC (if you have it already installed), and then choose “File”->”New Project.”  Here, you’ll find the usual list of project template types along with a new category: “Silverlight for Windows Phone”. The first CTP offers two application project templates. The first is the “Windows Phone Application” template - this is what we’ll use for this example. The second is the “Windows Phone List Application” template - which provides the basic layout for a master-details phone application: After creating a new project, you’ll get a view of the design surface and markup. Notice that the design surface shows the phone UI, letting you easily see how your application will look while you develop. For those familiar with Visual Studio, you’ll also find the familiar ToolBox, Solution Explorer and Properties pane. For our HelloWorld application, we’ll start out by adding a TextBox and a Button from the Toolbox. Notice that you get the same design experience as you do for Silverlight on the web or desktop. You can easily resize, position and align your controls on the design surface. Changing properties is easy with the Properties pane. We’ll change the name of the TextBox that we added to username and change the page title text to “Hello world.” We’ll then write some code by double-clicking on the button and create an event handler in the code-behind file (MainPage.xaml.cs). We’ll start out by changing the title text of the application. The project template included this title as a TextBlock with the name textBlockListTitle (note that the current name incorrectly includes the word “list”; that will be fixed for the final release.)  As we write code against it we get intellisense showing the members available.  Below we’ll set the Text property of the title TextBlock to “Hello “ + the Text property of the TextBox username: We now have all the code necessary for a Hello World application.  We have two choices when it comes to deploying and running the application. We can either deploy to an actual device itself or use the built-in phone emulator: Because the phone emulator is actually the phone operating system running in a virtual machine, we’ll get the same experience developing in the emulator as on the device. For this sample, we’ll just press F5 to start the application with debugging using the emulator.  Once the phone operating system loads, the emulator will run the new “Hello world” application exactly as it would on the device: Notice that we can change several settings of the emulator experience with the emulator toolbar – which is a floating toolbar on the top right.  This includes the ability to re-size/zoom the emulator and two rotate buttons.  Zoom lets us zoom into even the smallest detail of the application: The orientation buttons allow us easily see what the application looks like in landscape mode (orientation change support is just built into the default template): Note that the emulator can be reused across F5 debug sessions - that means that we don’t have to start the emulator for every deployment. We’ve added a dialog that will help you from accidentally shutting down the emulator if you want to reuse it.  Launching an application on an already running emulator should only take ~3 seconds to deploy and run. Within our Hello World application we’ll click the “username” textbox to give it focus.  This will cause the software input panel (SIP) to open up automatically.  We can either type a message or – since we are using the emulator – just type in text.  Note that the emulator works with Windows 7 multi-touch so, if you have a touchscreen, you can see how interaction will feel on a device just by pressing the screen. We’ll enter “MIX 10” in the textbox and then click the button – this will cause the title to update to be “Hello MIX 10”: We provide the same Visual Studio experience when developing for the phone as other .NET applications. This means that we can set a breakpoint within the button event handler, press the button again and have it break within the debugger: Building a “Twitter” Windows Phone 7 Application using Silverlight Rather than just stop with “Hello World” let’s keep going and evolve it to be a basic Twitter client application. We’ll return to the design surface and add a ListBox, using the snaplines within the designer to fit it to the device screen and make the best use of phone screen real estate.  We’ll also rename the Button “Lookup”: We’ll then return to the Button event handler in Main.xaml.cs, and remove the original “Hello World” line of code and take advantage of the WebClient networking class to asynchronously download a Twitter feed. This takes three lines of code in total: (1) declaring and creating the WebClient, (2) attaching an event handler and then (3) calling the asynchronous DownloadStringAsync method. In the DownloadStringAsync call, we’ll pass a Twitter Uri plus a query string which pulls the text from the “username” TextBox. This feed will pull down the respective user’s most frequent posts in an XML format. When the call completes, the DownloadStringCompleted event is fired and our generated event handler twitter_DownloadStringCompleted will be called: The result returned from the Twitter call will come back in an XML based format.  To parse this we’ll use LINQ to XML. LINQ to XML lets us create simple queries for accessing data in an xml feed. To use this library, we’ll first need to add a reference to the assembly (right click on the References folder in the solution explorer and choose “Add Reference): We’ll then add a “using System.Xml.Linq” namespace reference at the top of the code-behind file at the top of Main.xaml.cs file: We’ll then add a simple helper class called TwitterItem to our project. TwitterItem has three string members – UserName, Message and ImageSource: We’ll then implement the twitter_DownloadStringCompleted event handler and use LINQ to XML to parse the returned XML string from Twitter.  What the query is doing is pulling out the three key pieces of information for each Twitter post from the username we passed as the query string. These are the ImageSource for their profile image, the Message of their tweet and their UserName. For each Tweet in the XML, we are creating a new TwitterItem in the IEnumerable<XElement> returned by the Linq query.  We then assign the generated TwitterItem sequence to the ListBox’s ItemsSource property: We’ll then do one more step to complete the application. In the Main.xaml file, we’ll add an ItemTemplate to the ListBox. For the demo, I used a simple template that uses databinding to show the user’s profile image, their tweet and their username. <ListBox Height="521" HorizonalAlignment="Left" Margin="0,131,0,0" Name="listBox1" VerticalAlignment="Top" Width="476"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal" Height="132"> <Image Source="{Binding ImageSource}" Height="73" Width="73" VerticalAlignment="Top" Margin="0,10,8,0"/> <StackPanel Width="370"> <TextBlock Text="{Binding UserName}" Foreground="#FFC8AB14" FontSize="28" /> <TextBlock Text="{Binding Message}" TextWrapping="Wrap" FontSize="24" /> </StackPanel> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> Now, pressing F5 again, we are able to reuse the emulator and re-run the application. Once the application has launched, we can type in a Twitter username and press the  Button to see the results. Try my Twitter user name (scottgu) and you’ll get back a result of TwitterItems in the Listbox: Try using the mouse (or if you have a touchscreen device your finger) to scroll the items in the Listbox – you should find that they move very fast within the emulator.  This is because the emulator is hardware accelerated – and so gives you the same fast performance that you get on the actual phone hardware. Summary Silverlight and the VS 2010 Tools for Windows Phone (and the corresponding Expression Blend Tools for Windows Phone) make building Windows Phone applications both really easy and fun.  At MIX this week a number of great partners (including Netflix, FourSquare, Seesmic, Shazaam, Major League Soccer, Graphic.ly, Associated Press, Jackson Fish and more) showed off some killer application prototypes they’ve built over the last few weeks.  You can watch my full day 1 keynote to see them in action. I think they start to show some of the promise and potential of using Silverlight with Windows Phone 7.  I’ll be doing more blog posts in the weeks and months ahead that cover that more. Hope this helps, Scott

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  • SQL SERVER – Concurrency Basics – Guest Post by Vinod Kumar

    - by pinaldave
    This guest post is by Vinod Kumar. Vinod Kumar has worked with SQL Server extensively since joining the industry over a decade ago. Working on various versions from SQL Server 7.0, Oracle 7.3 and other database technologies – he now works with the Microsoft Technology Center (MTC) as a Technology Architect. Let us read the blog post in Vinod’s own voice. Learning is always fun when it comes to SQL Server and learning the basics again can be more fun. I did write about Transaction Logs and recovery over my blogs and the concept of simplifying the basics is a challenge. In the real world we always see checks and queues for a process – say railway reservation, banks, customer supports etc there is a process of line and queue to facilitate everyone. Shorter the queue higher is the efficiency of system (a.k.a higher is the concurrency). Every database does implement this using checks like locking, blocking mechanisms and they implement the standards in a way to facilitate higher concurrency. In this post, let us talk about the topic of Concurrency and what are the various aspects that one needs to know about concurrency inside SQL Server. Let us learn the concepts as one-liners: Concurrency can be defined as the ability of multiple processes to access or change shared data at the same time. The greater the number of concurrent user processes that can be active without interfering with each other, the greater the concurrency of the database system. Concurrency is reduced when a process that is changing data prevents other processes from reading that data or when a process that is reading data prevents other processes from changing that data. Concurrency is also affected when multiple processes are attempting to change the same data simultaneously. Two approaches to managing concurrent data access: Optimistic Concurrency Model Pessimistic Concurrency Model Concurrency Models Pessimistic Concurrency Default behavior: acquire locks to block access to data that another process is using. Assumes that enough data modification operations are in the system that any given read operation is likely affected by a data modification made by another user (assumes conflicts will occur). Avoids conflicts by acquiring a lock on data being read so no other processes can modify that data. Also acquires locks on data being modified so no other processes can access the data for either reading or modifying. Readers block writer, writers block readers and writers. Optimistic Concurrency Assumes that there are sufficiently few conflicting data modification operations in the system that any single transaction is unlikely to modify data that another transaction is modifying. Default behavior of optimistic concurrency is to use row versioning to allow data readers to see the state of the data before the modification occurs. Older versions of the data are saved so a process reading data can see the data as it was when the process started reading and not affected by any changes being made to that data. Processes modifying the data is unaffected by processes reading the data because the reader is accessing a saved version of the data rows. Readers do not block writers and writers do not block readers, but, writers can and will block writers. Transaction Processing A transaction is the basic unit of work in SQL Server. Transaction consists of SQL commands that read and update the database but the update is not considered final until a COMMIT command is issued (at least for an explicit transaction: marked with a BEGIN TRAN and the end is marked by a COMMIT TRAN or ROLLBACK TRAN). Transactions must exhibit all the ACID properties of a transaction. ACID Properties Transaction processing must guarantee the consistency and recoverability of SQL Server databases. Ensures all transactions are performed as a single unit of work regardless of hardware or system failure. A – Atomicity C – Consistency I – Isolation D- Durability Atomicity: Each transaction is treated as all or nothing – it either commits or aborts. Consistency: ensures that a transaction won’t allow the system to arrive at an incorrect logical state – the data must always be logically correct.  Consistency is honored even in the event of a system failure. Isolation: separates concurrent transactions from the updates of other incomplete transactions. SQL Server accomplishes isolation among transactions by locking data or creating row versions. Durability: After a transaction commits, the durability property ensures that the effects of the transaction persist even if a system failure occurs. If a system failure occurs while a transaction is in progress, the transaction is completely undone, leaving no partial effects on data. Transaction Dependencies In addition to supporting all four ACID properties, a transaction might exhibit few other behaviors (known as dependency problems or consistency problems). Lost Updates: Occur when two processes read the same data and both manipulate the data, changing its value and then both try to update the original data to the new value. The second process might overwrite the first update completely. Dirty Reads: Occurs when a process reads uncommitted data. If one process has changed data but not yet committed the change, another process reading the data will read it in an inconsistent state. Non-repeatable Reads: A read is non-repeatable if a process might get different values when reading the same data in two reads within the same transaction. This can happen when another process changes the data in between the reads that the first process is doing. Phantoms: Occurs when membership in a set changes. It occurs if two SELECT operations using the same predicate in the same transaction return a different number of rows. Isolation Levels SQL Server supports 5 isolation levels that control the behavior of read operations. Read Uncommitted All behaviors except for lost updates are possible. Implemented by allowing the read operations to not take any locks, and because of this, it won’t be blocked by conflicting locks acquired by other processes. The process can read data that another process has modified but not yet committed. When using the read uncommitted isolation level and scanning an entire table, SQL Server can decide to do an allocation order scan (in page-number order) instead of a logical order scan (following page pointers). If another process doing concurrent operations changes data and move rows to a new location in the table, the allocation order scan can end up reading the same row twice. Also can happen if you have read a row before it is updated and then an update moves the row to a higher page number than your scan encounters later. Performing an allocation order scan under Read Uncommitted can cause you to miss a row completely – can happen when a row on a high page number that hasn’t been read yet is updated and moved to a lower page number that has already been read. Read Committed Two varieties of read committed isolation: optimistic and pessimistic (default). Ensures that a read never reads data that another application hasn’t committed. If another transaction is updating data and has exclusive locks on data, your transaction will have to wait for the locks to be released. Your transaction must put share locks on data that are visited, which means that data might be unavailable for others to use. A share lock doesn’t prevent others from reading but prevents them from updating. Read committed (snapshot) ensures that an operation never reads uncommitted data, but not by forcing other processes to wait. SQL Server generates a version of the changed row with its previous committed values. Data being changed is still locked but other processes can see the previous versions of the data as it was before the update operation began. Repeatable Read This is a Pessimistic isolation level. Ensures that if a transaction revisits data or a query is reissued the data doesn’t change. That is, issuing the same query twice within a transaction cannot pickup any changes to data values made by another user’s transaction because no changes can be made by other transactions. However, this does allow phantom rows to appear. Preventing non-repeatable read is a desirable safeguard but cost is that all shared locks in a transaction must be held until the completion of the transaction. Snapshot Snapshot Isolation (SI) is an optimistic isolation level. Allows for processes to read older versions of committed data if the current version is locked. Difference between snapshot and read committed has to do with how old the older versions have to be. It’s possible to have two transactions executing simultaneously that give us a result that is not possible in any serial execution. Serializable This is the strongest of the pessimistic isolation level. Adds to repeatable read isolation level by ensuring that if a query is reissued rows were not added in the interim, i.e, phantoms do not appear. Preventing phantoms is another desirable safeguard, but cost of this extra safeguard is similar to that of repeatable read – all shared locks in a transaction must be held until the transaction completes. In addition serializable isolation level requires that you lock data that has been read but also data that doesn’t exist. Ex: if a SELECT returned no rows, you want it to return no. rows when the query is reissued. This is implemented in SQL Server by a special kind of lock called the key-range lock. Key-range locks require that there be an index on the column that defines the range of values. If there is no index on the column, serializable isolation requires a table lock. Gets its name from the fact that running multiple serializable transactions at the same time is equivalent of running them one at a time. Now that we understand the basics of what concurrency is, the subsequent blog posts will try to bring out the basics around locking, blocking, deadlocks because they are the fundamental blocks that make concurrency possible. Now if you are with me – let us continue learning for SQL Server Locking Basics. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Concurrency

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