[WCF学习笔记] Endpoint

WCF提供了一个框架/平台来构建分布的互联系统，WCF是SOA的，是面向服务的。但一个Service必须至少包含一个Endpoint，否则，试想一下，客户端连到哪里来获得一个Service？一个服务(Service)必须告诉外部在某个Endpoint提供什么和沟通什么。换句话说：“服务就是: 在某个地方、使用某种通讯协议、传输某种数据类型的消息”。

客户只能通过服务的Endpoint来访问服务。每个Endpoint必须包含地址、绑定和协议（契约）, host 进程会提供 Endpoint 供客户端调用。一个服务至少包含一个Endpoint，可以有多个Endpoint，多个绑定和多个契约。多个 Endpoint 可以共享相同的绑定和契约，每个服务又可以提供多个 Endpoint 供客户端掉用。每个Endpoint用唯一的地址(Address)来区分于其它的Endpoint，绑定指定了服务与外部通讯的方式( 例如 NetTcp, MSMQ等等)，而契约指定了消息格式、Endpoint会发生的行为具体提供什么服务，Service behaviour可以控制服务的运行时特性( 例如 线程问题，service实例管理等)。当服务收到一条消息，服务开始执行。一个服务的描述和实现代码的CLR runtime instance被创建。WCF运行时(WCF Runtime)控制消息的格式化，消息的收发等等。

• Address: WCF提供服务的地址，每个Endpoint的地址是唯一的；Address可以是http://mymachine:8080/myservice，也可以是Net.tcp://localhost:8000/WCFService/tcpmex。Address类型有：Endpoint address / Base address / MEX address。
• Binging: 指定通信协议和安全方式，例如 Http，NetTcp, MSMQ等等。默认提供的9种见下图。
• Contract: 具体这个服务提供什么功能，Client和Server交互的输入输入，消息格式，其它约定等。
• Behaviour: 可以控制服务的运行时特性( 例如 线程问题，service实例管理等)。分两类：service behaviors / operation behaviors。这些行为，或特性，可以通过配置runtime属性配置文件，或自定义行为来实现。

[OperationBehavior] 特性

• AddressFilterMode
• AutomaticSessionShutdown
• ConcurrencyMode
• ConfigurationName
• IgnoreExtensionDataObject
• IncludeExceptionDetailInFaults
• InstanceContextMode
• ReleaseServiceInstanceOnTransactionComplete
• TransactionAutoCompleteOnSessionClose
• TransactionIsolationLevel
• TransactionTimeout
• UseSynchronizedContext
• ValidateMustUnderstand

[OperationBehavior] 特性

• AutoDisposeParameters
• Impersonation
• ReleaseInstanceMode
• TransactionAutoComplete
• TransactionScopeRequired

WCF Contract 三种基本契约类型:

• Service Contract:(WSDL) 定义服务方法，也就是说，对客户端来说，在某个Endpoint什么操作或服务可用.
• Data Contract: (XSD) 定义服务方法的数据类型.
• Message Contract: (SOAP) 在创建消息的时候控制消息头.

例子：

using System;

using System.ServiceModel;

using System.Collections.Generic;

using System.Runtime.Serialization;

using System.IO;

namespace WCFService

{

  [ServiceContract]

  public interface IServiceClass

  {

    [OperationContract]

    ExplicitNumbers Add(ExplicitNumbers en1, ExplicitNumbers en2);

    [OperationContract]

    ExplicitNumbers Subtract(ExplicitNumbers en1, ExplicitNumbers en2);

  }

  [DataContract]

  public class ExplicitNumbers

  {

    [DataMember]

    public double Explicit1;

    [DataMember]

    public double Explicit2;    

    public ExplicitNumbers(double explicit1, double explicit2)

    {

       this.Explicit1 = explicit1;

       this.Explicit2 = explicit2;

    }

  }

  public class ServiceClass : IServiceClass

  {

     public ExplicitNumbers Add(ExplicitNumbers en1, ExplicitNumbers en2)

     {

        return new ExplicitNumbers(en1.Explicit1 + en2.Explicit1, en1.Explicit2 + en2.Explicit2);

     }

     public ExplicitNumbers Subtract(ExplicitNumbers en1, ExplicitNumbers en2)

     {

        return new ExplicitNumbers(en1.Explicit1 - en2.Explicit1, en1.Explicit2 - en2.Explicit2);

     }

  }

}

<?xml version=”1.0” encoding=”utf-8” ?>

<configuration>

  <system.serviceModel>

     <services>

        <service name =”WCFService.ServiceClass” behaviorConfiguration=”metadataSupport”>

           <host>

             <baseAddresses>

                 <add baseAddress=”http://localhost:8080/WCFService”/>

                 <add baseAddress=”net.pipe://localhost/WCFService”/>

                 <add baseAddress=”net.tcp://localhost:8000/WCFService”/>

             </baseAddresses>

           </host>

           <endpoint address=”” binding=”wsHttpBinding” contract=”WCFService.IServiceClass”/>

           <endpoint address=”tcpmex” binding=”mexTcpBinding” contract=”IMetadataExchange”/>

           <endpoint address=”namedpipemex” binding=”mexNamedPipeBinding” contract=”IMetadataExchange”/>

        </service>

     </services>

     <behaviors>

        <serviceBehaviors>

          <behavior name=”metadataSupport”>

             <serviceMetadata httpGetEnabled=”false” httpGetUrl=””/>

          </behavior>

        </serviceBehaviors>

     </behaviors>

  </system.serviceModel>

</configuration>

WCF默认提供的9种Binding类型：

Endpoint可以通过代码定义:

Uri bpa = new Uri(“net.pipe://localhost/NetNamedPipeBinding”);

Uri tcpa = new Uri(“net.tcp://localhost:8000/TcpBinding”);

sh = new ServiceHost(typeof(ServiceClass), bpa, tcpa);

NetNamedPipeBinding pb = new NetNamedPipeBinding();

NetTcpBinding tcpb = new NetTcpBinding();

ServiceMetadataBehavior mBehave = new ServiceMetadataBehavior();

sh.Description.Behaviors.Add(mBehave);

sh.AddServiceEndpoint(typeof(IMetadataExchange),

  MetadataExchangeBindings.CreateMexTcpBinding(), “mex”);

sh.AddServiceEndpoint(typeof(IMetadataExchange),

  MetadataExchangeBindings.CreateMexNamedPipeBinding(), “mex”);

sh.AddServiceEndpoint(typeof(IServiceClass), pb, bpa);

sh.AddServiceEndpoint(typeof(IServiceClass), tcpb, tcpa);

sh.Open();

Endpoint可以通过配置文件定义:

<?xml version=”1.0” encoding=”utf-8” ?>

<configuration>

 <system.serviceModel>

     <services>

        <service name =”WCFService.ServiceClass” behaviorConfiguration=”metadataSupport”>

           <host>

             <baseAddresses>

               <add baseAddress=”net.pipe://localhost/WCFService”/>

               <add baseAddress=”net.tcp://localhost:8000/WCFService”/>

               <add baseAddress=”http://localhost:8080/WCFService”/>

             </baseAddresses>

           </host>

           <endpoint address=”tcpmex” binding=”mexTcpBinding” contract=”IMetadataExchange”/>

           <endpoint address=”namedpipemex” binding=”mexNamedPipeBinding” contract=”IMetadataExchange”/>

           <endpoint address=”” binding=”wsHttpBinding” contract=”WCFService.IServiceClass”/>

        </service>

     </services>

     <behaviors>

       <serviceBehaviors>

          <behavior name=”metadataSupport”>

             <serviceMetadata httpGetEnabled=”false” httpGetUrl=””/>

          </behavior>

       </serviceBehaviors>

     </behaviors>

 </system.serviceModel>

</configuration>

Endpoint可以通过配置文件定义行为( Behaviour )：

<?xml version=”1.0” encoding=”utf-8” ?>

<configuration>

<system.serviceModel>

  <services>

     <service name =”WCFService.ServiceClass” behaviorConfiguration=”metadataSupport”>

         <host>

            <baseAddresses>

               <add baseAddress=”net.pipe://localhost/WCFService”/>

               <add baseAddress=”net.tcp://localhost:8000/WCFService”/>

               <add baseAddress=”http://localhost:8080/WCFService”/>

            </baseAddresses>

         </host>

         <endpoint address=”tcpmex” binding=”mexTcpBinding” contract=”IMetadataExchange”/>

         <endpoint address=”namedpipemex” binding=”mexNamedPipeBinding” contract=”IMetadataExchange”/>

         <endpoint address=”” binding=”wsDualHttpBinding” contract=”WCFService.IServiceClass”/>

         <!--<endpoint address=”mex” binding=”mexHttpBinding” contract=”IMetadataExchange”/>-->

     </service>

  </services>

  <behaviors>

    <serviceBehaviors>

      <behavior name=”metadataSupport”>

        <serviceDebug includeExceptionDetailInFaults=”true”/>

        <serviceMetadata httpGetEnabled=”false” httpGetUrl=””/>

        <serviceThrottling maxConcurrentCalls=”10” maxConcurrentInstances=”5” maxConcurrentSessions=”5”/>

        <serviceSecurityAudit auditLogLocation=”Application” suppressAuditFailure=”false”/>

      </behavior>

    </serviceBehaviors>

  </behaviors>

</system.serviceModel>

</configuration>

Links:

[WCF学习笔记] Binding

[WCF学习笔记] Hosting