WCF(三) Message pattern

上次咱们稍稍讨论了WCF中的contract,这次咱们讨论Message Pattern.

WCF中为何会有message pattern呢?

我们知道WCF的Server端与client端是通过xml 来进行交互的.message pattern其实就是指server端与client端交互xml的方式.

wcf提供以下三种pattern:

1.Request-reply:client端调用server端的公开的method后,client端需等server端method返回结果(即:reply响应)以后,才能做继续client端的下一步操作.(如:client调用server端的method往数据库中插入一条数据.server端插入数据成功以后,返回相应的数据库插入成功信息.很多情况下使用的是这种.

2.one-way:client端调用server端的公开的method后,client端不需等server端的method返回结果,便可继续client端下一步操作.(如:server端记录client端的日志(log)信息).标识为One-way的operation(函数)的返回值只能是void. 当client向server 发起了request后,不需要server做出回应的情况使用one-way message pattern.

3.duplicate:Request-Reply 和One-way都是先由client端发起的request(请求);duplicate则允许有server端发起request.

两种方式实现duplicate:一种是tcp(这里先不讲tcp的方式,先讲http的方式).一种是http. Http方式的话:是先由client端发起一次one-way 的request,然后client不等待server端返回结果,而是端继续往下执行.当server端有结果返回时,再有server端发起一次one-way的request.所以duplicate也叫callback. 我们知道当一个操作很费时的话,为了减少UI的无响应,有更好的用户体验,会使用callback.wcf也是:当server的执行很耗时的话,我们可以使用duplicate的message pattern.

4.实现:

4.1:Requst-Reply:是最简单的

    [ServiceContract(CallbackContract = typeof(IDuplicateDemoCallback))]
    public interface IService1
    {
        // 在函数中,我们让线程暂停,模拟耗时的操作.
        // 参数:interval为暂停的毫秒数,由调用该method的client端设定.
        [OperationContract]
        void RequestReply(int interval);

        [OperationContract]
        void DuplicateCommunicate(int interval);

    }

4.2:One-Way:(只需要在requst-reply的基础上,使operationContract 的IsOneWay=true即可)

    [ServiceContract(CallbackContract = typeof(IDuplicateDemoCallback))]
    public interface IService1
    {
        // 在函数中,我们让线程暂停,模拟耗时的操作.
        // 参数:interval为暂停的毫秒数,由调用该method的client端设定.
        [OperationContract(IsOneWay = true)]
        void RequestReply(int interval);

        [OperationContract(IsOneWay = true)]
        void DuplicateCommunicate(int interval);

    }

4.3Duplicate:(有些复杂)有以下步骤:
4.3.1:在server端IService.cs文件中添加代码:

    // NOTE: You can use the "Rename" command on the "Refactor" menu to change the interface name "IService1" in both code and config file together.
    [ServiceContract(CallbackContract = typeof(IDuplicateDemoCallback))]
    public interface IService1
    {
        // 在函数中,我们让线程暂停,模拟耗时的操作.
        // 参数:interval为暂停的毫秒数,由调用该method的client端设定.
        [OperationContract(IsOneWay=true)]
        void RequestReply(int interval);
       
        [OperationContract(IsOneWay=true)]
        void DuplicateCommunicate(int interval);


    }

    public interface IDuplicateDemoCallback
    {
        [OperationContract(IsOneWay=true)]
        void DuplicateCommunicateCallback(string callbackMessage);
    }

4.3.2:在web site项目下的web.config文件:使其支持wsDua

<?xml version="1.0"?>
<configuration>

  <system.web>
    <compilation debug="false" targetFramework="4.0" />
  </system.web>
  <system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment -->
          <serviceMetadata httpGetEnabled="true"/>
          <!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information -->
          <serviceDebug includeExceptionDetailInFaults="false"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <serviceHostingEnvironment multipleSiteBindingsEnabled="true" />

    <services>
      <service name="WcfMessagePatternLib.Service1" behaviorConfiguration="">
        <!-- Service Endpoints -->
        <endpoint address="" binding="wsDualHttpBinding" contract="WcfMessagePatternLib.IService1">     
          <identity>
            <dns value="localhost"/>
          </identity>
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
      </service>
    </services>
    
    
    </system.serviceModel>
  <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
  </system.webServer>
  
</configuration>

4.3.3在client端添加一个类文件命名为Callback.cs:
使其实现IDuplicateDemoCallback接口.

    class Callback:ServiceReference1.IService1Callback
    {
        public void DuplicateCommunicateCallback(string callbackMessage)
        {
            MessageBox.Show(callbackMessage);
        }
    }

        private void Form1_Load(object sender, EventArgs e)
        {
            var context = new InstanceContext(new Callback());
            proxy = new Service1Client(context);
        }

 4.3.4修改client项目下的app.config文件:使其支持wsdualhttp

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <system.serviceModel>
        <bindings>
            <wsDualHttpBinding>
                <binding name="WSDualHttpBinding_IService1" closeTimeout="00:01:00"
                    openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00"
                    bypassProxyOnLocal="false" transactionFlow="false" hostNameComparisonMode="StrongWildcard"
                    maxBufferPoolSize="524288" maxReceivedMessageSize="65536"
                    messageEncoding="Text" textEncoding="utf-8" useDefaultWebProxy="true">
                    <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384"
                        maxBytesPerRead="4096" maxNameTableCharCount="16384" />
                    <reliableSession ordered="true" inactivityTimeout="00:10:00" />
                    <security mode="Message">
                        <message clientCredentialType="Windows" negotiateServiceCredential="true"
                            algorithmSuite="Default" />
                    </security>
                </binding>
            </wsDualHttpBinding>
        </bindings>
        <client>
            <endpoint address="http://localhost:8167/WebHost/Service.svc"
                binding="wsDualHttpBinding" bindingConfiguration="WSDualHttpBinding_IService1"
                contract="ServiceReference1.IService1" name="WSDualHttpBinding_IService1">
                <identity>
                    <dns value="localhost" />
                </identity>
            </endpoint>
        </client>
    </system.serviceModel>
</configuration>