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wcf中的使用全双工通信(转)
wcf中的契约通信默认是请求恢复的方式，当客户端发出请求后，一直到服务端回复时，才可以继续执行下面的代码。
除了使用请求应答方式的通信外，还可以使用全双工。下面给出例子：
1.添加一个wcf类库
2.在服务契约添加如下一个片段
[ServiceContract(Namespace = "http://Microsoft.ServiceModel.Samples", SessionMode = SessionMode.Required,
CallbackContract = typeof(ICalculatorDuplexCallback))]
public interface ICalculatorDuplex
{
[OperationContract(IsOneWay = true)]
void Clear();
[OperationContract(IsOneWay = true)]
void AddTo(double n);
[OperationContract(IsOneWay = true)]
void SubtractFrom(double n);
[OperationContract(IsOneWay = true)]
void MultiplyBy(double n);
[OperationContract(IsOneWay = true)]
void DivideBy(double n);
}
其中ICalculatorDuplexCallback为实现全双工客户端的接口
3.定义ICalculatorDuplexCallback接口。该接口目的主要是回调客户端的方法。和服务端无关，所以让该接口的方法设置为单向的
public interface ICalculatorDuplexCallback
{
[OperationContract(IsOneWay = true)]
void Equals(double result);
[OperationContract(IsOneWay = true)]
void Equation(string eqn);
}
4.由于回话是必须的，那么在契约实现的时候也要加上一个特性
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)]
public class Service1 : IService1
{
double result;
string equation;
ICalculatorDuplexCallback callback = null;
public Service1()
{
result = 0.0D;
equation = result.ToString();
callback = OperationContext.Current.GetCallbackChannel<ICalculatorDuplexCallback>();
}
public void Clear()
{
callback.Equation(equation + " = " + result.ToString());
result = 0.0D;
equation = result.ToString();
}
public void AddTo(double n)
{
result += n;
equation += " + " + n.ToString();
callback.Equals(result);
}
public void SubtractFrom(double n)
{
result -= n;
equation += " - " + n.ToString();
callback.Equals(result);
}
public void MultiplyBy(double n)
{
result *= n;
equation += " * " + n.ToString();
callback.Equals(result);
}
public void DivideBy(double n)
{
result /= n;
equation += " / " + n.ToString();
callback.Equals(result);
}
}
5.接着在项目中添加一个控制台程序，添加服务。服务会报异常
System.InvalidOperationException: 协定需要会话，但是绑定“BasicHttpBinding”不支持它或者因配置不正确而无法支持它。
在 System.ServiceModel.Description.DispatcherBuilder.BuildChannelListener(StuffPerListenUriInfo stuff, ServiceHostBase serviceHost, Uri listenUri, ListenUriMode listenUriMode, Boolean supportContextSession, IChannelListener& result)
在 System.ServiceModel.Description.DispatcherBuilder.InitializeServiceHost(ServiceDescription description, ServiceHostBase serviceHost)
在 System.ServiceModel.ServiceHostBase.InitializeRuntime()
在 System.ServiceModel.ServiceHostBase.OnOpen(TimeSpan timeout)
在 System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan timeout)
在 Microsoft.Tools.SvcHost.ServiceHostHelper.OpenService(ServiceInfo info)
需要把服务端配置文件中改一下：
<system.serviceModel>
<services>
<service name="WcfService1.Service1" behaviorConfiguration="WcfService1.Service1Behavior">
<!-- Service Endpoints -->
<!-- 除非完全限定，否则地址将与上面提供的基址相关 -->
<endpoint address="" binding="wsDualHttpBinding" contract="WcfService1.IService1">
<!--
部署时，应删除或替换下列标识元素，以反映
用来运行所部署服务的标识。删除之后，WCF 将
自动推断相应标识。
-->
<identity>
<dns value="http://www.mamicode.com/localhost"/>
</identity>
</endpoint>
<!-- Metadata Endpoints -->
<!-- 元数据交换终结点供相应的服务用于向客户端做自我介绍。 -->
<!-- 此终结点不使用安全绑定，应在部署前确保其安全或将其删除-->
<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
</service>
</services>
<behaviors>
<serviceBehaviors>
<behavior name="WcfService1.Service1Behavior">
<!-- 为避免泄漏元数据信息，
请在部署前将以下值设置为 false -->
<serviceMetadata httpGetEnabled="False" httpsGetEnabled="False"/>
<!-- 要接收故障异常详细信息以进行调试，
请将以下值设置为 true。在部署前设置为 false
以避免泄漏异常信息-->
<serviceDebug includeExceptionDetailInFaults="True" />
</behavior>
</serviceBehaviors>
</behaviors>
</system.serviceModel>
6.在控制台端，添加服务引用，实现服务定义的ICalculatorDuplexCallback接口（该接口自动生成的对应到服务引用中的IService1Callback）
public class CallbackHandler : IService1Callback
{
public void Equals(double result)
{
Console.WriteLine("Result({0})", result);
}
public void Equation(string eqn)
{
Console.WriteLine("Equation({0})", eqn);
}
}
7.在main函数中，去调用服务
InstanceContext instanceContext = new InstanceContext(new CallbackHandler());
// Create a client
ServiceReference1.Service1Client client = new ServiceReference1.Service1Client(instanceContext);
Console.WriteLine("Press <ENTER> to terminate client once the output is displayed.");
Console.WriteLine();
// Call the AddTo service operation.
double value = http://www.mamicode.com/100.00D;
client.AddTo(value);
// Call the SubtractFrom service operation.
value = http://www.mamicode.com/50.00D;
client.SubtractFrom(value);
// Call the MultiplyBy service operation.
value = http://www.mamicode.com/17.65D;
client.MultiplyBy(value);
// Call the DivideBy service operation.
value = http://www.mamicode.com/2.00D;
client.DivideBy(value);
// Complete equation
client.Clear();
Console.ReadLine();
//Closing the client gracefully closes the connection and cleans up resources
client.Close();
8.运行结果
