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的Binding换成
<endpoint address="" binding="BasicHttpBinding" contract="WcfServiceLibrary1.IService1">
<endpoint address="" binding="wsDualHttpBinding" contract="WcfServiceLibrary1.IService1">
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 = 100.00D;
client.AddTo(value);
// Call the SubtractFrom service operation.
value = 50.00D;
client.SubtractFrom(value);
// Call the MultiplyBy service operation.
value = 17.65D;
client.MultiplyBy(value);
// Call the DivideBy service operation.
value = 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
9.源码
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public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { MyData aData = new MyData(); InstanceContext instanceContext = new InstanceContext(new CallbackHandler(aData)); // 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 = 100.00D; client.AddTo(value); double a = aData.Datadouble; //MessageBox.Show(a.ToString()); // Call the SubtractFrom service operation. value = 50.00D; client.SubtractFrom(value); // Call the MultiplyBy service operation. value = 17.65D; client.MultiplyBy(value); // Call the DivideBy service operation. value = 2.00D; client.DivideBy(value); // Complete equation client.Clear(); } } public class CallbackHandler :ServiceReference1.IService1Callback { MyData data = null; public CallbackHandler(MyData aData) { data = aData; } public void Equals(double result) { data.Datadouble = result; //Console.WriteLine("Result({0})", result); } public void Equation(string eqn) { data.DataString = eqn; //Console.WriteLine("Equation({0})", eqn); } } public class MyData { public double Datadouble { get; set; } public string DataString { get; set; } } |