参考网址：https://www.cnblogs.com/scy251147/archive/2012/11/26/2789432.html
由于WCF中提供了CallbackContract属性，所以在双工通信中，我们可以很方便的和Server进行通信。虽然查遍了MSDN，也看过了它提供的例子，但是还是不知道怎么来使用(因为MSDN中只是给你提供了Server端的调用方法，并没有客户端的调用方式，所以例子没法儿跑起来，当然也就不能够从示例中看出CallbackContract属性的工作方式，鄙视下，呵呵)。在这篇文章中，我要做的就是让这个例子能够顺利地跑起来，从而了解CallbackContract的工作方式。
服务端编写
首先，创建一个名称为CallbackContractWCF的控制台项目，添加一个DuplexHello类作为我们的Service，具体代码就Copy了MSDN上面的：
using System;
using System.ServiceModel;
using System.Threading;
namespace CallbackContractWCF
{
[ServiceContract(Name = "SampleDuplexHello", CallbackContract = typeof(IHelloCallbackContract), SessionMode = SessionMode.Required)]
public interface IDuplexHello
{
[OperationContract(IsOneWay = true)]
void Hello(string greeting);
}
public interface IHelloCallbackContract
{
[OperationContract(IsOneWay = true)]
void Reply(string responseToGreeting);
}
public class DuplexHello:IDuplexHello
{
public DuplexHello()
{
Console.WriteLine("Service object created: " + this.GetHashCode().ToString());
}
~DuplexHello()
{
Console.WriteLine("Service object distroyed: " + this.GetHashCode().ToString());
}
public void Hello(string greeting)
{
Console.WriteLine("Caller sent: "+greeting);
Console.WriteLine("Session ID: "+OperationContext.Current.SessionId);
Console.WriteLine("Waiting two seconds before returning call.");
Thread.Sleep(2000);
IHelloCallbackContract callerProxy = OperationContext.Current.GetCallbackChannel<IHelloCallbackContract>();
string response = "Service object " + this.GetHashCode().ToString() + " received." + greeting;
Console.WriteLine("Sending back: " + response);
callerProxy.Reply(response);
}
}
}
using System;
using System.ServiceModel;
using System.Threading;
namespace CallbackContractWCF
{
[ServiceContract(Name = "SampleDuplexHello", CallbackContract = typeof(IHelloCallbackContract), SessionMode = SessionMode.Required)]
public interface IDuplexHello
{
[OperationContract(IsOneWay = true)]
void Hello(string greeting);
}
public interface IHelloCallbackContract
{
[OperationContract(IsOneWay = true)]
void Reply(string responseToGreeting);
}
public class DuplexHello:IDuplexHello
{
public DuplexHello()
{
Console.WriteLine("Service object created: " + this.GetHashCode().ToString());
}
~DuplexHello()
{
Console.WriteLine("Service object distroyed: " + this.GetHashCode().ToString());
}
public void Hello(string greeting)
{
Console.WriteLine("Caller sent: "+greeting);
Console.WriteLine("Session ID: "+OperationContext.Current.SessionId);
Console.WriteLine("Waiting two seconds before returning call.");
Thread.Sleep(2000);
IHelloCallbackContract callerProxy = OperationContext.Current.GetCallbackChannel<IHelloCallbackContract>();
string response = "Service object " + this.GetHashCode().ToString() + " received." + greeting;
Console.WriteLine("Sending back: " + response);
callerProxy.Reply(response);
}
}
}
从这个类中，我们可以看到它有一个IHelloCallbackContract的接口，由于它在ServiceContract中被标记为CallbackContract = typeof(IHelloCallbackContract)，所以它用于客户端回调。意即，服务端可以通过此接口中的方法将数据发送给客户端，客户端只需要实现此接口，即可接收到服务端发送过来的消息。
然后是创建配置文件，请参见我的文章：基于net.tcp的WCF配置实例解析。这里我们使用的EndPoint为：net.tcp://127.0.0.1/DuplexHello，创建好App.config配置文件后，拷贝到CallbackContractWCF项目下，然后打开Program.cs文件，编码以便让服务端能够启动监听：
using (ServiceHost host = new ServiceHost(typeof(DuplexHello)))
{
ServiceMetadataBehavior smb = host.Description.Behaviors.Find<ServiceMetadataBehavior>();
if (smb == null)
{
host.Description.Behaviors.Add(new ServiceMetadataBehavior());
}
//暴露MetaData，以便能够让SvcUtil.exe工具生成客户端代理类和配置文件
host.AddServiceEndpoint(typeof(IMetadataExchange), MetadataExchangeBindings.CreateMexTcpBinding(), "mex");
host.Open();
Console.WriteLine("service listen on endpoint ...");
Console.WriteLine("Press ENTER to stop ...");
Console.ReadLine();
host.Abort();
host.Close();
}
using (ServiceHost host = new ServiceHost(typeof(DuplexHello)))
{
ServiceMetadataBehavior smb = host.Description.Behaviors.Find<ServiceMetadataBehavior>();
if (smb == null)
{
host.Description.Behaviors.Add(new ServiceMetadataBehavior());
}
//暴露MetaData，以便能够让SvcUtil.exe工具生成客户端代理类和配置文件
host.AddServiceEndpoint(typeof(IMetadataExchange), MetadataExchangeBindings.CreateMexTcpBinding(), "mex");
host.Open();
Console.WriteLine("service listen on endpoint ...");
Console.WriteLine("Press ENTER to stop ...");
Console.ReadLine();
host.Abort();
host.Close();
}
好了，启动服务端，我们可以看到如下界面，服务端启动成功了：
客户端编写
下面开始来编写客户端。
首先打开SvcUtil.exe，按照文章：基于net.tcp的WCF配置实例解析 中介绍的方法，生成output.config文件和DuplexHello.cs代理类文件。
其次创建一个名称为CallbackContractWCFClient的Windows Form Application项目，将上面的两个文件拷贝进来，并修改output.config名称为App.config。
然后打开ClientForm窗体，继承自SampleDuplexHelloCallback接口(这个接口也就是服务端的IHelloCallbackContract接口的代理)，然后编写以下代码进行数据发送和接收：
using System;
using System.Windows.Forms;
using System.ServiceModel;
namespace CallbackContractWCFClient
{
public partial class ClientForm : Form, SampleDuplexHelloCallback
{
public ClientForm()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
InstanceContext site = new InstanceContext(this);
SampleDuplexHelloClient client = new SampleDuplexHelloClient(site);
string msg =" This is a Client Message sent to Server side...";
label1.Text = "Client Sent: " + msg;
client.Hello(msg);
}
public void Reply(string responseToGreeting)
{
label2.Text = "Server Reply: " + responseToGreeting;
}
}
}
using System;
using System.Windows.Forms;
using System.ServiceModel;
namespace CallbackContractWCFClient
{
public partial class ClientForm : Form, SampleDuplexHelloCallback
{
public ClientForm()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
InstanceContext site = new InstanceContext(this);
SampleDuplexHelloClient client = new SampleDuplexHelloClient(site);
string msg =" This is a Client Message sent to Server side...";
label1.Text = "Client Sent: " + msg;
client.Hello(msg);
}
public void Reply(string responseToGreeting)
{
label2.Text = "Server Reply: " + responseToGreeting;
}
}
}
这样，我们的服务端和客户端就写好了，接下来运行，结果显示如下：
服务端：
客户端：
源码下载
分类: WCF 点滴记录