WCF热门问题编程示例(5):WCF服务如何获取客户端在线用户数量？

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;
using System.ServiceModel.Description;
using System.Runtime.Serialization;
using System.Threading;
//ServiceContract 属性以及 Indigo 使用的所有其他属性均在 System.ServiceModel 命名空间中定义，
//因此本例开头使用 using 语句来引用该命名空间。
namespace WCFService
{
//1.回调服务契约，由于回调方法在客户端执行，因此无须添加 ServiceContractAttribute。对于回调操作，服务器无须获取其返回信息，因此添加 IsOneWay=true 特性参数。
public interface IWCFServiceCallBack
{
//操作契约
[OperationContract(IsOneWay=true)]//
void SayHelloCalllBack();
}
//2.服务契约,指定 CallbackContract 回调契约。
[ServiceContract(CallbackContract = typeof(IWCFServiceCallBack))]
public interface IWCFService
{
//操作契约，
[OperationContract]
string SayHelloToUser(string name);

}
//3.服务类，继承接口。实现服务契约定义的操作
public class WCFService : IWCFService
{
//回调通道列表，也可以用来保持
private static List<IWCFServiceCallBack> channelsList = new List<IWCFServiceCallBack>();
private static Object thisLock = new Object();

public WCFService()
{
Console.WriteLine("constructed! {0} , …", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"));
}
//实现接口定义的方法
public string SayHelloToUser(string name)
{
Console.WriteLine("Begin Call at {0} , …", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"));
//获取当前操作客户端对象实例
IWCFServiceCallBack callback = OperationContext.Current.GetCallbackChannel<IWCFServiceCallBack>();
//绑定事件方法
OperationContext.Current.Channel.Closed += new EventHandler(ShowOffLine);
//OperationContext.Current.Channel.Faulted += new EventHandler(ShowOffLine);
//添加回调通道
lock (thisLock)
{
channelsList.Add(callback);
}
callback.SayHelloCalllBack();
Console.WriteLine("End Call at {0} , …", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"));
return "Hello! " + name;
}

private void ShowOffLine(object sender, EventArgs e)
{
IWCFServiceCallBack callback = sender as IWCFServiceCallBack;
lock (thisLock)
{
channelsList.Remove(callback);
Console.WriteLine("OffLine! {0} , current clients are {1}", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"), channelsList.Count);
}
}
}
}

//CallBack 回调服务
Console.WriteLine("Call Back Operation Test…");
for (int i = 0;i < 10;i++)
{
IWCFServiceCallback callBack = new WCFServiceCallback();
InstanceContext context = new InstanceContext(callBack);
WCFServiceClient WCFServiceCallBackClientProxy = new WCFServiceClient(context, "NetTcpBinding_IWCFService");
//通过代理调用调用SayHelloToUser,传递对象
WCFServiceCallBackClientProxy.SayHelloToUser("Frank Xu Lei Call Back");
}
//For Debug
Console.WriteLine("Press any key to continue…");
Console.Read();