一步一步学Remoting之六：事件（1）

概念就不说了，具体参见msdn相关章节：
http://msdn.microsoft.com/library/CHS/cpguide/html/cpconEvents.asp

我们先来改造一下上次的程序，为上次的主线程方法添加事件，能不断的引发事件来汇报处理的进度：

public class MyEventArgs
{
    private int _rate;
    
    public int Rate
    {
        get
        {
            return _rate;
        }
    }

    public MyEventArgs(int rate)
    {
        this._rate=rate;
    }
}

public class MyObject
{
    public delegate void MyEventHandler(object sender,MyEventArgs e);
    public event MyEventHandler MyEvent;

    public void ALongTimeMethod(int time)
    {
        Console.WriteLine("主线程方法开始");
        for(int i=0;i<100;i++)
        {
            System.Threading.Thread.Sleep(time);
            OnMyEvent(new MyEventArgs(i));
        }
        Console.WriteLine("主线程方法结束");
    }

    protected void OnMyEvent(MyEventArgs e)
    {
        if (MyEvent!=null)
        {
            MyEvent(this,e);
        }
    }
}

再来为事件添加处理程序：

class MyClient
{
    [STAThread]
    static void Main(string[] args)
    {
        DateTime dt=DateTime.Now;
        MyObject obj=new MyObject();
        obj.MyEvent+=new MyObject.MyEventHandler(obj_MyEvent);
        obj.ALongTimeMethod(50);
        Console.WriteLine("用了"+((TimeSpan)(DateTime.Now-dt)).TotalSeconds+"秒");
        Console.ReadLine();
    }

    public static void obj_MyEvent(object sender,MyEventArgs e)
    {
        Console.WriteLine("主线程方法完成了"+e.Rate+"%");
    } 
}
运行程序可以看到： 
 

这个是本地的，远程对象的事件也这么简单吗？其实没有想象的简单，因为对象是在远程的，服务端的事件客户端怎么捕捉？应该说远程对象的事件可以分成客户端触发－》服务器应答，服务端触发－》客户端应答和客户端触发－》客户端应答，第一种就很简单了，后面2种都需要有一个中间件。下面我们来要为程对象同样来添加一个进度机制，首先来建立我们的远程对象：

[Serializable]
    public class MyEventArgs:EventArgs
    {
        private int _rate;
        private string _ip;

        public int Rate
        {
            get
            {
                return _rate;
            }
        }

        public string IP
        {
            get
            {
                return _ip;
            }
        }

        public MyEventArgs(int rate,string ip)
        {
            this._rate=rate;
            this._ip=ip;
        }
    }

    public class MyObject:MarshalByRefObject
    {
        public delegate void MyEventHandler(object sender,MyEventArgs e);
        public event MyEventHandler MyEvent;

        public int ALongTimeMethod(int a,int b,int time,string ip)
        {
            Console.WriteLine("异步方法开始");
            for(int i=0;i<10;i++)
            {
                System.Threading.Thread.Sleep(time);
                OnMyEvent(new MyEventArgs(i,ip));
            }
            Console.WriteLine("异步方法结束");
            return a+b;
        }

        protected void OnMyEvent(MyEventArgs e)
        {
            if (MyEvent!=null)
            {
                MyEvent(this,e);
            }
        }
    }
为了调试方便，服务器端和客户端这次都用程序实现，下面是服务器端：
using System;
using System.Collections;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Channels;
using System.Runtime.Remoting.Channels.Tcp;
using System.Runtime.Serialization.Formatters;

namespace RemoteServer
{
    class MyServer
    {
        [STAThread]
        static void Main(string[] args)
        {
            RemotingConfiguration.RegisterWellKnownServiceType(typeof(RemoteObject.MyObject),"RemoteObject.MyObject",WellKnownObjectMode.Singleton);
            BinaryServerFormatterSinkProvider serverProvider = new BinaryServerFormatterSinkProvider(); 
            BinaryClientFormatterSinkProvider clientProvider = new BinaryClientFormatterSinkProvider(); 
            serverProvider.TypeFilterLevel = TypeFilterLevel.Full; 
            IDictionary props = new Hashtable(); 
            props["port"]=9999; 
            TcpChannel channel = new TcpChannel(props,clientProvider,serverProvider); 
            ChannelServices.RegisterChannel(channel); 
            Console.ReadLine();
        }
    }
}
客户端为了简单一点，我去除了前面做测试的本地事件：
using System;
using System.Net;
using System.Collections;
using System.Text;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Channels;
using System.Runtime.Remoting.Channels.Tcp;
using System.Runtime.Serialization.Formatters;

class MyClient
{
    private delegate int MyDelegate(int a,int b,int time,string ip);
    private static MyDelegate md;

    [STAThread]
    static void Main(string[] args)
    {
        DateTime dt=DateTime.Now;
        RemotingConfiguration.RegisterWellKnownClientType(typeof(RemoteObject.MyObject), "tcp://localhost:9999/RemoteObject.MyObject");
        BinaryServerFormatterSinkProvider serverProvider = new BinaryServerFormatterSinkProvider(); 
        BinaryClientFormatterSinkProvider clientProvider = new BinaryClientFormatterSinkProvider(); 
        serverProvider.TypeFilterLevel = TypeFilterLevel.Full; 
        IDictionary props=new Hashtable(); 
        props["port"]=0; 
        TcpChannel channel = new TcpChannel(props,clientProvider,serverProvider); 
        ChannelServices.RegisterChannel(channel); 
        RemoteObject.MyObject app=new RemoteObject.MyObject();
        app.MyEvent+=new RemoteObject.MyObject.MyEventHandler(MyEvent);
        md=new MyDelegate(app.ALongTimeMethod);
        AsyncCallback ac=new AsyncCallback(MyClient.CallBack);
        IPHostEntry ipHE=Dns.GetHostByName(Dns.GetHostName());
        IAsyncResult Iar=md.BeginInvoke(1,2,300,ipHE.AddressList[0].ToString(),ac,null);
        Method();
        Console.WriteLine("用了"+((TimeSpan)(DateTime.Now-dt)).TotalSeconds+"秒");
        ChannelServices.UnregisterChannel(channel);
        Console.ReadLine();
    }

    public static void CallBack(IAsyncResult Iar)
    {
        if(Iar.IsCompleted)
        {
            Console.WriteLine("结果是"+md.EndInvoke(Iar));
        }
    }

    public static void MyEvent(object sender,RemoteObject.MyEventArgs e)
    {
        Console.WriteLine("来自"+e.IP+"的异步方法完成了"+e.Rate*10+"%");
    } 

    public static void Method()
    {
        Console.WriteLine("主线程方法开始");
        System.Threading.Thread.Sleep(5000);
        Console.WriteLine("主线程方法结束");
    }
}

代码看上去不错，可是debug启动后报错： 
 
这就是我前面提到的问题，远程不可能有本地的程序集，也无法触发本地事件。解决办法就是加一个事件中间件，继承MarshalByRefObject：
public class EventClass:MarshalByRefObject
    {
        public void MyEvent(object sender,MyEventArgs e)
        {
            Console.WriteLine("来自"+e.IP+"的异步方法完成了"+e.Rate*10+"%");
        } 
    }
然后来修改一下客户端：
把app.MyEvent+=new RemoteObject.MyObject.MyEventHandler(MyEvent);修改为
RemoteObject.EventClass ec=new RemoteObject.EventClass();
        app.MyEvent+=new RemoteObject.MyObject.MyEventHandler(ec.MyEvent); 删除客户端的MyEvent静态方法。

运行一下程序： 
 

前后两个窗口本别是服务端和客户端的，貌似达到了我们的要求，其实不然，程序有2个漏洞：
1、客户端关闭以后打开新的程序就出错，因为以前的委托链丢失，服务端程序企图触发事件出错。
2、同时打开几个客户端，客户端收到的是所有的进度信息，而不仅仅是自己的，广播性质的消息。