Remoting的事件机制（带具体例子）

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。