Remoting的事件机制(带具体例子)

王朝other·作者佚名  2006-05-14
窄屏简体版  字體: |||超大  

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。

 
 
 
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