（本文原作于2006.03.14，第一次修正于2006.06.06，修正后适用于ESFramework V0.3+）
本来
Tcp/udp
组件是系统与外界交换消息的唯一进出口，而
Tcp
组件或
Udp
组件与我们系统唯一的联系是通过消息分派器IMessageDispatcher，如此一来，就相当于
ESFramework
规定了消息分派器是我们应用与外界交换消息的进出口。IMessageDispatcher是与协议无关、宿主无关的组件，即，它即可以在使用于TCP协议也可使用于Udp协议，如果使用Remoting的方式通信也可以使用IMessageDispatcher来分派消息；它即可以用在服务端也可以用于客户端，这样的高可复用性使得基于不同底层（如Tcp/Udp、服务端/客户端）构建的上层应用具有高度的统一性，同时使得ESFramework的整个架构更加清晰、学习曲线更平滑。
IMessageDispatcher保证接收到的每个消息和发送出去的每个消息都能被所有的
Hook
和
Spy
所
截获。另外，消息分派器可能需要验证接收到的每个消息格式是否正确、消息是否合法、消息是否符合特定规格等。下面是消息分派器组件的组成：
消息分派器
IMessageDispatcher
定义如下：
{
IEsbLoggerEsbLogger{ set ;}
INetMessageHookNetMessageHook{ set ;} // 可为EsbNetMessageHook
IGatewayMessageSpyGatewayMessageSpy{ set ;}
IInnerMessageSpyInnerMessageSpy{ set ;}
IContractHelperContractHelper{ set ;} // 必须设置
INakeDispatcherNakeDispatcher{ set ;} // 必须设置
NetMessageDispatchMessage(NetMessagereqMsg);
/// <summary>
/// 如所有的SingleMessage在发送之前必须经过IMessageDispatcher的Hook链和Spy
/// </summary>
NetMessageBeforeSendMessage(NetMessagemsg);
event CbNetMessageMessageReceived;
}
从
IMessageDispatcher的组件结构图和
接口的定义可以看出，
IMessageDispatcher保证了将接受到的消息按照规定的顺序经过各个Spy、Hook、消息处理器等组件。任何消息不得例外。即使是系统内部生成的消息（如发给客户端的通知），也必须经过
IMessageDispatcher的BeforeSendMessage后才可安全的发送出去。
IMessageDispatcher的实现如下所示：
{
#region property
#region Logger
private IEsbLoggeresbLogger = new EmptyEsbLogger();
public IEsbLoggerEsbLogger
{
set
{
if (value != null )
{
this .esbLogger = value;
}
}
}
#endregion
#region NakeDispatcher
private INakeDispatchernakeDispatcher;
public INakeDispatcherNakeDispatcher
{
set
{
this .nakeDispatcher = value;
}
}
#endregion
#region NetMessageHook
private INetMessageHooknetMessageHook = new EmptyNetMessageHook();
public INetMessageHookNetMessageHook
{
set
{
this .netMessageHook = value;
}
}
#endregion
#region InnerMessageSpy
private IInnerMessageSpyinnerMessageSpy = new EmptyInnerMessageSpy();
public IInnerMessageSpyInnerMessageSpy
{
set
{
if (value != null )
{
this .innerMessageSpy = value;
}
}
}
#endregion
#region GatewayMessageSpy
private IGatewayMessageSpygatewayMessageSpy = new EmptyGatewayNetMessageSpy();
public IGatewayMessageSpyGatewayMessageSpy
{
set
{
if (value != null )
{
this .gatewayMessageSpy = value;
}
}
}
#endregion
#region ContractHelper
private IContractHelpercontractHelper = null ;
public IContractHelperContractHelper
{
set
{
this .contractHelper = value;
}
}
#endregion
public event CbNetMessageMessageReceived;
#endregion
#region IMessageDispatcher成员
public NetMessageDispatchMessage(NetMessagereqMsg)
{
try
{
if ( this .MessageReceived != null )
{
this .MessageReceived(reqMsg);
}
this .gatewayMessageSpy.SpyReceivedMsg(reqMsg);
NetMessagemsgHooked = this .netMessageHook.CaptureReceivedMsg(reqMsg);
this .innerMessageSpy.SpyReceivedMsg(msgHooked);
NetMessageresMsg = this .nakeDispatcher.DispatchMessage(msgHooked);
if (reqMsg == null )
{
return null ;
}
return this .BeforeSendMessage(resMsg);
}
catch (Exceptionee)
{
this .esbLogger.Log(ee.GetType().ToString(),ee.Message, " ESFramework.Network.MessageDispatcher.DispatchMessage " ,ErrorLevel.High);
return this .contractHelper.GetResponseByServiceResultType(reqMsg,ServiceResultType.HandleFailure);
}
}
public NetMessageBeforeSendMessage(NetMessagemsg)
{
this .innerMessageSpy.SpyToBeSendedMsg(msg);
NetMessagemsgHooked = this .netMessageHook.CaptureBeforeSendMsg(msg);
this .gatewayMessageSpy.SpyToBeSendedMsg(msgHooked);
return msgHooked;
}
#endregion
}
我们看到，
IMessageDispatcher内部使用了INakeDispatcher组件，INakeDispatcher的职责比较单纯，它针对需要分派的消息调用IDataDealerFactory创建对应的处理器，然后将消息交给处理器处理后，将结果返回。其接口定义如下：
{
NetMessageDispatchMessage(NetMessagemsg);
}
INakeDispatcher的实现也非常简单：
{
#region DataDealerFactory
private IDataDealerFactorydataDealerFactory = null ;
public IDataDealerFactoryDataDealerFactory
{
set
{
this .dataDealerFactory = value;
}
}
#endregion
#region ContractHelper
private IContractHelpercontractHelper = null ;
public IContractHelperContractHelper
{
set
{
this .contractHelper = value;
}
}
#endregion
#region INakeDispatcher成员
public NetMessageDispatchMessage(NetMessagemsg)
{
IDataDealerdealer = this .dataDealerFactory.CreateDealer(msg.Header.ServiceKey,msg.Header.TypeKey);
if (dealer == null )
{
return this .contractHelper.GetResponseByServiceResultType(msg,ServiceResultType.ServiceIsNotExist);
}
return dealer.DealRequestMessage(msg);
}
#endregion
}
通常，在客户端使用IMessageDispatcher组件时，我们不需要使用GatewayMessageSpy和InnerMessageSpy，如果是这样，那么我们只要不为MessageDispatcher的
GatewayMessageSpy属性和InnerMessageSpy属性注入对象就可以了。
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ESFramework介绍之（4）――消息拦截器INetMessageHook
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ESFramework 可复用的通信框架（序）
