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我的WCF之旅(13)：创建基于MSMQ的Responsive Service

2007-07-01 16:06 1161 查看

一、One-way MEP V.S. Responsible Service
我们知道MSMQ天生就具有异步的特性，它只能以One-way的MEP（Message Exchange Pattern）进行通信。Client和Service之间采用One-way MEP的话就意味着Client调用Service之后立即返回，它无法获得Service的执行结果，也无法捕捉Service运行的Exception。下图简单表述了基于MSMQ的WCF Service中Client和Service的交互。

namespace Artech.ResponsiveQueuedService.Contract
现在变成：

namespace Artech.ResponsiveQueuedService.Contract

虽然这种方式看起来不错，但是却不值得推荐。在一般情况下，我们的Contract需要是很稳定的，一经确定就不能轻易更改，因为Contract是被交互的多方共同支持的，牵一发动全身；此外，从Service Contract代表的是Service的一个Interface，他是对业务逻辑的抽象、和具体实现无关，而对于我们的例子来说，我们仅仅是定义一个递交Order的Operation，从业务逻辑来看，OrderResponseContext和抽象的业务逻辑毫无关系。基于此，我们需要寻求一种和Service Contract无关的解决方式：

方式二、将OrderResponseContext放到Soap Message 的Header中

其实我们要解决的问题很简单，就是要把OrderResponseContext的信息置于Soap Message中发送到Service。而我们知道，Soap的Header具有极强的可伸缩性，原则上，我们可以把任何控制信息置于Header中。基于WCF的编程模式很容易地帮助我们实现对Soap Header的插入和获取：

我们可以通过下面的方式获得当前Operation Context的Incoming Message Headers和Outgoing Message Headers

OperationContext.Current.IncomingMessageHeaders
OperationContext.Current.OutgoingMessageHeaders

如果我们要把一个OrderResponseContext 对象插入到当前Operation Context的Outgoing Message Headers中，我们可以通过下面的代码来实现：

OrderResponseContext context = new OrderResponseContext();
MessageHeader<OrderResponseContext> header = new MessageHeader<OrderResponseContext>( context);
OperationContext.Current.OutgoingMessageHeaders.Add(header.GetUntypedHeader("name", "namespace"));

相应的，我们可以通过下面的代码从Outgoing Message Headers OrderResponseContext的数据获取的内容：

OrderResponseContext context = OperationContext.Current.IncomingMessageHeaders.GetHeader<OrderResponseContext>("name", "namespace"));

四、Sample

我们照例给出一个完整的Sample，下面是整个Solution的结构：

using System; using System.Collections.Generic; using System.Text; using System.ServiceModel; namespace Artech.ResponsiveQueuedService.ContractService Contract: Artech.ResponsiveQueuedService.Contract.IOrderRessponse

using System;
using System.Collections.Generic;
using System.Text;
using System.ServiceModel;

namespace Artech.ResponsiveQueuedService.Contract

接收来自Order processing端的Response：Order No.和Exception。

Data Contract: Artech.ResponsiveQueuedService.Contract.Order

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.Serialization;

namespace Artech.ResponsiveQueuedService.Contract

对Order的封装。

Data Contract：Artech.ResponsiveQueuedService.Contract. OrderResponseContext

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.Serialization;
using System.ServiceModel;

namespace Artech.ResponsiveQueuedService.Contract

ResponseAddress代表Host在Client Domain的Response Service的Address。同过Current把OrderResponseContext插入到Outgoing Message Headers中、以及从Ingoing Message Headers取出OrderResponseContext对象。

2．Order Processing Service：Artech.ResponsiveQueuedService.Service

using System;
using System.Collections.Generic;
using System.Text;
using Artech.ResponsiveQueuedService.Contract;
using System.ServiceModel;
using System.Net.Security;

namespace Artech.ResponsiveQueuedService.Service

在这里我们模拟了这样的场景：先通过Order Date判断Order是否过期，如果过期创建一个FaultException，否则正确处理该Order，然后通过OrderResponseContext.Current从Incoming Message Header中获取封装在OrderResponseContext对象中的Response Address，创建Binding并调用Response Service.

3. Order Processing Service Hosting: Artech.ResponsiveQueuedService.Hosting

Configuration

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <add key="msmqPath" value=".\private$\orderprocessor"/>
  </appSettings>
  <system.serviceModel>
    <bindings>
      <netMsmqBinding>
        <binding name="MsmqBinding" exactlyOnce="false" useActiveDirectory="false">
          <security>
            <transport msmqAuthenticationMode="None" msmqProtectionLevel="None" />
          </security>
        </binding>
      </netMsmqBinding>
    </bindings>
    <services>
      <service name="Artech.ResponsiveQueuedService.Service.OrderProcessorService">
        <endpoint address="net.msmq://localhost/private/orderprocessor" binding="netMsmqBinding"
            bindingConfiguration="MsmqBinding" contract="Artech.ResponsiveQueuedService.Contract.IOrderProcessor" />
      </service>
    </services>
  </system.serviceModel>
</configuration>

Program

using System;
using System.Collections.Generic;
using System.Text;
using Artech.ResponsiveQueuedService.Service;
using System.ServiceModel;
using System.Configuration;
using System.Messaging;

namespace Artech.ResponsiveQueuedService.Hosting

4. Response Service: Artech.ResponsiveQueuedService.LocalService.OrderRessponseService

using System;
using System.Collections.Generic;
using System.Text;
using Artech.ResponsiveQueuedService.Contract;
using System.ServiceModel;

namespace Artech.ResponsiveQueuedService.LocalService

5. Response Service Hosting: Artech.ResponsiveQueuedService.LocalhHosting

Configuration

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <add key="msmqPath" value=".\private$\orderresponse"/>
  </appSettings>
  <system.serviceModel>
    <bindings>
      <netMsmqBinding>
        <binding name="msmqBinding" exactlyOnce="false">
          <security>
            <transport msmqAuthenticationMode="None" msmqProtectionLevel="None" />
          </security>
        </binding>
      </netMsmqBinding>
    </bindings>
    <services>
      <service name="Artech.ResponsiveQueuedService.LocalService.OrderRessponseService">
        <endpoint address="net.msmq://localhost/private/orderresponse" binding="netMsmqBinding"
            bindingConfiguration="msmqBinding" contract="Artech.ResponsiveQueuedService.Contract.IOrderRessponse" />
      </service>
    </services>
  </system.serviceModel>
</configuration>

Program

using System;
using System.Collections.Generic;
using System.Text;
using Artech.ResponsiveQueuedService.LocalService;
using System.Configuration;
using System.ServiceModel;
using System.Messaging;

namespace Artech.ResponsiveQueuedService.LocalhHosting

6. Client: Artech.ResponsiveQueuedService.Client

Configuration:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <add key="msmqPath" value="net.msmq://localhost/private/orderresponse"/>
  </appSettings>
  <system.serviceModel>
    <bindings>
      <netMsmqBinding>
        <binding name="MsmqBinding" exactlyOnce="false" useActiveDirectory="false">
          <security>
            <transport msmqAuthenticationMode="None" msmqProtectionLevel="None" />
          </security>
        </binding>
      </netMsmqBinding>
    </bindings>
    <client>
      <endpoint address="net.msmq://localhost/private/orderprocessor" binding="netMsmqBinding"
            bindingConfiguration="MsmqBinding" contract="Artech.ResponsiveQueuedService.Contract.IOrderProcessor" name="defaultEndpoint" />
    </client>
  </system.serviceModel>
</configuration>

Program:

using System;
using System.Collections.Generic;
using System.Text;
using System.Configuration;
using System.ServiceModel;
using Artech.ResponsiveQueuedService.Contract;
using System.Messaging;

namespace Artech.ResponsiveQueuedService.Clinet

我创建了两个Order对象, 其中一个已经过期。从Configuration中取出Response Address并购建一个OrderResponseContext，然后分两次将这两个Order向Order Processing Service递交。在调用Order Processing Order的Operation Context Scope中，通过OrderResponseContext.Current将OrderResponseContext对象插入Outcoming Message Header中。

我们现在运行一下整个程序，看看最终的输出结果：

Client：

Order Processing：

Order Response：

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