跟着Artech学习WCF扩展(4) 扩展MessageInspector

自定义MessageInspector

在client端和service端都有自己的MessageInspector，client端叫做ClientMessageInspector，实现System.ServiceModel.Dispatcher.IClientMessageInspector interface，而service端叫做 DispatchMessageInspector，实现了System.ServiceModel.Dispatcher.IDispatchMessageInspector interface。DispatchMessageInspector允许你在request message交付到具体的DispatchOperation付诸执行之前或者reply message返回client之前对incoming message/outgoing message进行检验、修改或者其他一些基于message的操作；

IDispatchMessageInspector的定义很简单

public interface IDispatchMessageInspector
{
    // Methods
    object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext);
    void BeforeSendReply(ref Message reply, object correlationState);
}

在实际的项目开发中，MessageInspector使用相当广范，比如：我们可以定义自己的MessageInspector实现Logging功能；或者在Client端通过ClientMessageInspector添加一些与业务无关的context信息，并在service通过DispatchMessageInspector将其取出。在本系列后续的部分我将给你一个application context propagation的具体应用。

剩下的地方在这里：点我

代码下载：点我

在Client端对 IClientMessageInspector 进行实现

在service端对IDispatchMessageInspector进行实现

但Artech在service端对 ICallContextInitializer进行了实现

出去学习的目的，拼拼代码也把IDispatchMessageInspector实现了

不过不知道对不对自己拼代码实在是盲人摸像搞了一天才弄明白，不对是还没弄明白

通过细查发现这个扩展实在是太有用了外星人

部分代码如下作为备份

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;
using System.ServiceModel.Channels;
 
namespace Artech.ContextPropagation
{
   public class DispatchMessageInspectorTest:System.ServiceModel.Dispatcher.IDispatchMessageInspector
    {
       public bool IsBidirectional
       { get; set; }
 
       public DispatchMessageInspectorTest()
           : this(false)
       {
 
       }
 
       public DispatchMessageInspectorTest(bool isBidirectional)
       {
           this.IsBidirectional = isBidirectional;
       }
 
 
  
 
 
        //DispatchMessageInspector
        public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
        {
            ApplicationContext context = request.Headers.GetHeader<ApplicationContext>(ApplicationContext.ContextHeaderLocalName, ApplicationContext.ContextHeaderNamespace);
            if (context == null)
            {
                return null;
            }
 
            ApplicationContext.Current = context;
            return ApplicationContext.Current;
        }
 
        public void BeforeSendReply(ref Message reply, object correlationState)
        {
 
            if (!this.IsBidirectional)
            {
                return;
            }
 
            ApplicationContext context = correlationState as ApplicationContext;
            if (context == null)
            {
                return;
            }
            MessageHeader<ApplicationContext> contextHeader = new MessageHeader<ApplicationContext>(context);
            OperationContext.Current.OutgoingMessageHeaders.Add(contextHeader.GetUntypedHeader(ApplicationContext.ContextHeaderLocalName, ApplicationContext.ContextHeaderNamespace));
            ApplicationContext.Current = null;
 
        }
 
 
 
 
    }
}

=========

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;
using System.ServiceModel.Description;
 
namespace Artech.ContextPropagation
{
    public class DispatchMessageInspectorTestBehavior : IEndpointBehavior
    {
        public bool IsBidirectional
        { get; set; }
 
 
        public DispatchMessageInspectorTestBehavior()
            : this(false)
        {
 
        }
 
        public DispatchMessageInspectorTestBehavior(bool isBidirectional)
        {
            this.IsBidirectional = isBidirectional;
        }
 
 
        public void AddBindingParameters(ServiceEndpoint endpoint, System.ServiceModel.Channels.BindingParameterCollection bindingParameters)
        {
           
        }
 
        public void ApplyClientBehavior(ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.ClientRuntime clientRuntime)
        {
            clientRuntime.MessageInspectors.Add(new ContextAttachingMessageInspector(this.IsBidirectional));
        
        }
 
        public void ApplyDispatchBehavior(ServiceEndpoint endpoint, System.ServiceModel.Dispatcher.EndpointDispatcher endpointDispatcher)
        {
 
            DispatchMessageInspectorTest inspector = new DispatchMessageInspectorTest(this.IsBidirectional);
            endpointDispatcher.DispatchRuntime.MessageInspectors.Add(inspector);
        }
 
        public void Validate(ServiceEndpoint endpoint)
        {
             
        }
    }
}

==============

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel.Configuration;
using System.Configuration;
 
namespace Artech.ContextPropagation
{
   public class DispatchMessageInspectorTestElement:BehaviorExtensionElement
    {
       [ConfigurationProperty("isBidirectional", DefaultValue = false)]
       public bool IsBidirectional
       {
           get
           {
               return (bool)this["isBidirectional"];
           }
           set
           {
               this["isBidirectional"] = value;
           }
       }
 
        public override Type BehaviorType
        {
            get { return typeof(DispatchMessageInspectorTestBehavior); }
        }
 
        protected override object CreateBehavior()
        {
            return new DispatchMessageInspectorTestBehavior(IsBidirectional);
        }
    }
}