OperationContextScope

项目
09/04/2008

OperationContextScope 示例演示如何使用头在 Windows Communication Foundation (WCF) 调用中发送额外的信息。在此示例中，服务器和客户端都是控制台应用程序。

提示

本主题的末尾介绍了此示例的设置过程和生成说明。

此示例演示客户端如何使用 OperationContextScope 以 MessageHeader 的方式发送额外的信息。OperationContextScope 对象是通过将其范围设置为通道来创建的。必须转换为远程服务的头可以添加到 OutgoingMessageHeaders 集合中。可以通过访问 IncomingMessageHeaders 在服务上检索添加到此集合中的头。它的调用是在多个通道进行的，添加到客户端的头然后将只应用于用来创建 OperationContextScope 的通道。

MessageHeaderReader

这是从客户端接收消息，并尝试在 IncomingMessageHeaders 集合中查找头的示例服务。客户端传递在头中发送的 GUID，服务则检索自定义头，如果存在自定义头，则将其与客户端作为参数传递的 GUID 进行比较。

public bool RetrieveHeader(string guid)
{
     MessageHeaders messageHeaderCollection = 
             OperationContext.Current.IncomingMessageHeaders;
     String guidHeader = null;

     Console.WriteLine("Trying to check if IncomingMessageHeader " +
               " collection contains header with value {0}", guid);
     if (messageHeaderCollection.FindHeader(
                       CustomHeader.HeaderName, 
                       CustomHeader.HeaderNamespace) != -1)
     {
          guidHeader = messageHeaderCollection.GetHeader<String>(
           CustomHeader.HeaderName, CustomHeader.HeaderNamespace);
     }
     else
     {
          Console.WriteLine("No header was found");
     }
     if (guidHeader != null)
     {
          Console.WriteLine("Found header with value {0}. "+ 
         "Does it match with GUID sent as parameter: {1}", 
          guidHeader, guidHeader.Equals(guid));
      }

      Console.WriteLine();
      //Return true if header is present and equals the guid sent by
      // client as argument
      return (guidHeader != null && guidHeader.Equals(guid));
}

MessageHeaderClient

这是使用通过 ServiceModel Metadata Utility Tool (Svcutil.exe) 生成的代理与远程服务通信的客户端实现。它首先创建 MessageHeaderReaderClient 的两个代理对象。

//Create two clients to the remote service.
MessageHeaderReaderClient client1 = new MessageHeaderReaderClient();
MessageHeaderReaderClient client2 = new MessageHeaderReaderClient();

客户端然后创建 OperationContextScope 并将其范围设置为 client1。它将 MessageHeader 添加到 OutgoingMessageHeaders 中，并在两个客户端上都进行一次调用。它通过检查从 RetrieveHeader 调用返回的值，确保只在 client1 上发送头，不在 client2 上发送头。

using (new OperationContextScope(client1.InnerChannel))
{
    //Create a new GUID that is sent as the header.
    String guid = Guid.NewGuid().ToString();

    //Create a MessageHeader for the GUID we just created.
    MessageHeader customHeader = MessageHeader.CreateHeader(CustomHeader.HeaderName, CustomHeader.HeaderNamespace, guid);

    //Add the header to the OutgoingMessageHeader collection.
    OperationContext.Current.OutgoingMessageHeaders.Add(customHeader);

    //Now call RetreieveHeader on both the proxies. Since the OperationContextScope is tied to 
    //client1's InnerChannel, the header should only be added to calls made on that client.
    //Calls made on client2 should not be sending the header across even though the call
    //is made in the same OperationContextScope.
    Console.WriteLine("Using client1 to send message");
    Console.WriteLine("Did server retrieve the header? : Actual: {0}, Expected: True", client1.RetrieveHeader(guid));

    Console.WriteLine();
    Console.WriteLine("Using client2 to send message");
    Console.WriteLine("Did server retrieve the header? : Actual: {0}, Expected: False", client2.RetrieveHeader(guid));
}

此示例是自承载的。下面提供了运行示例的示例输出：

Prompt> Service.exe
The service is ready.
Press <ENTER> to terminate service.

Trying to check if IncomingMessageHeader collection contains header with value 2239da67-546f-42d4-89dc-8eb3c06215d8
Found header with value 2239da67-546f-42d4-89dc-8eb3c06215d8. Does it match with GUID sent as parameter: True

Trying to check if IncomingMessageHeader collection contains header with value 2239da67-546f-42d4-89dc-8eb3c06215d8
No header was found


Prompt>Client.exe
Using client1 to send message
Did server retrieve the header? : Actual: True, Expected: True

Using client2 to send message
Did server retrieve the header? : Actual: False, Expected: False

Press <ENTER> to terminate client.

设置、生成和运行示例

请确保已经执行了 Windows Communication Foundation 示例的一次性安装过程。
若要生成 C# 或 Visual Basic .NET 版本的解决方案，请按照生成 Windows Communication Foundation 示例中的说明进行操作。
若要用单机配置或跨计算机配置来运行示例，请按照运行 Windows Communication Foundation 示例中的说明进行操作。

通过

OperationContextScope

MessageHeaderReader

MessageHeaderClient

设置、生成和运行示例

其他资源