wcf之OperationContextScope

作用：使用消息头向服务发送额外的信息。

1.客户端代码如下：

 namespace Client
 {
     class Program
     {
         static void Main(string[] args)
         {
             CalculatorClient client = new CalculatorClient("secure");
             double n1 = 5.6;
             double n2 = 7.3;
             double result;

             result = client.Add(n2, n1);
             Console.WriteLine("执行加法后的结果为：{0}", result.ToString());

             result = client.Subtract(n2, n1);
             Console.WriteLine("执行减法后的结果为：{0}", result.ToString());

             result = client.Multiply(n1, n2);
             Console.WriteLine("执行乘法后的结果为：{0}", result.ToString());

             result = client.Divide(n1, n2);
             Console.WriteLine("执行除法后的结果为：{0}", result.ToString());

             //CalculatorSessionClient clientSeesion = new CalculatorSessionClient();
             //string s = clientSeesion.test("你好我做一个测试！");
             //string b = clientSeesion.GetServiceDescriptionInfo();
             //Console.WriteLine(s);
             //Console.WriteLine(b); 

             Test();

         }

         static void Test()
         {
             CalculatorSessionClient wcfClient = new CalculatorSessionClient();
             try
             {
                 using (OperationContextScope scope = new OperationContextScope(wcfClient.InnerChannel))
                 {
                     MessageHeader header
                       = MessageHeader.CreateHeader(
                       "Service-Bound-CustomHeader",
                       "http://Microsoft.WCF.Documentation",
                       "Custom Happy Value."
                       );
                     OperationContext.Current.OutgoingMessageHeaders.Add(header);

                     // Making calls.
                     Console.WriteLine("Enter the greeting to send: ");
                     string greeting = Console.ReadLine();

                     //Console.ReadLine();
                     header = MessageHeader.CreateHeader(
                         "Service-Bound-OneWayHeader",
                         "http://Microsoft.WCF.Documentation",
                         "Different Happy Value."
                       );
                     OperationContext.Current.OutgoingMessageHeaders.Add(header);//TODO:自定义传出消息头的用处？

                     // One-way
                     wcfClient.test(greeting);

                     // Done with service.
                     wcfClient.Close();
                     Console.WriteLine("Done!");
                     Console.ReadLine();
                 }
             }
             catch (TimeoutException timeProblem)
             {
                 Console.WriteLine("The service operation timed out. " + timeProblem.Message);
                 Console.ReadLine();
                 wcfClient.Abort();
             }
             catch (CommunicationException commProblem)
             {
                 Console.WriteLine("There was a communication problem. " + commProblem.Message);
                 Console.ReadLine();
                 wcfClient.Abort();
             }

         }
     }
 }

2.服务端代码：

 namespace Microsoft.ServiceModel.Samples
 {
     class Program
     {
         static void Main(string[] args)
         {
             //创建一个ServiceHost
             using (ServiceHost serviceHost = new ServiceHost(typeof(CalculatorService)))
             {
                 // Open the ServiceHost to create listeners
                 serviceHost.Open();
                 Console.WriteLine("服务已经开启！");
                 Console.WriteLine("按回车键结束服务！");
                 Console.WriteLine();
                 Console.ReadLine();

                 serviceHost.Close();

             }
         }

     }
     [ServiceContract]//定义服务协定完成
     public interface ICalculator
     {
         [OperationContract]
         double Add(double n1, double n2);
         [OperationContract]
         double Subtract(double n1, double n2);
         [OperationContract]
         double Multiply(double n1, double n2);
         [OperationContract]
         double Divide(double n1, double n2);
     }

     [ServiceContract]
     public interface ICalculatorSession
     {
         [OperationContract]
         string test(string s);

         [OperationContract]
         string GetServiceDescriptionInfo();
     }

     public class CalculatorService : ICalculator, ICalculatorSession
     {
         public double Add(double n1, double n2)
         {
             return n1 + n2;
         }

         public double Subtract(double n1, double n2)
         {
             return n1 - n2;
         }

         public double Multiply(double n1, double n2)
         {
             return n1 * n2;
         }

         public double Divide(double n1, double n2)
         {
             return n1 / n2;
         }

         public string test(string s)
         {
             Console.WriteLine("Service Said" + s);
             WriteHeaders(OperationContext.Current.IncomingMessageHeaders);
             return s;
         }

         public string GetServiceDescriptionInfo()
         {
             StringBuilder sb = new StringBuilder();
             OperationContext operationContext = OperationContext.Current;
             ServiceHost serviceHost = (ServiceHost)operationContext.Host;
             ServiceDescription dec = serviceHost.Description;
             sb.Append("Base addresses:\n");
             foreach (Uri url in serviceHost.BaseAddresses)
             {
                 sb.Append(" " + url + "\n");
             }
             sb.Append("Service endpoint:\n");
             foreach (ServiceEndpoint endPoint in dec.Endpoints)
             {
                 sb.Append("Address:" + endPoint.Address + "\n");
                 sb.Append("Binding:" + endPoint.Binding + "\n");
                 sb.Append("Contract:" + endPoint.Contract + "\n");
             }

             return sb.ToString();
         }

         private void WriteHeaders(MessageHeaders headers)
         {
             foreach (MessageHeaderInfo header in headers)
             {
                     Console.WriteLine("\t" + header.Actor);
                     Console.ForegroundColor = ConsoleColor.White;
                     Console.WriteLine("\t" + header.Name);
                     Console.ForegroundColor = ConsoleColor.Yellow;
                     Console.WriteLine("\t" + header.Namespace);
                     Console.WriteLine("\t" + header.Relay);
                     if (header.IsReferenceParameter == true)
                      {
                          Console.WriteLine("IsReferenceParameter header detected: " + header.ToString());
                      }
             }
             Console.ResetColor();
         }
     }

 }

这个实例演示的是客户端通过OutgoingMessageHeaders添加了一些信息，然后服务端通过IncomingMessageHeaders

附：(也许你会有疑问，事情都是OperationContext做的，要OperationContextScope 干什么：个人理解OperationContextScope 类似于数据库连接对象类，wcfClient.InnerChannel就好像是连接字符串，告诉要连接到哪去，整个OperationContextScope 块就像是数据库中的当期连接，信息头就好像是sql语句，出了OperationContextScope 块范围就好数据库断开了连接，进行其他操作要重新连接，OperationContext 就好像是Command对象执行一些操作)

OperationContextScope 对象建立了当前操作上下文之后，可以使用 OperationContext 执行以下操作：

• 访问和修改传入和传出消息头和其他属性。

• 访问运行库，包括调度程序、主机、信道和扩展。

• 访问其他类型的上下文，如安全、实例和请求上下文。

• 访问与 OperationContext 对象关联的信道，或（如果信道实现System.ServiceModel.Channels.ISession）访问关联信道的会话标识符。

创建了 OperationContextScope 后，将存储当前的 OperationContext，并且新的 OperationContext 由Current 属性所返回。释放 OperationContextScope 后，将还原原始 OperationContext。