How to: Create a Service That Requires Sessions

Sessions create a shared state between two or more endpoints that enables useful features such as callbacks, multi-hop security, and associations between clients and service instances. For more information about sessions in Windows Communication Foundation (WCF) applications, see Using Sessions.

To specify that a contract require its binding to support sessions

1. Create a service contract with at least one operation. For an example of how to create a service contract, see How to: Define a Windows Communication Foundation Service Contract.

2. Modify the System.ServiceModel.ServiceContractAttribute that declares the contract by setting the System.ServiceModel.ServiceContractAttribute.SessionMode property to either:

   • System.ServiceModel.SessionMode.Required if this contract must be run within a session.

   • System.ServiceModel.SessionMode.Allowed if this contract can be run within a session.

   • System.ServiceModel.SessionMode.NotAllowed if this contract must not be run within a session.

3. Configure your service endpoint to use a binding that supports sessions. The following configuration example shows the use of the System.ServiceModel.WSDualHttpBinding, which supports a WS-ReliableMessaging session.

   <appSettings>
     <!-- use appSetting to configure base address provided by host -->
     <add key="baseAddress" value="https://localhost:8080/ServiceMetadata" />
   </appSettings>
   <system.serviceModel>
     <services>
       <service 
         name="Microsoft.WCF.Documentation.DuplexHello"
         behaviorConfiguration="mex"
       >
         <endpoint
           address="/DuplexService"
           binding="wsDualHttpBinding"
           contract="Microsoft.WCF.Documentation.IDuplexHello"
          />
         <endpoint
           address=""
           binding="mexHttpBinding"
           contract="IMetadataExchange"
         />
       </service>
     </services>
     <behaviors>
       <serviceBehaviors>
         <behavior name="mex" >
           <serviceMetadata httpGetEnabled="true" />
         </behavior>
       </serviceBehaviors>
     </behaviors>
   </system.serviceModel>
   

Example

The following example code shows how to specify a contract-level session requirement and use a configuration file to support that requirement with the System.ServiceModel.WSDualHttpBinding binding.

using System;
using System.Collections.Generic;
using System.ServiceModel;
using System.Threading;

namespace Microsoft.WCF.Documentation
{
  [ServiceContract(
    Name = "SampleDuplexHello",
    Namespace = "http://microsoft.wcf.documentation",
    CallbackContract = typeof(IHelloCallbackContract),
    SessionMode = SessionMode.Required
  )]
  public interface IDuplexHello
  {
    [OperationContract(IsOneWay = true)]
    void Hello(string greeting);
  }

  public interface IHelloCallbackContract
  {
    [OperationContract(IsOneWay = true)]
    void Reply(string responseToGreeting);
  }

  [ServiceBehaviorAttribute(InstanceContextMode=InstanceContextMode.PerSession)]
  public class DuplexHello : IDuplexHello
  {

    public DuplexHello()
    {
      Console.WriteLine("Service object created: " + this.GetHashCode().ToString());
    }

    ~DuplexHello()
    {
      Console.WriteLine("Service object destroyed: " + this.GetHashCode().ToString());
    }

    public void Hello(string greeting)
    {
      Console.WriteLine("Caller sent: " + greeting);
      Console.WriteLine("Session ID: " + OperationContext.Current.SessionId);
      Console.WriteLine("Waiting two seconds before returning call.");
      // Put a slight delay to demonstrate asynchronous behavior on client.
      Thread.Sleep(2000);
      IHelloCallbackContract callerProxy
        = OperationContext.Current.GetCallbackChannel<IHelloCallbackContract>();
      string response = "Service object " + this.GetHashCode().ToString() + " received: " + greeting;
      Console.WriteLine("Sending back: " + response);
      callerProxy.Reply(response);
    }
  }
}

<appSettings>
  <!-- use appSetting to configure base address provided by host -->
  <add key="baseAddress" value="https://localhost:8080/ServiceMetadata" />
</appSettings>
<system.serviceModel>
  <services>
    <service 
      name="Microsoft.WCF.Documentation.DuplexHello"
      behaviorConfiguration="mex"
    >
      <endpoint
        address="/DuplexService"
        binding="wsDualHttpBinding"
        contract="Microsoft.WCF.Documentation.IDuplexHello"
       />
      <endpoint
        address=""
        binding="mexHttpBinding"
        contract="IMetadataExchange"
      />
    </service>
  </services>
  <behaviors>
    <serviceBehaviors>
      <behavior name="mex" >
        <serviceMetadata httpGetEnabled="true" />
      </behavior>
    </serviceBehaviors>
  </behaviors>
</system.serviceModel>

See Also

Reference

System.ServiceModel.ServiceContractAttribute
System.ServiceModel.ServiceContractAttribute.SessionMode
System.ServiceModel.SessionMode

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Build Date: 2009-08-07