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CallContext Class

Provides a set of properties that are carried with the execution code path. This class cannot be inherited.

Namespace: System.Runtime.Remoting.Messaging
Assembly: mscorlib (in mscorlib.dll)

[SerializableAttribute] 
[ComVisibleAttribute(true)] 
public sealed class CallContext
/** @attribute SerializableAttribute() */ 
/** @attribute ComVisibleAttribute(true) */ 
public final class CallContext
SerializableAttribute 
ComVisibleAttribute(true) 
public final class CallContext

CallContext is a specialized collection object similar to a Thread Local Storage for method calls and provides data slots that are unique to each logical thread of execution. The slots are not shared across call contexts on other logical threads. Objects can be added to the CallContext as it travels down and back up the execution code path, and examined by various objects along the path.

When a remote method call is made to an object in another AppDomain, the CallContext class generates a LogicalCallContext instance that travels along with the remote call. Only objects that expose the ILogicalThreadAffinative interface and are stored in the CallContext are propagated outside the AppDomain in a LogicalCallContext. Objects that do not support this interface are not transmitted in LogicalCallContext instances with remote method calls.

NoteNote

All methods in CallContext are static and operate on the call context in the current Thread.

NoteNote

This class makes a link demand. A SecurityException is thrown if the immediate caller does not have infrastructure permission. See Link Demands for more information.

The following code example demonstrates the use of the CallContext class to transmit Principal and Identity Objects to a remote location for identification. To view the code for the LogicalCallContextData class used in this sample, see the example for the ILogicalThreadAffinative interface. To view the code for the HelloServiceClass class used in this sample, see the example for the GetData method. To view the code for the server class used in this sample, see the example for the RegisterActivatedServiceType class.

using System;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Channels;
using System.Runtime.Remoting.Channels.Tcp;
using System.Runtime.Remoting.Messaging;
using System.Security.Principal;
using System.Security.Permissions;

public class ClientClass {
   [PermissionSet(SecurityAction.LinkDemand)]
   public static void Main() {
      
      GenericIdentity ident = new GenericIdentity("Bob");
      GenericPrincipal prpal = new GenericPrincipal(ident, 
                                                    new string[] {"Level1"});
      LogicalCallContextData data = new LogicalCallContextData(prpal);      
      
      //Enter data into the CallContext
      CallContext.SetData("test data", data);

      
      Console.WriteLine(data.numOfAccesses);

      ChannelServices.RegisterChannel(new TcpChannel());

      RemotingConfiguration.RegisterActivatedClientType(typeof(HelloServiceClass),
                                                        "tcp://localhost:8082");

      HelloServiceClass service = new HelloServiceClass();

      if(service == null) {
          Console.WriteLine("Could not locate server.");
          return;
      }


      // call remote method
      Console.WriteLine();
      Console.WriteLine("Calling remote object");
      Console.WriteLine(service.HelloMethod("Caveman"));
      Console.WriteLine(service.HelloMethod("Spaceman"));
      Console.WriteLine(service.HelloMethod("Bob"));
      Console.WriteLine("Finished remote object call");
      Console.WriteLine();

      //Extract the returned data from the call context
      LogicalCallContextData returnedData = 
         (LogicalCallContextData)CallContext.GetData("test data");

      Console.WriteLine(data.numOfAccesses);
      Console.WriteLine(returnedData.numOfAccesses);
   }
}

System.Object
  System.Runtime.Remoting.Messaging.CallContext
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0
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