CallContext Class

Definition

Namespace:

System.Runtime.Remoting.Messaging

Assembly:

mscorlib.dll

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

public ref class CallContext sealed

[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
[System.Security.SecurityCritical]
public sealed class CallContext

[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
[<System.Security.SecurityCritical>]
type CallContext = class

Public NotInheritable Class CallContext

Inheritance

Object

CallContext

Attributes

SerializableAttribute ComVisibleAttribute SecurityCriticalAttribute

Examples

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.dll>
#using <system.runtime.remoting.dll>
#using <service.dll>

using namespace System;
using namespace System::Runtime::Remoting;
using namespace System::Runtime::Remoting::Channels;
using namespace System::Runtime::Remoting::Channels::Tcp;
using namespace System::Runtime::Remoting::Messaging;
using namespace System::Security::Principal;
int main()
{
   GenericIdentity^ ident = gcnew GenericIdentity( "Bob" );
   array<String^>^id = gcnew array<String^>(1);
   id[ 0 ] = "Level1";
   GenericPrincipal^ prpal = gcnew GenericPrincipal( ident,id );
   LogicalCallContextData ^ data = gcnew LogicalCallContextData( prpal );

   //Enter data into the CallContext
   CallContext::SetData( "test data", data );
   Console::WriteLine( data->numOfAccesses );
   ChannelServices::RegisterChannel( gcnew TcpChannel );
   RemotingConfiguration::RegisterActivatedClientType( HelloServiceClass::typeid, "tcp://localhost:8082" );
   HelloServiceClass ^ service = gcnew HelloServiceClass;
   if ( service == nullptr )
   {
      Console::WriteLine( "Could not locate server." );
      return 0;
   }

   // 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 = static_cast<LogicalCallContextData ^>(CallContext::GetData( "test data" ));
   Console::WriteLine( data->numOfAccesses );
   Console::WriteLine( returnedData->numOfAccesses );
   return 0;
}

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 {
   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);
   }
}

Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Channels
Imports System.Runtime.Remoting.Channels.Tcp
Imports System.Runtime.Remoting.Messaging
Imports System.Security.Principal
Imports System.Security.Permissions


Public Class ClientClass
   <PermissionSet(SecurityAction.LinkDemand)> _
   Public Shared Sub Main()
      
      Dim ident As New GenericIdentity("Bob")
      Dim prpal As New GenericPrincipal(ident, New String() {"Level1"})
      Dim data As New LogicalCallContextData(prpal)
      
      'Enter data into the CallContext
      CallContext.SetData("test data", data)
      
      
      Console.WriteLine(data.numOfAccesses)
      
      ChannelServices.RegisterChannel(New TcpChannel())
      
      RemotingConfiguration.RegisterActivatedClientType(GetType(HelloServiceClass), "tcp://localhost:8082")
      
      Dim service As New HelloServiceClass()
      
      If service Is Nothing Then
         Console.WriteLine("Could not locate server.")
         Return
      End If
      
      
      ' 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
      Dim returnedData As LogicalCallContextData = CType(CallContext.GetData("test data"), LogicalCallContextData)
      
      Console.WriteLine(data.numOfAccesses)
      Console.WriteLine(returnedData.numOfAccesses)

   End Sub

End Class

Remarks

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.

Note

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

Note

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.

Properties

HostContext

Gets or sets the host context associated with the current thread.

Methods

Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
FreeNamedDataSlot(String)	Empties a data slot with the specified name.
GetData(String)	Retrieves an object with the specified name from the CallContext.
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetHeaders()	Returns the headers that are sent along with the method call.
GetType()	Gets the Type of the current instance. (Inherited from Object)
LogicalGetData(String)	Retrieves an object with the specified name from the logical call context.
LogicalSetData(String, Object)	Stores a given object in the logical call context and associates it with the specified name.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
SetData(String, Object)	Stores a given object and associates it with the specified name.
SetHeaders(Header[])	Sets the headers that are sent along with the method call.
ToString()	Returns a string that represents the current object. (Inherited from Object)

See also

• Header