CallContext Class
Provides a set of properties that are carried with the execution code path. This class cannot be inherited.
Assembly: mscorlib (in mscorlib.dll)
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.
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All methods in CallContext are static and operate on the call context in the current Thread. |
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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.
Imports System 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 'Main End Class 'ClientClass
#using <mscorlib.dll>
#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 = new GenericIdentity(S"Bob");
String* id __gc[] = new String* __gc[1];
id[0] = S"Level1";
GenericPrincipal* prpal = new GenericPrincipal(ident, id );
LogicalCallContextData* data = new LogicalCallContextData(prpal);
//Enter data into the CallContext
CallContext::SetData(S"test data", data);
Console::WriteLine(data->numOfAccesses);
ChannelServices::RegisterChannel(new TcpChannel());
RemotingConfiguration::RegisterActivatedClientType(__typeof(HelloServiceClass),
S"tcp://localhost:8082");
HelloServiceClass* service = new HelloServiceClass();
if (service == 0)
{
Console::WriteLine(S"Could not locate server.");
return 0;
}
// call remote method
Console::WriteLine();
Console::WriteLine(S"Calling remote Object*");
Console::WriteLine(service->HelloMethod(S"Caveman"));
Console::WriteLine(service->HelloMethod(S"Spaceman"));
Console::WriteLine(service->HelloMethod(S"Bob"));
Console::WriteLine(S"Finished remote Object* call");
Console::WriteLine();
//Extract the returned data from the call context
LogicalCallContextData* returnedData =
static_cast<LogicalCallContextData*>(CallContext::GetData(S"test data"));
Console::WriteLine(data->numOfAccesses);
Console::WriteLine(returnedData->numOfAccesses);
return 0;
}
- SecurityPermission
For operating with infrastructure code. Demand value: SecurityAction.LinkDemand; Permission Value: SecurityPermissionFlag.Infrastructure
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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