IMessageSink IMessageSink IMessageSink IMessageSink Interface


Defines the interface for a message sink.

public interface class IMessageSink
public interface IMessageSink
type IMessageSink = interface
Public Interface IMessageSink


The following code example shows the implementation of the IMessageSink interface. Note that the sample assumes type definitions and assembly references that must be provided for the sample to compile.

#using <System.Runtime.Remoting.dll>
#using <System.dll>
#using <IMessageSink_Share.dll>

using namespace System;
using namespace System::Collections;
using namespace System::Threading;
using namespace System::Runtime::Remoting;
using namespace System::Runtime::Remoting::Channels;
using namespace System::Runtime::Remoting::Channels::Http;
using namespace System::Runtime::Remoting::Proxies;
using namespace System::Runtime::Remoting::Messaging;
using namespace System::Security::Permissions;
using namespace Share;

public ref class MyProxy: public RealProxy
   String^ myUrl;
   String^ myObjectURI;
   IMessageSink^ myMessageSink;


   MyProxy( Type^ myType, String^ myUrl1 )
      : RealProxy( myType )
      myUrl = myUrl1;
      array<IChannel^>^myRegisteredChannels = ChannelServices::RegisteredChannels;
      IEnumerator^ myEnum = myRegisteredChannels->GetEnumerator();
      while ( myEnum->MoveNext() )
         IChannel^ channel = safe_cast<IChannel^>(myEnum->Current);
         if ( dynamic_cast<IChannelSender^>(channel) )
            IChannelSender^ myChannelSender = dynamic_cast<IChannelSender^>(channel);
            myMessageSink = myChannelSender->CreateMessageSink( myUrl, nullptr, myObjectURI );
            if ( myMessageSink != nullptr )

      if ( myMessageSink == nullptr )
         throw gcnew Exception( String::Format( "A supported channel could not be found for myUrl1:{0}", myUrl ) );

   virtual IMessage^ Invoke( IMessage^ myMesg ) override
      Console::WriteLine( "MyProxy.Invoke Start" );
      if ( dynamic_cast<IMethodCallMessage^>(myMesg) )
            Console::WriteLine( "IMethodCallMessage" );

      if ( dynamic_cast<IMethodReturnMessage^>(myMesg) )
            Console::WriteLine( "IMethodReturnMessage" );

      Console::WriteLine( "Message Properties" );
      IDictionary^ myDictionary = myMesg->Properties;
      IDictionaryEnumerator^ myEnum = dynamic_cast<IDictionaryEnumerator^>(myDictionary->GetEnumerator());
      while ( myEnum->MoveNext() )
         Object^ myKey = myEnum->Key;
         String^ myKeyName = myKey->ToString();
         Object^ myValue = myEnum->Value;
         Console::WriteLine( "{0} : {1}", myKeyName, myEnum->Value );
         if ( myKeyName->Equals( "__Args" ) )
            array<Object^>^myArgs = (array<Object^>^)myValue;
            for ( int myInt = 0; myInt < myArgs->Length; myInt++ )
               Console::WriteLine( "arg: {0} myValue: {1}", myInt, myArgs[ myInt ] );

         if ( (myKeyName->Equals( "__MethodSignature" )) && (nullptr != myValue) )
            array<Object^>^myArgs = (array<Object^>^)myValue;
            for ( int myInt = 0; myInt < myArgs->Length; myInt++ )
               Console::WriteLine( "arg: {0} myValue: {1}", myInt, myArgs[ myInt ] );

      Console::WriteLine( "myUrl1 {0} object URI{1}", myUrl, myObjectURI );
      myDictionary->default[ "__Uri" ] = myUrl;
      Console::WriteLine( "URI {0}", myDictionary->default[ "__URI" ] );
      IMessage^ myRetMsg = myMessageSink->SyncProcessMessage( myMesg );
      if ( dynamic_cast<IMethodReturnMessage^>(myRetMsg) )
         IMethodReturnMessage^ myMethodReturnMessage = dynamic_cast<IMethodReturnMessage^>(myRetMsg);

      Console::WriteLine( "MyProxy.Invoke - Finish" );
      return myRetMsg;


// Main function that drives the whole sample
int main()
   ChannelServices::RegisterChannel( gcnew HttpChannel, false );
   Console::WriteLine( "Remoting Sample:" );
   Console::WriteLine( "Generate a new MyProxy using the Type" );
   Type^ myType = MyHelloService::typeid;
   String^ myUrl1 = "http://localhost/myServiceAccess.soap";
   MyProxy^ myProxy = gcnew MyProxy( myType,myUrl1 );
   Console::WriteLine( "Obtain the transparent proxy from myProxy" );
   MyHelloService^ myService = dynamic_cast<MyHelloService^>(myProxy->GetTransparentProxy());
   Console::WriteLine( "Calling the Proxy" );
   String^ myReturnString = myService->myFunction( "bill" );
   Console::WriteLine( "Checking result : {0}", myReturnString );
   if ( myReturnString->Equals( "Hi there bill, you are using .NET Remoting" ) )
      Console::WriteLine( "myService.HelloMethod PASSED : returned {0}", myReturnString );
      Console::WriteLine( "myService.HelloMethod FAILED : returned {0}", myReturnString );

using System;
using System.Collections;
using System.Threading;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Channels;
using System.Runtime.Remoting.Channels.Http;
using System.Runtime.Remoting.Proxies;
using System.Runtime.Remoting.Messaging;
using System.Security.Permissions;
using Share;	

namespace MyNameSpace
   public class MyProxy : RealProxy
      string myUrl;
      string myObjectURI;
      IMessageSink myMessageSink;

      public MyProxy(Type myType, string myUrl1)
         : base(myType)
         myUrl = myUrl1;

         IChannel[] myRegisteredChannels = ChannelServices.RegisteredChannels;
         foreach (IChannel channel in myRegisteredChannels )
            if (channel is IChannelSender)
               IChannelSender myChannelSender = (IChannelSender)channel;

               myMessageSink = myChannelSender.CreateMessageSink(myUrl, null, out myObjectURI);
               if (myMessageSink != null)

         if (myMessageSink == null)
            throw new Exception("A supported channel could not be found for myUrl1:"+ myUrl);

      [SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.Infrastructure)]
      public override IMessage Invoke(IMessage myMesg)
         Console.WriteLine("MyProxy.Invoke Start");

         if (myMesg is IMethodCallMessage)

         if (myMesg is IMethodReturnMessage)

         Console.WriteLine("Message Properties");
         IDictionary myDictionary = myMesg.Properties;
         IDictionaryEnumerator myEnum = (IDictionaryEnumerator) myDictionary.GetEnumerator();

         while (myEnum.MoveNext())
            object myKey = myEnum.Key;
            string myKeyName = myKey.ToString();
            object myValue = myEnum.Value;

            Console.WriteLine("{0} : {1}", myKeyName, myEnum.Value);
            if (myKeyName == "__Args")
               object[] myArgs = (object[])myValue;
               for (int myInt = 0; myInt < myArgs.Length; myInt++)
                  Console.WriteLine("arg: {0} myValue: {1}", myInt, myArgs[myInt]);

            if ((myKeyName == "__MethodSignature") && (null != myValue))
               object[] myArgs = (object[])myValue;
               for (int myInt = 0; myInt < myArgs.Length; myInt++)
                  Console.WriteLine("arg: {0} myValue: {1}", myInt, myArgs[myInt]);

         Console.WriteLine("myUrl1 {0} object URI{1}",myUrl,myObjectURI);

         myDictionary["__Uri"] = myUrl;
         Console.WriteLine("URI {0}", myDictionary["__URI"]);
         IMessage myRetMsg = myMessageSink.SyncProcessMessage(myMesg);

         if (myRetMsg is IMethodReturnMessage)
            IMethodReturnMessage myMethodReturnMessage = (IMethodReturnMessage)myRetMsg;

         Console.WriteLine("MyProxy.Invoke - Finish");
         return myRetMsg;

   // Main class that drives the whole sample
   public class ProxySample
      public static void Main()
         ChannelServices.RegisterChannel(new HttpChannel());

         Console.WriteLine("Remoting Sample:");

         Console.WriteLine("Generate a new MyProxy using the Type");
         Type myType = typeof(MyHelloService);
         string myUrl1 = "http://localhost/myServiceAccess.soap";
         MyProxy myProxy = new MyProxy(myType, myUrl1);

         Console.WriteLine("Obtain the transparent proxy from myProxy");
         MyHelloService myService = (MyHelloService)myProxy.GetTransparentProxy();

         Console.WriteLine("Calling the Proxy");
         string myReturnString = myService.myFunction("bill");

         Console.WriteLine("Checking result : {0}", myReturnString);

         if (myReturnString == "Hi there bill, you are using .NET Remoting")
            Console.WriteLine("myService.HelloMethod PASSED : returned {0}", myReturnString);
            Console.WriteLine("myService.HelloMethod FAILED : returned {0}", myReturnString);

Imports System
Imports System.Collections
Imports System.Threading
Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Channels
Imports System.Runtime.Remoting.Channels.Http
Imports System.Runtime.Remoting.Proxies
Imports System.Runtime.Remoting.Messaging
Imports System.Security.Permissions
Imports Share

Namespace MyNameSpace

   Public Class MyProxy
      Inherits RealProxy
      Private myUrl As String
      Private myObjectURI As String
      Private myMessageSink As IMessageSink

      <PermissionSet(SecurityAction.LinkDemand)> _
      Public Sub New(myType As Type, myUrl1 As String)

         myUrl = myUrl1

         Dim myRegisteredChannels As IChannel() = ChannelServices.RegisteredChannels

         Dim channel As IChannel
         For Each channel In  myRegisteredChannels
            If TypeOf channel Is IChannelSender Then
               Dim myChannelSender As IChannelSender = CType(channel, IChannelSender)

               myMessageSink = myChannelSender.CreateMessageSink(myUrl, Nothing, myObjectURI)
               If Not (myMessageSink Is Nothing) Then
                  Exit For
               End If
            End If
         Next channel
         If myMessageSink Is Nothing Then
            Throw New Exception("A supported channel could not be found for myUrl1:" + myUrl)
         End If
      End Sub 'New

      <SecurityPermission(SecurityAction.LinkDemand, Flags := SecurityPermissionFlag.Infrastructure)> _
      Public Overrides Function Invoke(ByVal myMesg As IMessage) As IMessage
         Console.WriteLine("MyProxy.Invoke Start")

         If TypeOf myMesg Is IMethodCallMessage Then
         End If
         If TypeOf myMesg Is IMethodReturnMessage Then
         End If

         Console.WriteLine("Message Properties")
         Dim myDictionary As IDictionary = myMesg.Properties
         Dim myEnum As IDictionaryEnumerator = CType(myDictionary.GetEnumerator(), IDictionaryEnumerator)

         While myEnum.MoveNext()
            Dim myKey As Object = myEnum.Key
            Dim myKeyName As String = myKey.ToString()
            Dim myValue As Object = myEnum.Value

            Console.WriteLine( "{0} : {1}", myKeyName, myEnum.Value)
            If myKeyName = "__Args" Then
               Dim myArgs As Object() = CType(myValue, Object())
               Dim myInt As Integer
               For myInt = 0 To myArgs.Length - 1
                  Console.WriteLine(  "arg: {0} myValue: {1}", myInt, myArgs(myInt))
               Next myInt
            End If
            If myKeyName = "__MethodSignature" And Not (myValue Is Nothing) Then
               Dim myArgs As Object() = CType(myValue, Object())
               Dim myInt As Integer
               For myInt = 0 To myArgs.Length - 1
                  Console.WriteLine("arg: {0} myValue: {1}", myInt, myArgs(myInt))
               Next myInt
            End If
         End While

         Console.WriteLine("myUrl1 {0} object URI{1}", myUrl, myObjectURI)

         myDictionary("__Uri") = myUrl
         Console.WriteLine("URI {0}", myDictionary("__URI"))

         Dim myRetMsg As IMessage = myMessageSink.SyncProcessMessage(myMesg)

         If TypeOf (myRetMsg) Is IMethodReturnMessage Then
            Dim myMethodReturnMessage As IMethodReturnMessage = CType(myRetMsg, IMethodReturnMessage)
         End If

         Console.WriteLine("MyProxy.Invoke - Finish")
         Return myRetMsg
      End Function 'Invoke
   End Class 'MyProxy

   ' Main class that drives the whole sample
   Public Class ProxySample
      <PermissionSet(SecurityAction.LinkDemand)> _
      Public Shared Sub Main()
         ChannelServices.RegisterChannel(New HttpChannel())

         Console.WriteLine("Remoting Sample:")

         Console.WriteLine("Generate a new MyProxy using the Type")
         Dim myType As Type = GetType(MyHelloService)
         Dim myUrl1 As String = "http://localhost/myServiceAccess.soap"
         Dim myProxy As New MyProxy(myType, myUrl1)

         Console.WriteLine("Obtain the transparent proxy from myProxy")
         Dim myService As MyHelloService = CType(myProxy.GetTransparentProxy(), MyHelloService)

         Console.WriteLine("Calling the Proxy")
         Dim myReturnString As String = myService.myFunction("bill")

         Console.WriteLine("Checking result : {0}", myReturnString)

         If myReturnString = "Hi there bill, you are using .NET Remoting" Then
            Console.WriteLine("myService.HelloMethod PASSED : returned {0}", myReturnString)
            Console.WriteLine("myService.HelloMethod FAILED : returned {0}", myReturnString)
         End If
      End Sub 'Main
   End Class 'ProxySample
End Namespace 'MyNameSpace


When a method call is made on the proxy, the remoting infrastructure provides the necessary support for passing the arguments to the actual object across the remoting boundaries, calling the actual object method with the arguments, and returning the results back to the client of the proxy object.

A remote method call is a message that goes from the client end to the server end and possibly back again. As it crosses remoting boundaries on the way, the remote method call passes through a chain of IMessageSink objects. Each sink in the chain receives the message object, performs a specific operation, and delegates to the next sink in the chain. The proxy object contains a reference to the first IMessageSink it needs to use to start off the chain.

For asynchronous calls, at the time of delegation, each sink provides a reply sink (another IMessageSink) that will be called by the next sink when the reply is on its way back.

Different types of sinks perform different operations, depending on the type of message object received. For example, one sink could cause a lock to be taken, another could enforce call security, another could perform flow call control and reliability services, and yet another could transport the call to a different AppDomain, process, or computer. Two or more message sinks in the chain can interact with each other in regard to each specific action.

Notes to Implementers

It is important to note that code implementing the current interface must provide implementations for both SyncProcessMessage(IMessage) and AsyncProcessMessage(IMessage, IMessageSink), since synchronous calls can be converted to asynchronous calls and vice versa. Both methods must be implemented, even if the sink does not support asynchronous processing.


NextSink NextSink NextSink NextSink

Gets the next message sink in the sink chain.


AsyncProcessMessage(IMessage, IMessageSink) AsyncProcessMessage(IMessage, IMessageSink) AsyncProcessMessage(IMessage, IMessageSink) AsyncProcessMessage(IMessage, IMessageSink)

Asynchronously processes the given message.

SyncProcessMessage(IMessage) SyncProcessMessage(IMessage) SyncProcessMessage(IMessage) SyncProcessMessage(IMessage)

Synchronously processes the given message.

Applies to