IMessageSink.cs

using System.Runtime.InteropServices;
using System.Security;

namespace System.Runtime.Remoting.Messaging
{
    [ComVisible(true)]
    public interface IMessageSink
    {
        IMessageSink NextSink
        {
            [SecurityCritical]
            get;
        }

        [SecurityCritical]
        IMessage SyncProcessMessage(IMessage msg);

        [SecurityCritical]
        IMessageCtrl AsyncProcessMessage(IMessage msg, IMessageSink replySink);
    }
}