MessageQueue::EndReceive Method (IAsyncResult^)

.NET Framework (current version)

Completes the specified asynchronous receive operation.

Namespace: System.Messaging
Assembly: System.Messaging (in System.Messaging.dll)

Syntax

public:
Message^ EndReceive(
	IAsyncResult^ asyncResult
)

Parameters

asyncResult: Type: System::IAsyncResult^
The IAsyncResult that identifies the asynchronous receive operation to finish and from which to retrieve an end result.

Return Value

Type: System.Messaging::Message^

The Message associated with the completed asynchronous operation.

Exceptions

Exception	Condition
ArgumentNullException	The asyncResult parameter is null.
ArgumentException	The syntax of the asyncResult parameter is not valid.
MessageQueueException	An error occurred when accessing a Message Queuing method.

Remarks

When the ReceiveCompleted event is raised, EndReceive(IAsyncResult^) completes the operation that was initiated by the BeginReceive call. To do so, EndReceive(IAsyncResult^) receives the message.

BeginReceive can specify a time-out, which causes the ReceiveCompleted event to be raised if the time-out occurs before a message appears in the queue. When a time-out occurs without a message arriving in the queue, a subsequent call to EndReceive(IAsyncResult^) throws an exception.

EndReceive(IAsyncResult^) is used to read (removing from the queue) the message that caused the ReceiveCompleted event to be raised.

If you want to continue to asynchronously receive messages, you can again call BeginReceive after calling EndReceive(IAsyncResult^).

The following table shows whether this method is available in various Workgroup modes.

Workgroup mode	Available
Local computer	Yes
Local computer and direct format name	Yes
Remote computer	No
Remote computer and direct format name	Yes

Examples

The following code example chains asynchronous requests. It assumes there is a queue on the local computer called "myQueue". The Main function begins the asynchronous operation that is handled by the MyReceiveCompleted routine. MyReceiveCompleted processes the current message and begins a new asynchronous receive operation.

C++

#using <system.dll>
#using <system.messaging.dll>

using namespace System;
using namespace System::Messaging;
using namespace System::Threading;

ref class MyNewQueue
{
public:

   // Define static class members.
   static ManualResetEvent^ signal = gcnew ManualResetEvent( false );
   static int count = 0;

   // Provides an event handler for the ReceiveCompleted
   // event.
   static void MyReceiveCompleted( Object^ source, ReceiveCompletedEventArgs^ asyncResult )
   {
      try
      {
         // Connect to the queue.
         MessageQueue^ mq = dynamic_cast<MessageQueue^>(source);

         // End the asynchronous receive operation.
         mq->EndReceive( asyncResult->AsyncResult );
         count += 1;
         if ( count == 10 )
         {
            signal->Set();
         }

         // Restart the asynchronous receive operation.
         mq->BeginReceive();
      }
      catch ( MessageQueueException^ ) 
      {
         // Handle sources of MessageQueueException.
      }

      // Handle other exceptions.
      return;
   }
};

// Provides an entry point into the application.
//         
// This example performs asynchronous receive
// operation processing.
int main()
{
   // Create an instance of MessageQueue. Set its formatter.
   MessageQueue^ myQueue = gcnew MessageQueue( ".\\myQueue" );
   array<Type^>^p = gcnew array<Type^>(1);
   p[ 0 ] = String::typeid;
   myQueue->Formatter = gcnew XmlMessageFormatter( p );

   // Add an event handler for the ReceiveCompleted event.
   myQueue->ReceiveCompleted += gcnew ReceiveCompletedEventHandler( MyNewQueue::MyReceiveCompleted );

   // Begin the asynchronous receive operation.
   myQueue->BeginReceive();
   MyNewQueue::signal->WaitOne();

   // Do other work on the current thread.
   return 0;
}

Version Information

.NET Framework
Available since 1.1