MessageQueue::Receive Method ()

.NET Framework (current version)

Receives the first message available in the queue referenced by the MessageQueue. This call is synchronous, and blocks the current thread of execution until a message is available.

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

Syntax

C++

public:
Message^ Receive()

Return Value

Type: System.Messaging::Message^

A Message that references the first message available in the queue.

Exceptions

Exception	Condition
MessageQueueException	An error occurred when accessing a Message Queuing method.

Remarks

Use this overload to receive a message from a queue, or wait until there are messages in the queue.

The Receive method allows for the synchronous reading of a message, thereby removing it from the queue. Subsequent calls to Receive will return the messages that follow in the queue, or new, higher priority messages.

To read the first message in a queue without removing it from the queue, use the Peek method. The Peek method always returns the first message in the queue, so subsequent calls to the method return the same message unless a higher priority message arrives in the queue.

Use a call to Receive when it is acceptable for the current thread to be blocked while it waits for a message to arrive in the queue. Because this overload of the Receive method specifies an infinite time-out, the application might wait indefinitely. If the application processing should continue without waiting for the message, consider using the asynchronous method, BeginReceive.

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 receives a message from a queue and outputs information about that message to the screen.

C++

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

using namespace System;
using namespace System::Messaging;

// This class represents an object the following example 
// sends to a queue and receives from a queue.
ref class Order
{
public:
   int orderId;
   DateTime orderTime;
};


/// <summary>
/// Provides a container class for the example.
/// </summary>
ref class MyNewQueue
{
public:

   //*************************************************
   // Sends an Order to a queue.
   //*************************************************
   void SendMessage()
   {
      // Create a new order and set values.
      Order^ sentOrder = gcnew Order;
      sentOrder->orderId = 3;
      sentOrder->orderTime = DateTime::Now;

      // Connect to a queue on the local computer.
      MessageQueue^ myQueue = gcnew MessageQueue( ".\\myQueue" );

      // Send the Order to the queue.
      myQueue->Send( sentOrder );
      return;
   }

   //*************************************************
   // Receives a message containing an Order.
   //*************************************************
   void ReceiveMessage()
   {
      // Connect to the a queue on the local computer.
      MessageQueue^ myQueue = gcnew MessageQueue( ".\\myQueue" );

      // Set the formatter to indicate body contains an Order.
      array<Type^>^p = gcnew array<Type^>(1);
      p[ 0 ] = Order::typeid;
      myQueue->Formatter = gcnew XmlMessageFormatter( p );
      try
      {
         // Receive and format the message. 
         Message^ myMessage = myQueue->Receive();
         Order^ myOrder = static_cast<Order^>(myMessage->Body);

         // Display message information.
         Console::WriteLine( "Order ID: {0}", myOrder->orderId );
         Console::WriteLine( "Sent: {0}", myOrder->orderTime );
      }
      catch ( MessageQueueException^ ) 
      {
         // Handle Message Queuing exceptions.
      }
      // Handle invalid serialization format.
      catch ( InvalidOperationException^ e ) 
      {
         Console::WriteLine( e->Message );
      }

      // Catch other exceptions as necessary.
      return;
   }
};

//*************************************************
// Provides an entry point into the application.
//         
// This example sends and receives a message from
// a queue.
//*************************************************
int main()
{
   // Create a new instance of the class.
   MyNewQueue^ myNewQueue = gcnew MyNewQueue;

   // Send a message to a queue.
   myNewQueue->SendMessage();

   // Receive a message from a queue.
   myNewQueue->ReceiveMessage();
   return 0;
}

Version Information

.NET Framework
Available since 1.1