Testing Whether a Remote MessageQueue Exists (using C#)

Question

How can I tell whether a remote message queue exists? The documentation states that the "Exists" method does not work for remote machines.

The following is not valid (I know the queue path is accurate since I am able to send messages to the queue):

if (!MessageQueue.Exists(@"FormatName:Direct=TCP:192.168.2.58\Private$\MyQueue"))
  throw new InvalidOperationException("Queue does not exist");

The problem is that sending a message to a network address that does not have a listening queue behind it does not cause an exception. Having an exception thrown for an invalid queue address is critical to our application.

Solution

There is an article about this:

Frank's alternative approach is to make use of other features that MSMQ provides, such as negative acknowledgements messages with administration queues.

What should happen is that either:

• the message will be delivered successfully to the destination queue
• a negative acknowledgement (NACK) will be returned to the administration queue with a class of "The destination queue does not exist." (MQMSG_CLASS_NACK_BAD_DST_Q) Alternatively you could use negative source journaling and, on failure to deliver, should see the same class of NACK in the corresponding "Dead-letter messages" system queue.

In summary, don't check if the queue exists but instead handle the non-delivery of the message should it turn out that the queue doesn't exist.

http://blogs.msdn.com/johnbreakwell/archive/2008/07/31/checking-if-msmq-queues-exist-is-hard-work-so-should-you-bother.aspx