在远程计算机上找不到MSMQ消息

Question

I have a WCF service that is set up to use MSMQ to transmit to a service on another machine. We are trying to move the client onto a different machine, but it's not working. Enabling the MSMQ.End2End event log gives us

Message with ID {6940f8fa-3d31-4db0-ae2b-59bc98c99f2c}\25321 was sent to queue DIRECT=OS:iisapp1-vvpm\private$\TransactionalEmailService/TransactionalEmail.Service.TransactionalEmailService.svc

which makes me think that it is working correctly from our machine, but we can't find any trace of it on the target machine. The service is not being invoked, and we can't find the message in the dead-letter queue (or anywhere else we can think of to look).

Also, running the code directly from Visual Studio on my machine causes it to work.

Changing the receiving queue to the DEV machine also causes the code to work, which makes me further think it's a problem with the receiving machine. (I just have no idea what)

UPDATE 1: I came back to it and noticed all the messages I tried to send in the transactional dead-letter queue. The error message is "the time-to-reach-queue has elapsed". Looking at the connection state, it's inactive, and sending another message won't cause it to become connected. I restart the machine, and it is "Connected" again. I try to send the message again, and look at the queue state. There are 12 messages, all of which are unacknowledged (0 are unprocessed).

Answer 1

So it started happening again once the the endpoint machine got restarted. I came across this article, which was the real solution:

http://blogs.msdn.com/b/johnbreakwell/archive/2007/02/06/msmq-prefers-to-be-unique.aspx

( In case the link goes away: )

It looks like there is an ID in MSMQ that is sent as part of the message. The remote host uses that ID as a key into a cache to determine who to send the ack back to. If you clone a machine, it gets the same value in the registry for that ID, which makes the other machine not know who to send it back to. So it will send it to the wrong machine, which will discard it, and the other machine will be stuck with a bunch of messages it keeps trying to send. This also explains why it just started working one day... the cache expired and the "correct" machine got put in as the endpoint.

Reinstalling MSMQ on the cloned machine fixes the issue.

Answer 2

I'm really not sure this may be the case here (I don't have any experience with WCF in the context of MSMQ), but one of the more common reasons of this kind of behaviour you're talking of is missing the obligatory camel casing on FormatName in your queue name when using a MessageQueue constructor (like 'FormatName:DIRECT=...'), or getting the name somehow wrong. The queue name in the message looks a bit odd with the svc ending, but that could just be a WCF thing? Hope this helps at least getting you on the right direction.

Answer 3

Not sure what to say here, but it works now. Reading some stuff helped point me to the status of the queue (click on Outgoing Queues under Features/Message Queueing). From there I found this KB article with a hotfix: http://support.microsoft.com/kb/976438 It didn't seem like it was applicable, but the symptoms people were having were all the same. Our guys tried to install it, but it failed and they didn't restart... but for some reason the message queues started working.

If someone comes along with some insight, I'll gladly upvote them or give them the bounty (if it's soon enough). But I'll just accept this as the answer for now.

Answer 4

This is usually caused by permissions on the remote queue, usual scenario is if you are using a private queue and this is accessed remotely by your wcf service.

Try using a public queue.