WCF and MSMQ - Push messages from Queue to Services?

Question

I just want to find out if this is possible or whether I'm over complicating it.

I have a web application (Let's call it central) that needs to interact with a WCF service that's running on multiple workstations. ie The user will select the workstations to send messages to and the web application will need to do a call to each of the workstations. These workstations won't be online all the time and in the worst case there can be just over 600 workstations that messages will need to be sent to at a single time.

I'm thinking of having a separate WCF service running on the central machine that will function as a sort of "proxy" between the web app (central) and the workstations. The web app will then make a single call to this service with a list of messages, the service will then process this list and add the messages to a queue.

From what I've read so far, the workstations will need to poll this central queue for messages but this seems like it will increase overhead quite a bit. Is it possible to push the messages down to the workstation as they are added to the queue?

I've never used MSMQ before and I'm fairly new to WCF as well so if there's a simpler way of achieving this do tell.

Answer 1

I'm thinking of having a separate WCF service running on the central machine that will function as a sort of "proxy" between the web app (central) and the workstations

I don't see any problem with you using an additional service to act as a "proxy".

the workstations will need to poll this central queue for messages

I would probably advise that you have a central "inbox" of messages to process on the central server. The "proxy" then locally processes the inbox. Have the web site send the jobs to the proxy.

Push model

For the workstations, rather than having them read from the server, have the server send the messages to the workstations. Have a unique queue for each workstation and that queue be situated on the workstation itself. Have the service send the message targeted for the workstation to the workstation's queue. As each message from the central queue/inbox is processed by the proxy, the proxy removes said message from the queue and moves onto the next one.

MSMQ Performance

Generally in MSMQ it's better to do network writes than network reads for scaling reasons. A multitude of computers all reading from the same queue is hurtful to performance. In other words, have the "central" service write to the remote queues (MSMQ will take care of transmitting the message when the machine is available).

the workstations will need to poll this central queue for messages but this seems like it will increase overhead quite a bit

Correct. Use BeginRead . Polling is hurtful to CPU and/or a waste of a good thread.