I started looking into MSMQ very recently so i have basic doubts . If two application needs to communicate lets say server and client I think both will share the same MQ address and when the client update then the Server will be having the MSMQ watcher which will listen to the message pick and use it. So according to me there are three component we need
Client - which knows the Queue location
Queue watcher - which watches the queue
service -- to which queue watcher will send the message to