Message Queue

Message queues can also be used as synchronization object also.
In these kind of cases there is no payload, some bodya will just wait on the messge queue.
When message is received thread/process can continue their work.

Same thing is persent in the J Jobs. Where other J need to wait for ther other modules to complete the activity only then you can mark the job as competed. In that case J would be waiting for the message. Other module like I will send the message, then we will mark the job as competed.

In pSOS we have two types of queue, first one is the one having 4 long words as playload, Most of the embedded system these are more then eough to do the work. As we work of the physical address in single process address space.

But pSOS also has one more queue which is like same as System V IPC queue.