How can I suspend my whole system to wait for something?

[fanji...@gmail.com]

Dear everyone,

I am working on a big simulation project, it has many modules.

 i want to deliver some information of the system  to another implement(PRISM), and PRISM will compute something and then send back its response, then i want to continue handling the message, the problem is, when i deliver the message to PRISM, the execution was continued in my handling procedure, which as i said, should be suspended till the reply recieved, how i can suspend the execution of the message handler until i receive a reply,

i am looking forward for your reply.

Sincerely,

Jenney