Synchronous Message Passing
Synchronous Message Passing
The threads of the previous sections communicated by shared variables. We had to using locking protocols to ensure non-interference during access to shared variables. Pure message passing concurrent programs do not share variables. Variables are encapsulated by processes and processes may only communicate by sending and receiving messages.
There are many different message passing models. In this section, the synchronous message passing model is used. It is similar to that proposed by Hoare in his CSP (Communicating Sequential Processes) model which was subsequently used as the basis for the programming language Occam. Occam is the language used to program the Transputer.