Input Tools as a Basis for Communicating Processes

A model of communicating parallel processes, based on high-level input functions, is introduced. It is called the input tool process model. In this model every process contains an input rule which specifies in an input expression the processes from which it expects input. Depending on the input some action takes place inside the tool process and as a result messages may be sent to the outside world. Because senders and receivers may specify each other with different degrees of identification the model supports very general classes of communication. It is for instance very suitable to utility processes and service routines in operating systems, for communication between system components and between user programs and system components, as well as for user programs communicating with each other. The tool process model is also applicable to nets of processes each running on their own processor. No special primitives for synchronization are needed, because the latter is accomplished implicitly by the input specification.