Proving safety and liveness of communicating processes with examples

A method is proposed for reasoning about safety and liveness properties of message passing networks. The method is hierarchical and is based upon combining the specifications of component processes to obtain the specification of a network. The inference rules for safety properties use induction on the number of messages transmitted; liveness proofs use techniques similar to termination proofs in sequential programs. We illustrate the method with two examples: concatenations of buffers to construct larger buffers and a special case of Stenning protocol for message communication over noisy channels

Proving safety and liveness of communicating processes with examples

A method is proposed for reasoning about safety and liveness properties of message passing networks. The method is hierarchical and is based upon combining the specifications of component processes to obtain the specification of a network. The inference rules for safety properties use induction on the number of messages transmitted; liveness proofs use techniques similar to termination proofs in sequential programs. We illustrate the method with two examples: concatenations of buffers to construct larger buffers and a special case of Stenning protocol for message communication over noisy channels

The Problem of Mutual Exclusion: A New Distributed Solution

In both centralized and distributed systems, processes cooperate and compete with each other to access the system resources. Some of these resources must be used exclusively. It is then required that only one process access the shared resource at a given time. This is referred to as the problem of mutual exclusion. Several synchronization mechanisms have been proposed to solve this problem. In this thesis, an effort has been made to compile most of the existing mutual exclusion solutions for both shared memory and message-passing based systems. A new distributed algorithm, which uses a dynamic information structure, is presented to solve the problem of mutual exclusion. It is proved to be free from both deadlock and starvation. This solution is shown to be economical in terms of the number of message exchanges required per critical section execution. Procedures for recovery from both site and link failures are also given