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In today's distributed computing environment, the coordination of concurrent processes and the coordination of resource sharing are of critical importance. Consequently, much effort has been focused on the modeling of problems of coordination and concurrency. In this paper we describe a software environment (SPANNER) for the specification and analysis of such problems. In the SPANNER environment, one can formally produce a specification of a distributed computing problem, and then verify its "correctness" through reachability analysis and simulation. SPANNER is based on a finite state machine model called the selection/resolution model. We illustrate the capabilities of SPANNER by specifying and analyzing two classical coordination problems: 1) the dining philosophers; and 2) Dijkstra's concurrent programming problem. In addition to discussing these specific problems, our intention is also to focus on some of the more recently implemented capabilities of the SPANNER system such as process types and cluster variables. [ABSTRACT FROM AUTHOR]

Computations of distributed systems are extremely difficult to specify and verify using traditional techniques because the systems are inherently concurrent, asynchronous, and nondeterministic. Furthermore, computing nodes in a distributed system may be highly independent of each other, and the entire system may lack an accurate global clock. In this paper, we develop an event-based model to specify formally the behavior (the external view) and the structure (the internal view) of distributed systems. Both control-related and data-related properties of distributed systems are specified using two fundamental relationships among events: the "precedes" relation, representing time order; and the "enables" relations, representing causality. No assumption about the existence of a global clock is made in the specifications. The specification technique has a rather wide range of applications. Examples from different classes of distributed systems, include communication systems, process control systems, and a distributed prime number generator, are used to demonstrate the power of the technique. The correctness of a design can be proved before implementation by checking the consistency between the behavior specification and the structure specification of a system. Both safety and liveness properties can be specified and verified. Furthermore, since the specification technique defines the orthogonal properties of a system separately, each of them can then be verified independently. Thus, the proof technique avoids the exponential state-explosion problem found in state-machine specification techniques. [ABSTRACT FROM AUTHOR]