Browsing parallel process networks

Abstract

A hypertext is a non-linearly organized, linked information structure, designed to be interactively browsed. In this report we demonstrate the use of a hypertext system for visualization and simulation of the parallel control flow and message network of concurrent programs. Instead of constructing code browsers as special-purpose window systems that understand the syntax and semantics of particular languages, we present a general approach that relies on the (usually extensive) browsing facilities of a hypertext system. Language-specific browsers can be realized by generating filters to convert program text into hypertext documents. We demonstrate our filter approach specifically with the parallel language CSP and the α Trellis hypertext system. α Trellis employs the dual nature of Petri nets to express formally in one structure both the linked information elements of a document and the reader/document interactions during browsing. α Trellis is especially appropriate for parallel program browsing because Petri nets are a natural concurrency model, and because it offers state-space analysis for deadlocks and other program properties. α Trellis-based program browsers for other parallel languages can be produced by designing appropriate Petri net translations.