Systematic Removal of Nondeterminism for Code Generation in I/O Automata

Abstract

The Input/Output (I/O) automaton model developed by Lynch and Tuttle models components in asynchronous concurrentsystems as labeled transition systems. IOA is a precise language for describing I/O automata and for stating their properties. A toolset is beingdeveloped for IOA to support distributed software design and implementation. One of the tools consists of a userassisted code generator fromIOA into an imperative programming language such as C or Java. One aspect that distinguishes IOA programs from programs written inimperative languages is the presence of nondeterminism which comesin the form of explicit nondeterministic statements and implicit scheduling choices made during execution. Code generation therefore consistspartially of systematically removing all forms of nondeterminism. In this paper, we describe our approach and design for code generation.We focus on the issue of removing implicit nondeterminism and specify a transformation on IOA programs that makes all nondeterminismexplicit. The programmer can then replace all explicit nondeterminismwith deterministic statements prior to code generation. We also describethis transformation at a semantic level i.e., at the level of the I/O automaton mathematical model. We show that the transformation definedat the IOA level conforms to the one at the semantic level.