Mandana Vaziri, Joshua A. Tauber, and Michael J. Tsai. Systematic Removal of Nondeterminism for Code Generation in I/O Automata. Technical Report MIT-LCS-TR-960, Massachusetts Institute of Technology, Cambridge, MA, July 2004.
The Input/Output (I/O) automaton model, developed by Lynch and Tuttle, models components in asynchronous concurrent systems as labeled transition systems. IOA is a precise language for describing I/O automata and for stating their properties. A toolset is being developed for IOA, to support distributed software design and implementation. One of the tools consists of a user-assisted code generator from IOA into an imperative programming language such as C or Java.
One aspect that distinguishes IOA programs from programs written in imperative languages, is the presence of nondeterminism, which comes in the form of explicit nondeterministic statements and implicit scheduling choices made during execution. Code generation therefore consists partially 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 nondeterminism explicit. The programmer can then replace all explicit nondeterminism with deterministic statements, prior to code generation. We also describe this transformation at a semantic level, i.e., at the level of the I/O automaton mathematical model. We show that the transformation defined at the IOA level conforms to the one at the semantic level.