Synthesizing decentralized components from a variant of live sequence charts

Live sequence charts (LSC) is a visual, executable, language for the modeling of reactive systems. Each chart depicts an inter-object scenario arising in the modeled system, partitioned into two: a monitored prechart, and a main chart. Despite the intuitive use of the language, complications arise when one wants to implement an LSC specification with decentralized components. In this paper, we introduce a variant of LSC, called distributed LSC (dLSC), which is targeted for the modeling and synthesis of decentralized systems, composed of several interacting components. While LSCs are commonly interpreted in terms of an interleaved execution of the scenarios in a sequential run, dLSCs employ partially ordered runs. We investigate the expressive power of dLSC compared to an established model of concurrent systems, namely, Petri nets, and show that dLSCs are, computationally, strictly more expressive than low-level Petri nets and subsumed by higher-level Petri nets. Specifically, we present an algorithm that synthesizes, given a dLSC specification, an equivalent token history net, which can serve as an executable implementation of the specification. Most importantly, the implementation is decentralized - components can be automatically extracted from the net. The synthesis of Petri-net components from a dLSC specification is supported by a tool.