An algebraic semantics of Message Sequence Charts

Message Sequence Charts is a graphical and textual language for the description and speciication of the interactions between system components and their environment. The language is standardized by the ITU-TS (the Telecommunication Standardization section of the International Telecommunication Union, the former CCITT). The main area of application for Message Sequence Charts is as an overview speciication of the communication behavior of real time systems, in particular telecommunication switching systems. Message Sequence Charts may be used for requirement speciication, interface spec-iication, simulation and validation, test case speciication and documentation of real time systems. In this paper we present a formal semantics of Message Sequence Charts exploiting techniques from process algebra. This semantics is proposed for standardization within the ITU-TS. We start with the semantics of the core language of Message Sequence Charts, Basic Message Sequence Charts, and subsequently add other features such as process creation and termination, reenement and timer handling.