Towards a Theory of Regular MSC Languages

Message Sequence Charts (MSCs) are an attractive visual formalism widely used to capture system requirements during the earlydesign stages in domains such as telecommunication software. It isfruitful to have mechanisms for specifying and reasoning about collections of MSCs so that errors can be detected even at the requirements level. We propose, accordingly, a notion of regularity for collections of MSCs and explore its basic properties. In particular, weprovide an automata-theoretic characterization of regular MSC languages in terms of finite-state distributed automata called boundedmessage-passing automata. These automata consist of a set of sequential processes that communicate with each other by sending andreceiving messages over bounded FIFO channels. We also provide alogical characterization in terms of a natural monadic second-orderlogic interpreted over MSCs.A commonly used technique to generate a collection of MSCs isto use a Message Sequence Graph (MSG). We show that the class oflanguages arising from the so-called locally synchronized MSGs constitute a proper subclass of the languages which are regular in our sense.In fact, we characterize the locally synchronized MSG languages asthe subclass of regular MSC languages that are finitely generated

A theory of regular MSC languages

Message sequence charts (MSCs) are an attractive visual formalism widely used to capture system requirements during the early design stages in domains such as telecommunication software. It is fruitful to have mechanisms for specifying and reasoning about collections of MSCs so that errors can be detected even at the requirements level. We propose, accordingly, a notion of regularity for collections of MSCs and explore its basic properties. In particular, we provide an automata-theoretic characterization of regular MSC languages in terms of finite-state distributed automata called bounded message-passing automata. These automata consist of a set of sequential processes that communicate with each other by sending and receiving messages over bounded FIFO channels. We also provide a logical characterization in terms of a natural monadic second-order logic interpreted over MSCs. A commonly used technique to generate a collection of MSCs is to use a hierarchical message sequence chart (HMSC). We show that the class of languages arising from the so-called bounded HMSCs constitute a proper subclass of the class of regular MSC languages. In fact, we characterize the bounded HMSC languages as the subclass of regular MSC languages that are finitely generated

Matching Specifications for Message Sequence Charts

Message sequence charts (MSC) are widely used in the early design of communication protocols. They allow describing the communication skeleton of a system. We consider a basic verification task for hierarchical MSCs, the matching problem via MSC templates. We characterize the complexity of checking properties which are expressible by and-or templates, resp. by LTL formulas. Both problems are shown to be PSPACE-complete

Logics on data words

We investigate logics on data words, i.e., words where each position is labelled by some propositions from a finite set and by some data values from an infinite domain. A basic motivation for the study of these logics, called data logics in this work, is that data words are a suitable model to represent traces of concurrent systems with unboundedly many interacting processes. In such representations data values stand for process IDs. Thus, data logics can be used to formulate requirements on such traces. We first study the expressivity and complexity of the satisfiability problem for these logics. Then, we investigate suitable models for concurrent systems with unboundedly many processes. Finally, we analyse the model checking problem for such systems in the case that data logics are used to specify system requirements. One of our main results is that, despite the bad properties of data logics with respect to satisfiability, there are important cases in which model checking with data logics has moderate complexity. Hence, our results motivate for further investigations with the aim to find interesting models and data logics which can be used in practical model checking tools