Explicit connection actions in multiparty session types

This work extends asynchronous multiparty session types (MPST) with explicit connection actions to support protocols with op- tional and dynamic participants. The actions by which endpoints are connected and disconnected are a key element of real-world protocols that is not treated in existing MPST works. In addition, the use cases motivating explicit connections often require a more relaxed form of mul- tiparty choice: these extensions do not satisfy the conservative restric- tions used to ensure safety in standard syntactic MPST. Instead, we de- velop a modelling-based approach to validate MPST safety and progress for these enriched protocols. We present a toolchain implementation, for distributed programming based on our extended MPST in Java, and a core formalism, demonstrating the soundness of our approach. We discuss key implementation issues related to the proposed extensions: a practi- cal treatment of choice subtyping for MPST progress, and multiparty correlation of dynamic binary connections

An automaton over data words that captures EMSO logic

We develop a general framework for the specification and implementation of systems whose executions are words, or partial orders, over an infinite alphabet. As a model of an implementation, we introduce class register automata, a one-way automata model over words with multiple data values. Our model combines register automata and class memory automata. It has natural interpretations. In particular, it captures communicating automata with an unbounded number of processes, whose semantics can be described as a set of (dynamic) message sequence charts. On the specification side, we provide a local existential monadic second-order logic that does not impose any restriction on the number of variables. We study the realizability problem and show that every formula from that logic can be effectively, and in elementary time, translated into an equivalent class register automaton

Distributed Implementation of Message Sequence Charts

International audienc

Automata and Logics for Concurrent Systems: Realizability and Verification

Automata are a popular tool to make computer systems accessible to formal methods. While classical finite automata are suitable to model sequential boolean programs, models of concurrent systems involve several interacting processes and extend finite-state machines in various respects. This habilitation thesis surveys several such extensions, including pushdown automata with multiple stacks, communicating automata with fixed, parameterized, or dynamic communication topology, and automata running on words over infinite alphabets. We focus on two major questions of classical automata theory, namely realizability (asking whether a specification has an automata counterpart) and model checking (asking whether a given automaton satisfies its specification)

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

Realizability of Dynamic MSC Languages

We introduce dynamic communicating automata (DCA), an extension of communicating finite-state machines that allows for dynamic creation of processes. Their behavior can be described as sets of message sequence charts (MSCs). We consider the realizability problem for DCA: given a dynamic MSC grammar (a high-level MSC specification), is there a DCA defining the same set of MSCs? We show that this problem is EXPTIME-complete. Moreover, we identify a class of realizable grammars that can be implemented by finite DCA