State machines for large scale computer software and systems

1998

When designing and implementing complex computer sys tems powerful description techniques are needed that allow the repre sentation of hardware and software components at various abstraction levels and support re nement during the development process These techniques should be formal in order to support mathematical reason ing about systems properties while at the same time they should be operational so as to facilitate comprehension and implementation of the system In this paper we propose Object based Abstract State Machines ObASM an extension of Abstract State Machines ASM ASM are an operational formalism that has been successfully applied to the description of hard ware and software systems ObASM are adding a notion of locality of state and the concept of communication between loosely coupled agents These extensions are designed to be minimal additions to the traditional ASM formulation preserving their simplicity while at the same time signi cantly enhancing their modeling powe...

Zenodo (CERN European Organization for Nuclear Research), 2008

Science of Computer Programming

Distributed programs are known to be extremely difficult to implement, test, verify, and maintain. This is due in part to the large number of possible unforeseen interactions among components, and to the difficulty of precisely specifying what the programs should accomplish in a formal language that is intuitively clear to the programmers. We discuss here a methodology that has proven itself in building a state of the art implementation of Multi-Paxos and other distributed protocols used in a deployed database system. This article focuses on the logical foundations as well as the basic ideas of formal EventML programming, illustrated by implementing a fault-tolerant consensus protocol and showing how we prove its safety properties with the Nuprl proof assistant.

2004

We survey applications of the Abstract State Machines (ASM) method for high-level system modeling and for well-documented refinements of abstract models to code.

2003

We introduce a logic for sequential, non distributed Abstract State Machines. Unlike other logics for ASMs which are based on dynamic logic, our logic is based on atomic propositions for the function updates of transition rules. We do not assume that the transition rules of ASMs are in normal form, for example, that they concern distinct cases. Instead we allow structuring concepts of ASM rules including sequential composition and possibly recursive submachine calls. We show that several axioms that have been proposed for reasoning about ASMs are derivable in our system and that the logic is complete for hierarchical (non-recursive) ASMs.

Electronic Notes in Theoretical Computer Science, 2008

We study distributed state space generation on a cluster of workstations. It is explained why state space partitioning by a global hash function is problematic when states contain variables from unbounded domains, such as lists or other recursive datatypes. Our solution is to introduce a database which maintains a global numbering of state values. We also describe tree-compression, a technique of recursive state folding, and show that it is superior to manipulating plain state vectors.

2008

In previous papers [5], [6] we describe an event-based UML state machine execution engine as well as a Microsoft Visio-based visual editor that has many benefits over the built-in JADE FSM (Finite State Machine) behaviour model. These benefits are an integration of message handling, timeouts, exceptions and the use of hierarchy and common action factoring to reduce the complexity of behaviour construction, while ultimately improving system scalability. In that work we engineered a consistent, largely self-contained component, with several key properties, but relatively incomplete integration with other JADE behaviour mechanisms. Since then, we have developed a new Hierarchical State Machine (HSM) model that shares many of the same goals of reducing the complexity of developing protocols and behaviours, but is a vastly improved companion to JADE. It leverages the newer JADE Composite Behaviour and offers substantial improvements over the JADE FSM. Furthermore, we describe a new Java ...

Annals of Mathematics and Artificial Intelligence, 2017

We develop a logic which enables reasoning about single steps of nondeterministic and parallel Abstract State Machines (ASMs). Our logic builds upon the unifying logic introduced by Nanchen and Stärk for reasoning about hierarchical (parallel) ASMs. Our main contribution is the handling of non-determinism within the logical formalism. We do this without sacrificing the completeness of the logic for statements about single steps of non-deterministic and parallel ASMs, such as invariants of rules, consistency conditions for rules, or step-by-step equivalence of rules. Moreover, we show that the proposed one-step logic can be easily extended to a multiple-step logic which enables reasoning about concurrent ASMs.

Laboratorio di Ingegneria del Software, …

This paper proposes a methodology for the development of distributed real-time (RT) systems using the Communicating Real-Time State Machines (CRSMs) formal specification language. The methodology is novel in that it addresses complex systems by extending CRSMs with concepts borrowed from Statecharts, and favours timing predictability through a holistic integration of an RT system and its operating software, i.e., message-based runtime executive. A full life cycle is established where all the development phases are unified by a common runtime representation based on actors used both for prototyping and temporal analysis and for final implementation. The paper describes the methodology and shows its practical use through examples. Java is the implementation language.

Lecture Notes in Computer Science, 2016

We develop a logic which enables reasoning about single steps of non-deterministic parallel Abstract State Machines (ASMs). Our logic builds upon the unifying logic introduced by Nanchen and Stärk for reasoning about hierarchical (parallel) ASMs. Our main contribution to this regard is the handling of non-determinism (both bounded and unbounded) within the logical formalism. Moreover, we do this without sacrificing the completeness of the logic for statements about single steps of non-deterministic parallel ASMs, such as invariants of rules, consistency conditions for rules, or step-by-step equivalence of rules.