Michał Wypych

Simulation of Multi-agent Systems with Alvis Toolkit

The paper presents a method of using the Alvis formal modelling language and related software to model and simulate multi-agent systems. The approach has been illustrated with an example of a railway traffic management system for a real train station. One of the main advantages of this approach is the possibility of including artificial intelligence (AI) systems encoded in Haskell into Alvis models. Moreover, Alvis models can be developed at the level very close to the final implementation of the corresponding real system. Thus simulation logs can be treated as a virtual prototype logs.

Communication between agents in Alvis language

Concurrent systems are composed of a set of subsystems (processes, threads etc.) that must communicate between themselves to meet the system requirements. Modelling and programming languages provide different communication modes to handle synchronous and/or asynchronous communication between subsystems. The paper provides a survey of communication modes introduced to the Alvis modelling language and discusses how the communication modes may be used while modelling embedded systems.

Generation of Java code from Alvis model

Alvis is a formal language that combines graphical modelling of interconnections between system entities (called agents) and a high level programming language to describe behaviour of any individual agent. An Alvis model can be verified formally with model checking techniques applied to the model LTS graph that represents the model state space. This paper presents transformation of an Alvis model into executable Java code. Thus, the approach provides a method of automatic generation of a Java application from formally verified Alvis model.

Modelling and Verification of Real-Time Systems with Alvis

Alvis is a formal language specifically intended for modelling systems consisting of concurrently operating units. By default, the time dependencies of the modelled system are taken into account, what is expressed by the possibility of determining the duration of each statement performed by the model components. This makes Alvis suitable for modelling and verification of real-time systems. The paper focuses on Alvis time models. The article outlines the syntax and semantics of such models, and discusses the main issues related to the generation of Labelled Transition Systems for time models. Particular attention was paid to tools that support the verification process.

Supporting BPMN Process Models with UML Sequence Diagrams for Representing Time Issues and Testing Models

Business Process Model and Notation is a standard for process modeling. However, such models do not specify the time issues such as time of performing tasks or time of utilizing the resources. We propose the complementary UML sequence model generated from the BPMN model. Such a model can support time specification and provide direct time visualization. It is also suitable for validation in terms of time matters by domain experts as well as can be used to estimate and test methods in the systems based on random examination of the critical paths.

Priority management in Alvis language

Priority management is crucial to the development of correct real-time systems. Applications of formal methods in the development process require to choose a suitable formalism that is capable of dealing with different priority management algorithms. The paper deals with priority management in the Alvis modelling language. One of the advantages of Alvis is its Haskell middle-stage representation that can be freely modified by a programmer. This provides an opportunity to include a user-defined algorithm for managing priorities into a model. The paper shows how such algorithms may be implemented and included into Alvis models.

Extension of Alvis compiler front-end

Alvis is a formal modelling language that enables possibility of verification of distributed concurrent systems. An Alvis model semantics finds expression in an LTS graph (labelled transition system). Execution of any language statement is expressed as a transition between formally defined states of such a model. An LTS graph is generated using a middle-stage Haskell representation of an Alvis model. Moreover, Haskell is used as a part of the Alvis language and is used to define parameters’ types and operations on them. Thanks to the compiler’s modular construction many aspects of compilation of an Alvis model may be modified. Providing new plugins for Alvis Compiler that support languages like Java or C makes possible using these languages as a part of Alvis instead of Haskell. The paper presents the compiler internal model and describes how the default specification language can be altered by new plugins.