Describing Layered Communication Architecture in SDL Markup Language

Using Specification and Description Language (SDL) as a formal language for specification of requirements for the complex, real-time and distributed systems involving many concurrent activities, we have come to the idea of making the language independent of platforms and operating systems which may use it. Shortly, we have developed markup version of the SDL language, and named it SDL Markup Language. It is an XML-based version of the SDL-PR (Phrase Representation), an SDL textual notation. We use the language to specify the complex communications protocols, which are used in wide range of layered architectures. We provide the specification from the INRES protocol in SDL-ML

Real-Time Estelle

Estelle is one of the standardized Formal Description Techniques for the specification of communication protocols and distributed systems. Unfortunately, Estelle is not capable to express real-time requirements or characteristics of services or protocols which is especially important in the context of distributed multimedia systems. In this paper, we introduce an extension to Estelle called Real-Time Estelle that allows to describe real-time systems. We introduce the syntax of the new language and propose both an operational and a descriptive semantics. Examples show the usefulness of the approach. We also discuss ways to implement Real-Time Estelle specifications

From AADL Model to LNT Specification

The verification of distributed real-time systems designed by architectural languages such as AADL (Architecture Analysis and Design Language) is a research challenge. These systems are often used in safety- critical domains where one mistake can result in physical damages and even life loss. In such domains, formal methods are a suitable solution for rigorous analysis. This paper studies the formal verification of distributed real-time systems modelled with AADL. We transform AADL model to another specification formalism enabling the verification. We choose LNT language which is an input to CADP toolbox for formal analysis. Then, we illustrate our approach with the ”Flight Control System” case study

Language Constructs for Distributed Real-Time Programming

For many distributed applications, it is not sufficient for programs to be logically correct. In addition, they must satisfy various timing constraints. This paper discusses primitives that support the construction of distributed real-time programs. Our discussion is focused in two areas: timing specification and communication. To allow the specifications of timing constraints, we introduce the language constructs for defining temporal scope and specifying message deadline. We also identify communication primitives needed for real-time programming. The issues underlying the selection of the primitives are explained, including handling of timing exceptions. The primitives will eventually be provided as part of a distributed programming system that will be used to construct distributed multi-sensory systems

Active Databases for Communication Network Management

This paper has two purposes. First is to propose new database language-features for systems used in real-time management. These features enable the specification of change-traces, events and correlation among events, and they do so in a declarative set-oriented fashion. Second is to introduce network management as an important and interesting application of active distributed databases

TESL: A Model with Metric Time for Modeling and Simulation

Real-time and distributed systems are increasingly finding their way into critical embedded systems. On one side, computations need to be achieved within specific time constraints. On the other side, computations may be spread among various units which are not necessarily sharing a global clock. Our study is focused on a specification language - named TESL - used for coordinating concurrent models with timed constraints. We explore various questions related to time when modeling systems, and aim at showing that TESL can be introduced as a reasonable balance of expressiveness and decidability to tackle issues in complex systems. This paper introduces (1) an overview of the TESL language and its main properties (polychrony, stutter-invariance, coinduction for simulation), (2) extensions to the language and their applications

A TLA+ Formal Specification and Verification of a New Real-Time Communication Protocol

AbstractWe describe the formal specification and verification of a new fault-tolerant real-time communication protocol, called DoRiS, which is designed for supporting distributed real-time systems that use a shared high-bandwidth medium. Since such a kind of protocol is reasonably complex and requires high levels of confidence on both timing and safety properties, formal methods are useful. Indeed, the design of DoRiS was strongly based on formal methods, where the TLA+ language and its associated model-checker TLC were the supporting design tool. The protocol conception was improved by using information provided by its formal specification and verification. In the end, a precise and highly reliable protocol description is provided

Constructive tool design for formal languages : from semantics to executing models

Embedded, distributed, real-time, electronic systems are becoming more and more dominant in our lives. Hidden in cars, televisions, mp3-players, mobile phones and other appliances, these hardware/software systems influence our daily activities. Their design can be a huge effort and has to be carried out by engineers in a limited amount of time. Computer-aided modelling and design automation shorten the design cycle of these systems enabling companies to deliver their products sooner than their competitors. The design process is divided into different levels of abstraction, starting with a vague product idea (abstract) and ending up with a concrete description ready for implementation. Recently, research has started to focus on the system level, being a promising new area at which the product design could start. This dissertation develops a constructive approach to building tools for system-level design/description/modelling/specification languages, and shows the applicability of this method to the system-level language POOSL (Parallel Object-Oriented Specification Language). The formal semantics of this language is redefined and partly redeveloped, adding probabilistic features, real-time, inheritance, concurrency within processes, dynamic ports and atomic (indivisible) expressions, making the language suitable for performance analysis/modelling. The semantics is two-layered, using a probabilistic denotational semantics for stating the meaning of POOSL’s data layer, and using a probabilistic structural operational semantics for the process layer and architecture layer. The constructive approach has yielded the system-level simulation tool rotalumis, capable of executing large industrial designs, which has been demonstrated by two successful case studies—an ATM-packet switch (in conjunction with IBM Research at Z¨urich) and a packet routing switch for the Internet (in association with Alcatel/Bell at Antwerp). The more generally applicable optimisations of the execution engine (rotalumis) and the decisions taken in its design are discussed in full detail. Prototyping, where the system-level model functions as a part of the prototype implementation of the designed product, is supported by rotalumis-rt, a real-time variant of the execution engine. The viability of prototyping is shown by a case study of a learning infrared remote control, partially realised in hardware and completed with a system-level model. Keywords formal languages / formal specification / modelling languages / systemlevel design / embedded systems / real-time systems / performance analysis / discrete event simulation / probabilistic process algebra / design automation / prototyping / simulation tool

A model-based approach to the development of distributed control systems

Distributed Control Systems (DCS) are a class of application with specific characteristics. This type of system is used in industrial environments to control manufacturing processes. Usually they comprise a controller, a fieldbus network, and a set of Of-The-Shelf (OTS) components, interfacing process signals with real-time QoS requirements. In this paper we present a Model Driven Development (MDD) method that targets this category of systems. This method focuses on the critical stages of DCS development. Namely, the specification of system requirements, the choice of OTS modules and fieldbus system, and the validation of the design using real-time analysis tools. This MDD method uses the Unified modelling Language (UML) as support notation, including the extensions defined in the UML Profile for Schedulability, Performance and Time Specification.Fundação para a Ciência e Tecnologia; FEDER – Project METHODES (POSI/37334/CHS/2001)