Uwe Glässer

High-level executable specification of the universal plug and play architecture

Recently, Microsoft took the lead in the development of a standard for peer-to-peer network connectivity of various intelligent appliances, wireless devices and PCs. It is called the Universal Plug and Play Device Architecture (UPnP). We construct a high-level abstract state machine (ASM) model for UPnP using AsmL. AsmL is an advanced ASM-based executable specification language that has been developed at Microsoft Research. It provides a modern specification environment that is object-oriented and component-based. AsmL is integrated into Microsoft Visual Studio, Word and COM.

On the Formal Semantics of SDL-2000: A Compilation Approach Based on an Abstract SDL Machine

In November 1999, a new version of SDL (Specification and Description Language) called SDL-2000 has passed ITU, an international standardization body for telecommunication. SDL is a fairly complex, graphical formal description technique for the development of distributed systems, and has been broadly used in industry for many years. Efforts to define the semantics of SDL-2000 formally have started early in 1998. By now, a draft formal semantics is available, which is determined to become the official formal SDL semantics after its approval in 2000. It is based on the formalism of Abstract State Machines (ASMs), which has been selected for several reasons including intelligibility and executability. n nThe formal semantics of SDL addresses the static semantics, transformation rules, and the dynamic semantics. The approach taken to define the dynamic semantics is particularly interesting. Although basically being operational, it differs from existing approaches in several ways. In this paper, we address and highlight some of these differences, using a simplified specification language called SSL instead of SDL. In defining a formal dynamic semantics for SSL, we formally describe an abstract machine, a compilation function mapping SSL specifications to code of this machine, and an operational definition of the set of initial states, using ASM as the underlying formalism. Furthermore, we present in some detail the semantics of SSL procedure calls.

Towards a New Formal SDL Semantics based on Abstract State Machines

With the year 2000 approaching, a new version of SDL called SDL-2000 is currently reaching maturity, and is expected to pass the standardization bodies shortly. Apart from the usual language maintenance, SDL-2000 will offer new features for exception handling and object-oriented data types. To capture these features formally, a new formal SDL semantics is being devised. In several meetings of ITU-T SG10/Q6, the essential design objectives have been clarified, and an outline of the behaviour model for SDL has been presented and discussed. A major concern in this discussion has been the demand for an executable model, which calls for an operational formalism with readily available tool support. Subsequent investigations have shown that Abstract State Machines (ASMs) meet this and all other design objectives, and therefore have been chosen as the underlying formalism. In this paper, ASMs are applied to define the behaviour model of a sample SDL specification formally, thereby illustrating the approach in general.

A Distributed Implementation of Flat Concurrent Prolog on Multi-Transputer Environments

FCP is a general purpose concurrent logic programming language. We describe a distributed implementation of FCP on a multi-transputer environment based on the design of a parallel FCP machine.

Knowledge Based Tools for Testability Checking

Caused by high complexity of todays systems, testing of digital circuits rises lots of problems, which imply difficult and time complex solutions using common computer aided technics. On the other hand, experts of the subject are able to solve these problems using their special, heuristic knowledge. Therefore it seems reasonable to use artificial intelligence applications to find new ways of solutions.

Flat concurrent Prolog on transputers

Abstract Flat Concurrent Prolog (FCP) is a general purpose logic programming language designed for concurrent programming and parallel execution. Staring with a concise introduction of the language and its underlying computational model we describe how to implement a distributed FCP interpreter on a transputer environment using OCCAM. Basic techniques we used for exploiting and controlling parallelism are explained in terms of an abstract architecture. The result of mapping this abstract model on transputers is presented as concrete architecture. Substantial design issues are considered in detail.

Software IP In Embedded Systems

IP-based hardware design became an important topic during the past years. There is an even older tradition of reuse of software components. In this contribution we try to address some key problems of software reuse. First of all, in a bottom-up approach we study some underlying communication techniques used to couple different software components. As the most general solution of this problem is CORBA (Common Object Request Broker Architecture) from our point of view, this technique is discussed briefly. From the bottom we move directly to the top. The most flexible way of handling reusable software IP is to deal with their abstract model. Following this approach, modules can be embedded to various target environments using standard synthesis methods. The problem of protecting property in this approach is not discussed in this chapter. We concentrate on how to combine modules that have been modelled in various languages. At least when using a language coupling approach strict support to define bridging semantics has to be provided. A very useful means for this purpose is given by the ASM (Abstract State Machine) method, which is shortly introduced in the chapter. When software IP has to be used this IP resides on various databases in most cases. We discuss, how design workflows can be defined that allow to access such remote IPs. The exchange format XML plays an important role in this context. Finally we discuss an application example: the application-specific synthesis of real-time operating systems (RTOS) and real-time communication systems (RCOS) from a library of reusable and highly generic software modules.

Computer-Aided Analysis and Validation of Heterogeneous System Specifications

In applications of formal methods, the problem of how to establish the correctness of the initial formalization step is an often underestimated aspect of the system design process. We propose a methodology based on the construction of a mathematical model which reflects the given system so closely that the correctness can be established by observation and experimentation (ground model). Complex technical systems are often heterogeneous, so that different system aspects are best modelled by means of different techniques. This leads to heterogeneous ground models. To achieve a consistent and coherent view of heterogeneous behavioural models, which is a prerequisite for any systematic analysis and validation, we introduce a common semantic framework (meta-model) based on the notion of Abstract State Machines. We exemplify our methodology by an industrial case study from automated manufacturing, the distributed control for a material flow system (MFS).

Dynamische Partitionierung Asynchroner Prozeßnetzwerke am Beispiel Paralleler Logischer Programmierung

Das abstrakte Modell reiner logischer Programmierung beinhaltet verschiedene Formen inharenter Parallelitat. Aus dem Bestreben, diese in konkreten Ausfuhrungmodellen fur parallele logische Programmiersprachen nutzbar zu machen, sind mehrere grundsatzlich verschiedene Ansaze zur parallelen logischen Programmierung hervorgegangen.