If: An Intermediate Representation and Validation Environment for Timed Asynchronous Systems

Computer networks are large and complex systems. The use of natural language to design and analyse communications protocols will lead to ambiguous representations. This inadequacy of the natural language gives rise to the many recent research works on formal description techniques (FDTs). FDTs are methods to define the behaviour of an information processing system in a language with formal syntax and semantics. FDT has been chosen as a basis for the design of protocol converter. A survey of existing widely accepted FDTs is presented. From this survey, a selection is made for an appropriate FDT to be used as the basis for future research work on FDT-based protocol converter.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The situation of telecommunications systems is rapidly evolving towards a state characterized by the presence of a multitude of services integrated in a single network structure. In order to ease their integration, it is important to provide an unambiguous description of the organization, of the functionality, and of the relationships existing among services. Since it is not possible to completely foresee the situation of services in the future, the description should be modular, so that the task of adding new services to an existing environment is simplified. Formal description techniques are languages designed to handle such descriptions. Their goal is to produce correct and unambiguous specifications, understanding and modeling the system and the domain within which it operates. Their input is a set of required statements and a conceptual overview of the system. Their output is a formal representation that captures the functional behavior. On the other hand, the throughput of physical networks is constantly growing, reaching the order of Gbit/s. In the meantime, services needing high throughput, like multimedia conferencing systems are being designed, creating a need for flexible, high performance communication systems. An important feature of new high speed services is their increased need for guarantees. Therefore, the use of powerful performance modeling techniques becomes of prime importance. Their goal is to obtain some notion of how the system will perform under a given set of conditions. Performance evaluation theorists have long been using system specifications to make a heuristic model of the system and then an analysis of the model. When system specifications exist, the question arises whether a more direct path to performance analysis can be found. Our scope is to provide a methodology that fully and consistently integrates formal specification and performance evaluation. A problem is that many of the bottlenecks and impediments to smooth data flow have to do with implementation issues not directly dealt within the system specification itself. Therefore, prior to generating a performance model, the formal specification should be enhanced with the relevant non-functional information. It is essential to assure a smooth specification of the non-functional information. Thus, it is necessary to consistently add this information to the formal specification. Besides, the extended formal method should focus on conserving the semantics of the original one, and on providing a coherent extension of the semantics and syntax for the new concepts. Since all relevant required information is integrated within the formal extended representation, we provide a mapping technique that translates the extended formal representation into a performance modeling conserving the properties of the formal model. In parallel to the development of a performance model, the formal model can be validated and verified, and their implementation can be tested for conformance towards the original formal model. Finally, the performance modelling is implemented in a programming language, and then simulated. The results from simulation can be reused as inputs for the optimization of the formal specification (functional optimization) or the extended formal model (design optimization). To sum up, the goal of this work is to: Define extensions to current formal methods that allow to enhance the formal specification with performance modeling related information. Develop a method to translate the extended formal specification into a performance modeling. Develop rules and guidelines to automatically implement the performance modeling for the purpose of a performance evaluation (we use the commercial tool Opnet). Develop a consistent and coherent methodology for the integration of performance modeling and formal specification.

Various methods are used to describe communication protocols. The search for suitable description methods for communication protocols in the 1980s yielded a broad range of approaches out of which some fundamental methods have crystallized. These methods constitute the basis of the semantic models of the various formal description techniques. Therefore we first consider the most important description methods in this chapter before we turn to the formal description techniques. From these, finite state machines, Petri nets, process calculi, and temporal logics have crystallized as the most important and most common ones. Apart from these methods, other approaches were also investigated, such as the use of grammars, data flow languages, and functional languages. They did not receive wider attention because they were not applied to real-life protocols. The use of high-level programming languages was considered likewise. Programming languages support the algorithmic description of protocol procedures as well as the generation of prototypes, but they usually do not possess a formally defined semantics. In addition, programming languages are primarily implementation languages and not specification languages. They often yield descriptions which are close to an implementation. For that reason, high-level programming languages are not used for protocol description. Many formal description techniques, however, use programming language features.

Specifications of a simplified transport protocol using different formal description techniques

This paper describes a research result on automatic generation of abstract test cases from INAP protocol in formal specifications by using and applying many existing related algorithms and techniques such as the testing framework, rural Chinese postman tour and UTO (Unique Input Output) sequence concepts. We use the I/OFSM (Input/Output Finite State Machine) generated from SDL specifications and a characterizing sequence, called Unique Input/Output (UIO) sequence, is defined for the I/O FSM. The UIO sequence is combined with the concept of rural Chinese postman tour, without reliable reset capability, to obtain an optimal test sequence. To develop this method, first of all, we establish a framework leading to formal testing methodology which can be used to assess the conformance of an IUT (Implementation Under Test) to the behaviours specified in an I/OFSM which is equivalent to corresponding FDT (Formal Description Technique) specification. By this framework, we present a methodology for automatic test generation from FDT specifications. A prototype of the proposed framework has been built with special attention to real application in order to generate the executable test cases in an automatic way.

We apply formal description techniques (FDT) to model, compose and give operational meaning to the class of reactive systems representing manufacturing enterprises. The enterprise pursues its activities by means of resources and processes that execute concurrently on the resources, subject to internal (resource) and external (market) constraints. Some modelling techniques are familiar for reactive systems, other are specific to this domain: modelling management decisions, product transfer during one-to-one (one supplier one consumer) synchronisation, marketing and many-to-one (many suppliers one consumer) synchronisation. The paper is a novel application of FDTs, also a contribution to the semantics of enterprise engineering.

Protocol conversion is one of the very important research areas in protocol engineering. It is an effective approach to provide interconnectivity and interoperability between two different protocols. A protocol converter is a very complex piece of software, and its design must be precise and complete to provide the expected conversions. Formal description techniques (FDTs), which have formal syntax and semantics, are useful tools for its design. In this paper, we present a survey of existing and widely adopted FDTs, which has been made in view of the requirements of protocol converter design.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Formal description techniques and automated protocol synthesis

: The formal description technique (FDT) Estelle (ISO 9074) was used for the advanced design and development of communication protocols. In particular, two protocols were studied: (1) Partial Order Connection POC (RFC1693), and (2) MIL-STD 188-220: Interoperability Standard for Digital Message Transfer Device Subsystems. POC has been used as the basis of two systems: REMDOR for Remote Multimedia Document Retrieval, and NETCICATS for Network Conscious Image Compression and Transmission. The Estelle specifications of MIL-STD 188-220 were approved as an official component of the MIL-STD in January 1998.

Agents in multiagent systems need to interact in order to exchange information, cooperate or coordinate. This interaction is frequently done through interaction protocols based on distributed system communication protocols. Communication protocols are not directly used due to many differences between agents and objects or processes such as autonomy and interaction [23] [28]. Designers use formal description techniques to represent their protocols. These formal description techniques are either those coming from distributed systems or those specifically tailored to agents. In the last category, Agent UML [24] is certainly one of the most known. This paper presents Agent UML sequence diagrams and addresses several new stereotypes.

This paper presents structuring mechanisms for building executable specifications, in the field of interactive applications, using the Interactive Cooperative Object formal description technique. The design life cycle of the specification is presented as well as how PetShop (a software tool support the ICO formal description technique) can effectively support the various phases of the life cycle. The concepts and the tool are presented on a Range Slider case study. The Range Slider is a medium size component, used for instance, in the field of dynamic queries for information retrieval and visualisation.

In many software application domains, constant evolution is the dominant problem, shaping both software design and the software process. Telecommunication software is the prototypical example of such an application domain. This paper examines how requirements engineering, formal description techniques and formal methods should be adapted to work well in these application domains.

Formal methods in the development of premo

SPIN is a tool to simulate and validate Protocols. PROMELA, its source language, is a formal description technique like SDL and Estelle that is based on communicating state machines. Unlike most other tools, SPIN is in the public domain and therefore is one of the most widely used formal verification tools today.PROMELA allows to specify distributed automata whichcan communicate using either message channels or shared memory. This contribution consists of an extension to SPIN which allows the creation of implementations from PROMELA specifications. This can be used for the creation of test scenarios and the rapid prototyping of validated protocol implementations.

This paper describes the use of the ITU-T specification and description language (SDL) formal description technique to specify the AVPAC avionics protocol, and use of the code-generating abilities of SDL tools to generate source code for an FDAC experiment to provide air-ground radio communications for low-visibility taxi tests at the FAA Technical Center.