This volume presents the latest research worldwide on communications protocols, emphasizing specification and compliance testing. It presents the complete proceedings of the fifteenth meeting on `Protocol Specification, Testing and Verification' arranged by the International Federation for Information Processing.

This PSTV'94 Symposium is the fourteenth of a series of annual meetings organized under the auspices of IFIP W.G. 6.1, a Working Group dedicated to "Architectures and Protocols for Computer Networks". This is the oldest and most established symposium in the emerging field of protocol engineering which has spawn many international conferences including FORTE (International Conference on Formal Description Tech niques), IWPTS (International Workshop on Protocol Test Systems), ICNP (Interna tional Conference on Network Protocols) and CAY (Conference on Computer-Aided Verification). The main objective of this PSTV symposium is to provide a forum for researchers and practitioners in industry and academia interested in advances in using formal methods and methodologies to specify, develop, test and verify communication protocols and distributed systems. This year's PSTV symposium enjoys a nice mixture of formal methods and practical issues in network protocols through the invited addresses of three outstanding speakers, Ed Brinksma (University of Twente), Raj Jain (Ohio State University) and David Tennenhouse (MIT) as well as 5 tutorials, in addition to 9 techni cal sessions and two practical panel sessions. The 5 tutorials are offered on the first day in two parallel tracks for intensive exposure on hot topics of current interest. This year, out of 51 submissions the Program Committee selected 18 regular papers (with an allotment of 16 pages in the Proceedings) and 9 mini-papers (of 8 pages).

For more than a decade, researchers and engineers have been addressing the problem of the application of formal description techniques to protocol specification, implementation, testing and verification. This book identifies the many successes that have been achieved within the industrial framework and the difficulties encountered in applying theoretical methods to practical situations. Issues discussed include: testing and certification; verification; validation; environments and automated tools; formal specifications; protocol conversion; implementation; specification languages and models. Consideration is also given to the concerns surrounding education available to students and the need to upgrade and develop this through sponsorship of a study of an appropriate curriculum at both undergraduate and graduate levels. It is hoped this publication will stimulate such support and inspire further research in this important arena.

Formal Description Techniques and Protocol Specification, Testing and Verification addresses formal description techniques (FDTs) applicable to distributed systems and communication protocols. It aims to present the state of the art in theory, application, tools and industrialization of FDTs. Among the important features presented are: FDT-based system and protocol engineering; FDT-application to distributed systems; Protocol engineering; Practical experience and case studies. Formal Description Techniques and Protocol Specification, Testing and Verification comprises the proceedings of the Joint International Conference on Formal Description Techniques for Distributed Systems and Communication Protocols and Protocol Specification, Testing and Verification, sponsored by the International Federation for Information Processing, held in November 1998, Paris, France. Formal Description Techniques and Protocol Specification, Testing and Verification is suitable as a secondary text for a graduate-level course on Distributed Systems or Communications, and as a reference for researchers and practitioners in industry.

FORTE/PSTV '97 addresses Formal Description Techniques (FDTs) applicable to Distributed Systems and Communication Protocols (such as Estelle, LOTOS, SDL, ASN.1, TTCN, Z, Automata, Process Algebra, Logic). The conference is a forum for presentation of the state-of-the-art in theory, application, tools and industrialization of FDTs, and provides an excellent orientation for newcomers.

Communication protocols are rules whereby meaningful communication can be exchanged between different communicating entities. In general, they are complex and difficult to design and implement. Specifications of communication protocols written in a natural language (e.g. English) can be unclear or ambiguous, and may be subject to different interpretations. As a result, independent implementations of the same protocol may be incompatible. In addition, the complexity of protocols make them very hard to analyze in an informal way. There is, therefore, a need for precise and unambiguous specification using some formal languages. Many protocol implementations used in the field have almost suffered from failures, such as deadlocks. When the conditions in which the protocols work correctly have been changed, there has been no general method available for determining how they will work under the new conditions. It is necessary for protocol designers to have techniques and tools to detect errors in the early phase of design, because the later in the process that a fault is discovered, the greater the cost of rectifying it. Protocol verification is a process of checking whether the interactions of protocol entities, according to the protocol specification, do indeed satisfy certain properties or conditions which may be either general (e.g., absence of deadlock) or specific to the particular protocol system directly derived from the specification. In the 80s, an ISO (International Organization for Standardization) working group began a programme of work to develop formal languages which were suitable for Open Systems Interconnection (OSI). This group called such languages Formal Description Techniques (FDTs). Some of the objectives of ISO in developing FDTs were: enabling unambiguous, clear and precise descriptions of OSI protocol standards to be written, and allowing such specifications to be verified for correctness. There are two FDTs standardized by ISO: LOTOS and Estelle. Communication Protocol Specification and Verification is written to address the two issues discussed above: the needs to specify a protocol using an FDT and to verify its correctness in order to uncover specification errors in the early stage of a protocol development process. The readership primarily consists of advanced undergraduate students, postgraduate students, communication software developers, telecommunication engineers, EDP managers, researchers and software engineers. It is intended as an advanced undergraduate or postgraduate textbook, and a reference for communication protocol professionals.

The increasing number of computer networks has aroused users' interest in many and various fields of applications, in how a computer network can be built, and in how it may be used. The fundamental rules of computer networks are the protocols. "A protocol is a set of rules that governs the operation of functional units to achieve communication" [STA-86}. The book follows a practical approach to protocol speci fication and testing, but at the same time it introduces clearly and precisely the relevant theoretical fundamentals. The principal objectives of this work are: to familiarize readers with communication protocols, to present the main, formal description techniques, to apply various formal description techniques to protocol specification and testing. It is considered that the readership will primarily consist of protocol developers, protocol users, and all who utilize protocol testers. Secondly the book is suggested for postgraduate courses or other university courses dealing with communication networks and data communication. A large part of the book provides a comprehensive overview for managers; some parts are of especial interest to postal organizations. The book consists of three parts: the first part introduces the OS! Reference Model, it provides an overview of the most frequently used protocols and explains the fundamentals of protocol testing. The second part familiarizes readers with the methods used for protocol 5pecification, generation, and testing. Finite-state machines, formal grammars, Petri nets and some speCification languages (SDL, ESTELLE, LOTOS) are discussed in a pragmatic style. The third part deals with applications.