The SCPS (Space Communication Protocol Standards) is a suite of protocols proposed as a future standard for spacecraft communication based on the TCP/IP family of protocols. This paper describes a case study in the application of informal and lightweight formal methods to verification of two new features of the SCPS Network Protocol, precedence and flood routing. For each feature, we describe what methods were applied, how they were applied, and what the results were. The use of both informal and formal methods contributed to improvement of the existing specification. Also, some techniques to reduce the state space of the models produced using the SPIN verification tool's language are described.
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.
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.
Drawing on practical engineering experience and latest achievements of space technology in China, this title investigates spacecraft system design and introduces several design methods based on the model development process. A well-established space engineering system with spacecraft as the core is integral to spaceflight activities and missions of entering, exploring, developing and utilizing outer space. This book expounds the key phases in the workflow of spacecraft development, including task analysis, overall plan design, external interface, configuration and assembly design and experimental verification. Subsystems that function as the nuclei of spacecraft design and important aspects in the model development process are then examined, such as orbit design, environmental influence factors, reliability design, dynamics analysis, etc. In addition, it also discusses the digital environment and methods to improve the efficiency of system design. The title will appeal to researchers, students, and especially professionals interested in spacecraft system design and space engineering.
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.
The aim of this book is to bring together the research of academics and practitioners in the field of communication systems testing. It covers four major topic areas; types of testing including conformance testing, inoperability testing, performance and QoS testing; phases of testing including test case generation, means of testing, test execution and test results analysis; classes of systems tested and the theory and practice of testing including test-related algorithms, practical testing methodology and practical testing experience.
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.
