Part 1 Basic: introduction protocol structure error control flow control. Part 2 Specification and modeling: validation models correctness requirements protocol design finite state machines. Part 3 Conformance testing synthesis and validation: conformance testing protocol synthesis protocol validation. Part 4 Design tools: a protocol simulator a protocol validator using the validator.

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Design and validation of computer protocols

With advanced computer technology, systems are getting larger to fulfill more complicated tasks: however, they are also becoming less reliable. Consequently, testing is an indispensable part of system design and implementation; yet it has proved to be a formidable task for complex systems. This motivates the study of testing finite stare machines to ensure the correct functioning of systems and to discover aspects of their behavior. A finite state machine contains a finite number of states and produces outputs on state transitions after receiving inputs. Finite state machines are widely used to model systems in diverse areas, including sequential circuits, certain types of programs, and, more recently, communication protocols. In a testing problem we have a machine about which we lack some information; we would like to deduce this information by providing a sequence of inputs to the machine and observing the outputs produced. Because of its practical importance and theoretical interest, the problem of testing finite state machines has been studied in different areas and at various times. The earliest published literature on this topic dates back to the 1950's. Activities in the 1960's mid early 1970's were motivated mainly by automata theory and sequential circuit testing. The area seemed to have mostly died down until a few years ago when the testing problem was resurrected and is now being studied anew due to its applications to conformance testing of communication protocols. While some old problems which had been open for decades were resolved recently, new concepts and more intriguing problems from new applications emerge. We review the fundamental problems in testing finite state machines and techniques for solving these problems, tracing progress in the area from its inception to the present and the stare of the art. In addition, we discuss extensions of finite state machines and some other topics related to testing.

Principles and methods of testing finite state machines-a survey

In combination with a wheel for a bicycle and the like having an annular rim, a hub rotatable about its axis, and axially offset groups of circumferentially spaced spokes which centrally support the hub on the rim; a wheel decorating ornament comprising an annular, planar sheet of material decorated on opposite sides, axially disposed between the groups of spokes and radially disposed between the rim and the hub.

The Test Access Port and Boundary Scan Architecture

Techniques are disclosed for using a combination of explicit and implicit user context modeling techniques to identify and provide appropriate computer actions based on a current context, and to continuously improve the providing of such computer actions. The appropriate computer actions include presentation of appropriate content and functionality. Feedback paths can be used to assist automated machine learning in detecting patterns and generating inferred rules, and improvements from the generated rules can be implemented with or without direct user control. The techniques can be used to enhance software and device functionality, including self-customizing of a model of the user's current context or situation, customizing received themes, predicting appropriate content for presentation or retrieval, self-customizing of software user interfaces, simplifying repetitive tasks or situations, and mentoring of the user to promote desired change.

Contextual responses based on automated learning techniques

A system filters received messages (e.g., unsolicited advertisements) to determine if they are appropriate for a user based on the non-static, constantly evolving, context of the user. The system can track the user's context by monitoring various environmental parameters, such as related to the user's physical, mental, computing and data environments, and can model the current context of the user based at least in part on the monitoring. The system selects a set of one or more filters to apply to incoming messages based on the user's context, and the selected filters can be updated as the user's context changes. Messages that survive the filters are then evaluated against the user's context to determine whether they should be presented immediately or stored for delayed presentation.

Automated selection of appropriate information based on a computer user's context

A Protocol Test Generation Procedure.

The consensus problem is concerned with the agreement on a system status by the fault-free segment of a processor population in spite of the possible inadvertent or even malicious spread of disinformation by the fault segment of that population. The resulting protocols are useful throughout fault-tolerant distributed systems and will impact the design of other decision systems to come. This paper surveys research on the consensus problem, compares approaches, outlines applications, and suggests directions for future work.

The consensus problem in fault-tolerant computing

A method for generating test sequences for checking the conformance of a protocol implementation to its specification is described. A rural Chinese postman tour problem algorithm is used to determine a minimum-cost tour of the transition graph of a finite-state machine. It is shown that, when the unique input/output sequence (UIO) is used in place of the more cumbersome distinguishing sequence, both the controllability and observability problems of the protocol testing problem are addressed, providing an efficient method for computing a test sequence for protocol conformance testing. >

An optimization technique for protocol conformance test generation based on UIO sequences and rural Chinese postman tours

The diagnosability and diagnosis problems for a model introduced by J. Maeng and M. Malek (1981) of a self-diagnosable multiprocessor system where processors compare the results of tasks performed by other processors in the system are analyzed. A set of criteria is given for determining whether the faulty processors in the system can be diagnosed on the basis of the comparisons, and a polynomial-time algorithm is presented to identify the faulty units of such a system on the basis of the comparison results when the system is known to be diagnosable. >

A.T. Dahbura

Papers

A Protocol Test Generation Procedure.

The consensus problem in fault-tolerant computing

An optimization technique for protocol conformance test generation based on UIO sequences and rural Chinese postman tours

An optimization technique for protocol conformance test generation based on UIO sequences and rural Chinese postman tours

On self-diagnosable multiprocessor systems: diagnosis by the comparison approach