Improvements on handling design errors in communication protocols.

With the rapid development of the Internet and distributed systems, communication protocols play a more and more important role. The correctness of the design of these communication protocols becomes crucial especially when critical applications are concerned. Common logical design errors in communication protocols include deadlock states, unspecified receptions, channel overflow, non-executable transitions, etc. Such design errors can be removed via protocol synthesis, or be detected through reachability analysis. The former may introduce more states and transitions than needed and the latter suffers from state space explosion problem. Here we present an improvement on existing technique to transform a protocol design into a deadlock-free one where the number of introduced new states and transitions can be considerably reduced. We also propose a sound reduction technique on a class of protocol designs to significantly reduce their sizes in order to perform reachability analysis.Dept. of Computer Science. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .D83. Source: Masters Abstracts International, Volume: 44-03, page: 1399. Thesis (M.Sc.)--University of Windsor (Canada), 2005

Verification of Modular Systems with Unknown Components Combining Testing and Inference

26 pagesVerification of a modular system composed of communicating components is a difficult problem, especially when the formal specifications, i.e., models of the components are not available. Conventional testing techniques are not efficient in detecting erroneous interactions of components because interleavings of internal events are difficult to reproduce in a modular system. The problem of detecting intermittent errors and other compositional problems in the absence of components' models is addressed in this paper. A method to infer a controllable approximation of communicating components through testing is elaborated. The inferred finite state models of components are used to detect compositional problems in the system through reachability analysis. To confirm a flaw in a particular component, a witness trace is used to construct a test applied to the component in isolation. The models are refined at each analysis step thus making the approach iterative

A specification of a CSMA/CD protocol using systems of communicating machines.

This thesis gives a specification of a communication protocol known as "Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Medium Access Control and Physical Layer Specifications" using Systems of Communicating Machines and shared variables. This protocol is defined in the ANSI/IEEE Standard 802.3 (using the same name). Specification has been analysed using a method called system state analysis. The analysis showed the protocol to be free from deadlocks. The study concludes that CSMA/CD protocol needs a better specification method.http://archive.org/details/specificationofc00lofcLieutenant Junior Grade, Turkish NavyApproved for public release; distribution is unlimited

Dynamic Protocol Reverse Engineering a Grammatical Inference Approach

Round trip engineering of software from source code and reverse engineering of software from binary files have both been extensively studied and the state-of-practice have documented tools and techniques. Forward engineering of protocols has also been extensively studied and there are firmly established techniques for generating correct protocols. While observation of protocol behavior for performance testing has been studied and techniques established, reverse engineering of protocol control flow from observations of protocol behavior has not received the same level of attention. State-of-practice in reverse engineering the control flow of computer network protocols is comprised of mostly ad hoc approaches. We examine state-of-practice tools and techniques used in three open source projects: Pidgin, Samba, and rdesktop . We examine techniques proposed by computational learning researchers for grammatical inference. We propose to extend the state-of-art by inferring protocol control flow using grammatical inference inspired techniques to reverse engineer automata representations from captured data flows. We present evidence that grammatical inference is applicable to the problem domain under consideration

A Petri net-occam based methodology for the development of dependable distributed control software.

Analysis of flexible manufacturing cells (FMCs) shows their requirement for flexible, correct, reliable, safe and distributed control. A comparison of the state of the art in software engineering for parallel systems, and an examination of safety related systems, reveal a need for formal and rigorous techniques at all stages in the software life cycle. However, parallel software, safety related software and formal techniques are complex. It is better to avoid faults rather than eliminate or tolerate them, and although less flexible, avoidance is often simpler to implement. There is a need for a tool which overcomes many of these complexities, and this thesis discusses and defines such a tool in the form of a methodology. The novelty of the work is in the combination of the core goals to manage these issues, and how the strategies guide the user to a solution which will not deadlock and which is comprehensible. Place-transition Petri nets are an ideal representation for designing and modelling the interaction of concurrent (and distributed) processes. Occam is a high level real time parallel language designed to execute on one or a network of transputers. Transputers are processing, memory and communication building blocks, and, together with occam, are shown to be suitable for controlling and communicating the control as the DCS in FMCs. The methodology developed in this thesis adopts the mathematically based tools of Petri nets, occam and transputers, and, by exploiting their structural similarities, incorporates them in a steps and tasks to improve the development of correct, reliable and hence safe occam code. The four steps: identify concurrent and sequential operations, produce Petri net graphs for all controllers, combine controller Petri net graphs and translate Petri net graphs into occam; are structured around three core goals: Petri net/occam equivalence, comprehensibility and pro-activity; which are manifest in four strategies: output-work-backwards, concurrent and sequential actions, structuralise and modularise, and deadlock avoidance. The methodology assists in all stages of the software development life cycle, and is applicable to small DCSs such as an FMC. The methodology begins by assisting in the creation of DCS requirements from the manufacturing requirements of the FMC, and guides the user to the production of dependable occam code. Petri nets allow the requirements to be specified as they are created, and the methodology's imposed restrictions enable the final Petri net design to be translated directly into occam. Thus the mathematics behind the formal tools is hidden from the user, which should be attractive to industry.The methodology is successfully applied to the example FMC, and occam code to simulate the FMC is produced. Due to the novelty of the research, many suggestions for further work are given

The Oracle Problem in Software Testing: A Survey

Testing involves examining the behaviour of a system in order to discover potential faults. Given an input for a system, the challenge of distinguishing the corresponding desired, correct behaviour from potentially incorrect behavior is called the “test oracle problem”. Test oracle automation is important to remove a current bottleneck that inhibits greater overall test automation. Without test oracle automation, the human has to determine whether observed behaviour is correct. The literature on test oracles has introduced techniques for oracle automation, including modelling, specifications, contract-driven development and metamorphic testing. When none of these is completely adequate, the final source of test oracle information remains the human, who may be aware of informal specifications, expectations, norms and domain specific information that provide informal oracle guidance. All forms of test oracles, even the humble human, involve challenges of reducing cost and increasing benefit. This paper provides a comprehensive survey of current approaches to the test oracle problem and an analysis of trends in this important area of software testing research and practice