During the last decade, different methods were developed to produce optimized test sequences for detecting faults in, communication protocol implementations. However, the application of these methods gives only limited information about the location of detected faults. We propose a complementary step, which localizes the faults, once detected. It consists of a generalized diagnostic algorithm for the case where more than one fault may be present in the transitions of a system represented by communicating nondeterministic finite state machines, if existing faults are detected, this algorithm permits the generation of a minimal set of diagnoses, each of which is formed by a set of transitions suspected of being faulty. A simple example is used to demonstrate the functioning of the proposed diagnostic algorithm. The complexity of each step in the algorithm are calculated.

Systematic test sequence generation for conformance testing of communication protocol implementations, has been an active research area during the last decade. Methods were developed to produce optimized test sequences for detecting faults in such systems. However the application of these methods gives only limited information about the location of detected faults. In this paper we propose a complementary step, which localizes the fault, once detected. It consists of a generalized diagnostic algorithm for the case where distributed system specifications (implementations) are given in the form of communicating nondeterministic finite state machines. Such algorithm localizes the faulty transition once the fault has been detected. The algorithm guarantees the correct diagnosis of any single (output and/or transfer) fault. A simple example is used to demonstrate the functioning of the proposed algorithm. The complexity of each step in the algorithm and hence, the overall complexity are calculated.

It is well known that the tests and diagnostics influence greatly communication software reliability. The testability and the easiness of the diagnostic process of communication software are becoming major concerns of the design community. The fault detection and the fault localization problems are strongly related issues. The ease of diagnostics can be seen as a criterion of testability; it is in fact characterized by specific requirements at the design level. We make a clear link between these two issues and we study the influence of some testability factors on the diagnostic activity. We present our results and hints on "diagnosability" in the context of a finite state machine model.

The authors propose a generalized diagnostic algorithm for the case where more than one fault (output or transfer) may be present in one of the transitions of a deterministic system represented by a set of communicating finite state machines (CFSMs). Such an algorithm localizes the faulty transition in the distributed system once the fault has been detected. It generates, if necessary, additional diagnostic test cases which depend on the observed symptoms and which permit the location of the detected faults. The algorithm guarantees the correct diagnosis of any single or double fault (output and/or transfer) in at most one of the transitions of a deterministic system which is represented by a set of communicating FSMs. A simple example is used to demonstrate the functioning of the different steps of the proposed diagnostic algorithm.>

The authors propose a generalized diagnostic algorithm for the case where more than one fault (output and/or transfer) may be present in the transitions of a system represented by a deterministic finite state machine (FSM). If existing faults are detected, this algorithm permits the generation of a minimal set of diagnoses, each of which is formed by a set of transitions (with specific types of faults) suspected of being faulty. The occurrence in an implementation of all the faults of a given diagnosis allows the explanation of all observed implementation outputs. The algorithm guarantees the correct diagnosis of certain configurations of faults (output and/or transfer) in an implementation, which are characterized by a certain type of independence of the different faults. The authors also propose an approach for selecting additional test cases, which allows the reduction of the number of possible diagnoses. A simple example is used to demonstrate the different steps of the algorithm.>

An algorithm that localizes the faulty transition in a deterministic finite state machine (FSM) once the fault has been detected is presented. The diagnostic algorithm generates, if necessary, additional diagnostic test cases which depend on the observed symptom and which permit the location of the detected fault. The algorithm guarantees the diagnosis of any single fault in an FSM. An application example, explaining the functioning of the algorithm, is provided.>

A method for the selection of appropriate test case, an important issue for conformance testing of protocol implementations as well as software engineering, is presented. Called the partial W-method, it is shown to have general applicability, full fault-detection power, and yields shorter test suites than the W-method. Various other issues that have an impact on the selection of a suitable test suite including the consideration of interaction parameters, various test architectures for protocol testing and the fact that many specifications do not satisfy the assumptions made by most test selection methods (such as complete definition, a correctly implemented reset function, a limited number of states in the implementation, and determinism), are discussed.>