Laprie, J.C. (ed.), Dependability: Basic Concepts and Associated Terminology. Vol. 5, Dependable Computing and Fault-Tolerant Systems Series, Vienna: Springer 1992  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Systems (FTS s) the main objective must be to demonstrate that the behavior of the system conforms to its specifications. This process is an essential prerequisite to know how well the system will tolerate faults; it also quantifies some of the parameters that allow comparisons with other systems [1][4] This work has been partially supported by the ESPRIT Project contract P5212 and by the CICYT contract TAP96 1090 C04 01. This process is not an easy task since it mostly covers aspects related to the overall design, prototyping and test of the analyzed system. Initially, the faulttolerant ....

J. Laprie. " Dependability: basics concepts and associated terminology" . Ed. Springer Verlag, 1992. Dependable Computing and Fault Tolerant Systems Series, number 5.

....measure the reliability of the architecture is to measure the testability. The testability is a function of the effort required in order to assure the required level of reliability or availability. There are three different approaches to handle faults in order to achieve a reliable system [Lapr92]: Fault avoidance . Fault removal . Fault tolerance Fault avoidance is about designing error free systems. This implies the use of structured design methodologies such as formal methods or semi formal methods. Formal methods are based on mathematical models of the software system and the ....

J.C. Laprie, Dependability: Basic Concepts and Associated Terminology, Dependable Computing and Fault-Tolerant Systems, vol. 5, Springer Verlag, 1992

....if we view the program as a state machine, an error (bug) is an unwanted state. We can also view an error as a corrupted data state, caused by the execution of an error (bug) but also due to e.g. physical electromagnetic radiation. A fault is the adjunged (hypothesized) cause for an error [21]. Generally a failure is a fault. but not vice versa, since a fault does not necessarily lead to a failure. Or, in other words: A failure of an entity (system, component, function, etc. is an observed violation to the specification of the entity. A failure is a fault in the output, or product, ....

Jean-Claude Laprie. Dependability: Basic Concepts and Associated Terminology, volume 5 of Dependable Computing and Fault-Tolerant Systems. Springer Verlag, 1992.

....view the program as a state machine, an error (bug) is an unwanted state. We can also view an error as a corrupted data state, caused by the execution of an error (bug) but also due to e.g. physical electromagnetic radiation. Definition. A fault is the adjudged (hypothesized) cause for an error [59]. Generally a failure is a fault, but not vice versa, since a fault does not necessarily lead to a failure. The relation between the definitions of fault, error, and failure, is depicted in Figure 3 3. Systematic and physical failures Failures are usually divided into two categories: ....

.... is essential when performing regression testing or cyclic debugging [92] 96] where the same test cases are run repeatedly with the intent to validate that either an error correction had the desired effect, or simply to make it possible to find the error when a failure has been observed [59], or to show that no new errors have been introduced when correcting another error. However, trying to directly apply test techniques for sequential programs on distributed real time systems is bound to lead to non determinism and non reproducibility, because control is only forced on the inputs, ....

[Article contains additional citation context not shown here]

Laprie J.C. Dependability: Basic Concepts and Associated Terminology. Dependable Computing and Fault-Tolerant Systems, vol. 5, Springer Verlag, 1992.

.... essential when performing regression testing or cyclic debugging, where the same test cases are run repeatedly with the intent to validate that either an TASK Read(X) Write(X) error correction had the desired effect, or simply to make it possible to find the error when a failure has been observed [12]. However, trying to directly apply test techniques for sequential programs on distributed real time systems is bound to lead to non determinism and non reproducibility, because control is only forced on the inputs, disregarding the significance of order and timing of the executing and ....

Laprie J.C. Dependability: Basic Concepts and Associated Terminology. Dependable Computing and Fault-Tolerant Systems, vol. 5, Springer Verlag, 1992.

....but not the expected results of such communication (semantics) Such problems make static veri cation dicult, at best. On the other hand, the structuring of the whole system in terms of the independent, distributed components, is particularly suitable for making such a system fault tolerant [4]. The goal is to ensure that failures of individual components (violation of their speci cations) will not cause the whole system to fail (violation of the system s speci cation) The latter speci cations can be used at design time to prove if the system is indeed fault tolerant. The former ....

J.C. Laprie. Dependability: Basic concepts and associated terminology. Technical report, PDCS, 1990.

....be placed on the service it delivers [6] A service delivered by a system is its behaviour, as it is perceived by its users. A user is another system (human or technical) which interacts with the former. For a more comprehensive introduction to dependability concepts, it is referred to [24] 1 . 2.1 Concepts From an engineering point of view, we are left with the following questions: What causes a system to be less than 100 trustworthy , How should this, less than 100 , trustworthiness be quantied and How should a required trustworthiness be achieved and assessed To ....

....instance [16] Dependability Impairments Means Attributes Faults Errors Failures Procurement Validation Availability Reliability Safety (Security) Fault avoidance Fault tolerance Fault removal Fault forecasting Figure 2. The dependability tree, linking various aspects of dependability [24]. 4 Attributes of a system which describe the properties of a system with respect dependability, and whose quantication determine its dependability. The attributes may be regarded as the following abilities of a system: Availability: to provide a set of services at a given instant ....

Jean-Claude Laprie (Ed), Dependability: Basic Concepts and Associated Terminology, Dependable Computing and Fault Tolerant Systems. Vol-5; Springer, 1992.

....RANDELL FIGURE 2. Failure classification. instruction, instruction sequence or data by an appropriate input pattern) the fault becomes active and produces an error; if and when the erroneous data affect the delivered service (in value and or in timing of their delivery) a failure occurs. [14] The recognition of the importance of this chain, which takes the form of . event cause state event cause . led to a great increase in our ability to understand, and to design means of ameliorating, all sorts of complex manifestations of undependability. Let me give ....

Laprie, J. C. (ed.) (1991) Dependability: basic concepts and associated terminology. In Dependable Computing and FaultTolerant Systems. Springer-Verlag, Berlin.

....sets the corresponding bit of the CSR register to enable bus mastership. 5. 7 Evaluation of the dependability of the DPU Demonstrator 3 One of the most important aspects to consider in the design of a general purpose fault tolerant computer is the evaluation of the dependability of the system [Laprie 90] The main objective must be to demonstrate that the behaviour of the system conforms to its specifications. This process is an essential prerequisite to knowing how well the system will tolerate faults; it also quantifies some parameters that allow comparisons to be made with other systems. Any ....

LAPRIE, J. Dependability: Basic Concepts and Associated Terminology. Internal Report No.90055, Laboratoire d'Automatique et d'Analyse des Systemes, Toulouse, France, March 1990.

....according to their required behavior. Here the components are not given in a form allowing us to analyze such assumptions but only to detect and hopefully recover from their incorrect behavior at run time. This is the domain of fault tolerance: building reliable software from unreliable components [8]. The goal is not to remove all faults before the system is put into practice but to prevent failures of individual components from causing a failure of the whole system. This emphasizes the dual use of a specification, on the one hand expressing the assumption for a correct behavior of a ....

.... should achieve and how the information about violation of the specification is made available to the environment, goes beyond on line, specification based testing [13] In this sense the work presented here is more related to fault tolerance: building reliable systems from unreliable components [8]. The formal model in RAISE [12] together with formal justification of the correctness of the wrapper generator (that every wrapped component is fail stop) will be the subject of a companion paper. We plan to continue this work in several directions. One is to further investigate theoretical ....

J.C. Laprie. Dependability: Basic concepts and associated terminology. Technical report, PDCS, 1990.

....in section 7 after we validate this initial model. 4 Validation Validation is a check of the abstract specification against what is required of the system. Performing a validation will initially ensure that we build the right system, as opposed to verification that we build the system right [8]. This is an initial step at ensuring correctness of the specification. We only need to verify that a specification implements the abstract one to ensure that it preserves the properties required. For our system, such properties include: ffl Attempting to dial an invalid number, a subscriber will ....

J.C. Laprie. Dependability: Basic Concepts and Associated Terminology. Technical report, PDCS, 1990.

....as a result. The scope of this section is to define some basic terms that are used throughout this document. The vocabulary is intended to be consistent with engineering terminology and may conflict with some computer science definitions[Tan95] Neu95,p. 12] The definitions are extracts from [Lev95,Lap92] and are compliant with the standard IEC1508. 3.1 Definitions Definition. Reliability is the probability that a piece of equipment or component will perform its intended function satisfactorily for a prescribed time and under stipulated environmental conditions [Lev95] Reliability is often ....

....The computer can however fail, either due to failures in the hardware or due to errors (bugs) in the design (program) when it is executed. Fault Error FailureFailure Fault Figure 2. Cause consequence diagram of fault, error and failure. 9 Definition. A fault is the adjugated cause for an error [Lap92]. Generally a failure is a fault, but not vice versa, since a fault does not necessarily lead to a failure. A distinction can be made between primary faults, secondary faults and command faults [Lev95,pp. 173] Primary faults (and failures) A primary fault (failure) is caused by an error in ....

[Article contains additional citation context not shown here]

J.C. Laprie. "Dependability: Basic Concepts and Associated Terminology" in Dependable Computing and Fault-Tolerant Systems, vol. 5, Springer Verlag, 1992.

.... is essential when performing regression testing or cyclic debugging [53] 56] where the same test cases are run repeatedly with the intent to validate that either an error correction had the desired effect, or simply to make it possible to find the error when a failure has been observed [33], or to show that no new errors have been introduced when correcting another error. However, trying to directly apply test techniques for sequential programs on distributed real time systems is bound to lead to non determinism and non reproducibility, because control is only forced on the inputs, ....

....view the program as a state machine, an error (bug) is an unwanted state. We can also view an error as a corrupted data state, caused by the execution of an error (bug) but also due to e.g. physical electromagnetic radiation. Definition. A fault is the adjudged (hypothesized) cause for an error [33]. Generally a failure is a fault, but not vice versa, since a fault does not necessarily lead to a failure. The relation between the definitions of fault, error, and failure, is depicted in Figure 3 1. Fault Error FailureFailure Fault Figure 3 1. Cause consequence diagram of fault, error and ....

Laprie J.C. Dependability: Basic Concepts and Associated Terminology. Dependable Computing and Fault-Tolerant Systems, vol. 5, Springer Verlag, 1992.

....Nina T. Bhatti, Matti A. Hiltunen, and Richard D. Schlichting Department of Computer Science The University of Arizona Tucson, Arizona 85721 Introduction Computer system dependability that is, the basic trustworthiness of a computer system that allows people to rely on the service it delivers [Lapr92] is an increasingly important issue. Not only are computers becoming more pervasive, they are also being used in critical applications where failures resulting in deviation from specified service can have disastrous consequences. For example, air traffic control, banking, and nuclear reactor ....

Laprie, J.C. (ed.) Dependability: Basic Concepts and Associated Terminology. Vol. 5, Dependable Computing and Fault-Tolerant Systems Series, Springer-Verlag, Vienna, 1992.

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Laprie, J.C. (ed.), Dependability: Basic Concepts and Associated Terminology. Vol. 5, Dependable Computing and Fault-Tolerant Systems Series, Vienna: Springer 1992

No context found.

J.C. Laprie, (Ed.). Dependability: Basic Concepts and Associated Terminology, Dependable Computing and Fault-Tolerant Systems. Springer-Verlag, 1991. [(Contributors: T. Anderson, A. Avizienis, W.C. Carter, A. Costes, F. Cristian, Y. Koga, H. Kopetz, J.H. Lala, J.C. Laprie, J.F. Meyer, B. Randell, A.S. Robinson, L. Simoncini, U. Voges.)]

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J.C. Laprie. Dependability: Basic concepts and associated terminology. In Dependable Computing and Fault-Tolerant System, volume 5. Springer Verlag, 1992.

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