J.-C. Laprie. "Dependable Computing: Concepts, Limits, Challenges". Special Issue of the 25th International Symposium On Fault-Tolerant Computing. IEEE Computer Society Press. Pasadena, CA. June 1995. pp. 42-54  Home/Search   Document Not in Database   Summary   Related Articles   Check

....attention to dependability. Dependability is defined as that property of a computer based system that enables reliance to be placed on the service it delivers. That service is its behavior as perceived by other systems or its human users [1] Figure 1 [1] 2] an update on earlier work [3][4]) depicts the concepts of dependability in terms of threats to, attributes of, and the means by which, dependability is attained. The effectiveness of these four mechanisms has a substantial influence on the dependability of a computerbased system. Figure 1 The Dependability Tree Randell ....

....billions of networked information devices . Although currently the research emphasis for making this a reality is on usability, dependability will increasingly become an issue [1] with a critical role for Autonomic Computing. 4. Autonomic Computing and Dependability Randell and colleagues [2] [4] give two main reasons for their interest in and focus on the concepts and definitions of dependability, failures, errors, faults and tolerance. First, there is a need to clarify the subtleties involved. Secondly, and possibly more important, is a desire to avoid dependability concepts being ....

J.C. Laprie, "Dependable computing: concepts, limits, challenges". In Proceedings 25 IEEE International Symposium on Fault-Tolerant Computing --Special Issue, Pasadena, CA, pp42-54, 1995.

....The dependability of these critical information systems has become a major concern [12, 13] Dependability is a system property that is usually stated as a set of requirements with which the system has to comply. Dependability has many facets reliability, availability, safety, and so on [7] and to permit exact requirements statements about systems, each of these terms has a precise meaning. For example, the reliability of a system, R(t) is defined to be the probability that the system will meet its requirements up until time t when operating in a prescribed environment. ....

....fault tolerance. Fault tolerance is a mechanism that can be used to achieve certain dependability properties. In terms of dependability, it makes sense to refer to a system as reliable, available, secure, safe, survivable and so on, or some combination using the appropriate formal definition(s) [7]. Describing a system as fault tolerant is really a statement about the system s design, not its dependability. While fault tolerance is a mechanism by which some facets of dependability might be achieved, it is not the only mechanism. Other techniques, such as fault avoidance, can be used also. ....

Laprie, J. "Dependable Computing: Concepts, Limits, Challenges," Special Issue FTCS-25: 25th International Symposium on Fault-Tolerant Computing, June 1995, pp. 42-54.

....attribute of all computing systems. However, the necessary level of dependability varies from system to system. Whatever the required level, users need confidence that it is provided by the system. The validation of the system, via both verification and evaluation, can provide that confidence [1]. Evaluation of a fault tolerant system involves the determination of the efficiency of its fault tolerant mechanisms in covering the faults and errors (the activation of a fault) for which they were designed. Before one can properly evaluate a system, a thorough understanding of those mechanisms ....

J.-C. Laprie, "Dependable computing: Concepts, limits, challenges," in Proceedings of the 25 International Symposium on Fault-Tolerant Computing, Special Issue, 1995, pp. 42-54.

....although the level of dependability required varies from system to system. In order to ensure that a given computer system has the level of dependability required, the system must be carefully validated. This validation procedure is a combination of system verification and system evaluation [1]. Verification is the process of determining, through methods such as testing or formal proofs, whether a system meets its functional specification. Evaluation is the process of determining how well a system meets its performance and dependability requirements once it meets its functional design ....

....determined by the holding time of the global state and the time to transmit a notification after the state is reached. Any fault injection based on a global state of the system must be checked after the experiment is completed. More details regarding this checking are covered in Section 2. 4 and in [1]. 8 Loki also does not employ any on line clock synchronization algorithms since on line clock synchronization is expensive and intrusive. Additionally, on line clock synchronization is unnecessary, since faults that are based on a global time can be triggered by a combination of the partial ....

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J. --C. Laprie, "Dependable computing: Concepts, limits, challenges," in Proceedings of the 25 International Symposium on Fault-Tolerant Computing, Special Issue,

....these critical information systems has therefore become a major concern [5, 6] Dependability is a property that a system might have and is usually stated as a set of requirements with which the system has to comply. Dependability has many aspects reliability, availability and safety, and so on [4] and to permit precise requirements statements about systems, each of these terms has a precise meaning. For example, the reliability of a system, R(t) is defined to be the probability that the system will meet its requirements up until time t when operating in a prescribed environment. ....

....property. Fault tolerance is a mechanism that can be used to achieve certain dependability properties. In terms of dependability, it only makes sense to refer to a system as reliable, available, secure, safe, survivable and so on, or some combination using the appropriate formal definition(s) [4]. Fault tolerance is a mechanism by which some aspect of dependability might be achieved but it is not the only mechanism. Fault avoidance can be used also. Thus, for example, by careful component selection it might be possible to reduce the rate of hardware failures in a given system to a ....

Laprie, J. "Dependable Computing: Concepts, Limits, Challenges," Special Issue FTCS-25: 25th International Symposium on Fault-Tolerant Computing, June 1995, pp. 42-54.

....software metrics, fault injection 1. Introduction As software based functionality becomes pervasive in embedded control systems, software usually comprises numerous discrete software modules interacting with each other in order to provide a specific task or service. When errors (as defined in [Laprie95]) are present in one software module, there is a likelihood that this error can propagate to other software modules with which it interacts. Knowing where errors propagate in a system is of particular importance for a number of development activities. Propagation analysis may be used to find the ....

Laprie J.-C., "Dependable Computing: Concepts, Limits, Challenges", Special Issue, 25 th Int. Symp. on FaultTolerant Comp., pp. 42-54, 1995.

.... the faulty behavior of a software executive The confidence one can have on the microkernel is related to the impact of its failure on the upper layers, i.e. the consequence of a fault within the microkernel to propagate through its interface (according to the causal chain fault error failure [Laprie 1995]) The origin can be physical or due to design or implementation faults. In the sequel, we successively discuss several issues involved in the analysis of the faulty behavior of a software executive. These include: the identification of the various fault injection means suitable to investigate ....

J.-C. Laprie, "Dependable Computing: Concepts, Limits, Challenges", in Proc. 25th IEEE Int. Symp. on Fault-Tolerant Computing (FTCS-25). Special Issue, (Pasadena, CA, USA), pp.42-54, 1995.

....set of observations to be made to check the service or fault tolerance predicates in order to assess the coverage of the testing criteria actually achieved. 2. 2 Modelling Fault Tolerance Fault tolerance embodies methods and techniques enabling a system to fulfill its function in spite of faults [13]. Fault tolerance is carried out by error processing and by fault treatment. Error processing is aimed at removing errors from the computational state, if possible before failure occurrence; fault treatment is aimed at preventing faults from being activated again. Fault tolerance is based on two ....

J.-C. Laprie, "Dependable Computing: Concepts, Limits, Challenges", in Proc. 25th Int. Symp. on Fault-Tolerant Computing (FTCS-25). Special Issue, Pasadena, CA, USA, 1995, pp. 42-54 (IEEE Computer Society Press).

....of the MAFTIA conceptual model and a discussion of the MAFTIA architecture. It also introduces the work done in WP6 on verification and assessment of security properties, which is reported on in more detail in MAFTIA deliverable D4 [Adelsbach Pfitzmann 2001] Chapter 2 is taken largely from [Laprie et al. 1995] and presents core dependability concepts. Chapter 3 refines these in the context of malicious faults, and examines the distinction between intrusions, attacks, and vulnerabilities. There is also a discussion of how the traditional methods of building dependable systems, namely fault prevention, ....

....and directions for future work, and an appendix contains a glossary of the terms used in the deliverable. Conceptual Model and Architecture 3 Chapter 2 Core dependability concepts The purpose of this chapter is to recall some core dependability concepts, extracted mostly literatim from [Laprie et al. 1995, chapter 1] 1 . We then extend and refine these definitions in the context of security and intrusion tolerance detection. Readers familiar with the core dependability concepts may proceed directly to Chapter 3. 2.1 Basic definitions Dependability is that property of a computer system such ....

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J.-C. Laprie, "Dependable Computing: Concepts, Limits, Challenges", in Special Issue, 25th IEEE Int. Symp. on Fault-Tolerant Computing (FTCS-25), (Pasadena, CA, USA), pp.4254, IEEE Computer Society Press, 1995.

....when the delivered service deviates from implementing the system function, that is, from what the system is intended for. An error is that part of the system state that may lead to a failure: an error affecting the 3 The most recent readily available version of these concepts may be found in [Laprie 1995]. Malicious and Accidental Fault Tolerance for Internet Applications 31 service is an indication of a failure occurring or which has occurred. The adjudged or hypothesised cause of an error is a fault. Development of a dependable system requires the combined use of a set of methods that can ....

.... of the situations to which a system is submitted during its validation compared to the actual situations it will be confronted with during its operational life [Laprie 1992] dependability: property of a computer system such that reliance can be justifiably placed on the service it delivers [Laprie 1995]. dependence: the state of being dependent on other support [OMED 1992] reliance, trust, confidence [OMED 1992] dependent: depending, conditional or subordinate [OMED 1992] effort = an expense (of bodily or mental energy) to achieve a desired end [LMED 1976] error: part of the state of ....

J.-C. Laprie, "Dependable Computing: Concepts, Limits, Challenges", in Special Issue, 25th IEEE Int. Symp. on Fault-Tolerant Computing (FTCS25) , (Pasadena, CA, USA), pp.42-54, IEEE Computer Society Press, 1995.

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J.-C. Laprie. "Dependable Computing: Concepts, Limits, Challenges". Special Issue of the 25th International Symposium On Fault-Tolerant Computing. IEEE Computer Society Press. Pasadena, CA. June 1995. pp. 42-54

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Laprie J.-C., "Dependable Computing: Concepts, Limits, Challenges ", Proc. FTCS-25, pp. 42-54, 1995.

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J.-C. Laprie. "Dependable Computing: Concepts, Limits, Challenges". Special Issue of the 25th International Symposium On Fault-Tolerant Computing. IEEE Computer Society Press. Pasadena, CA. June 1995. pp. 42-54

No context found.

Laprie J.-C., "Dependable Computing: Concepts, Limits, Challenges ", Proc. FTCS-25, pp. 42-54, 1995.

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