In this paper, we consider a new atomicity model, write all with collision (WAC), and compare it with existing models considered in the literature. This model captures the computations in sensor networks. We show that...
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Modern object-oriented programs are hierarchical systems with many thousands of interrelated subsystems. Visualization helps developers to better comprehend these large and complex systems. This paper presents a three...
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Many developers who could benefit from building and analysing formal models of their systems are deterred from doing so by the process algebra style input languages of formal modelling languages which they find diffic...
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Peer-to-Peer (P2P) computing is said to be the next wave of computing after client-server and web-based computing. It provides an opportunity to harness a lot of idle peer-resources such as desktop computers across th...
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This paper describes an online control framework to design self-managing distributed computing systems that continually optimize their performance in response to changing computing demands and environmental conditions...
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ISBN:
(纸本)1581139896
This paper describes an online control framework to design self-managing distributed computing systems that continually optimize their performance in response to changing computing demands and environmental conditions. An on-line control technique is used in conjunction with predictive filters to tune the performance of individual system components based on their forecast behavior. In a distributed setting, a global controller is used to manage the interaction between components such that overall system requirements are satisfied.
Predicate abstraction is a major method for verification of software. However, the generation of the abstract Boolean program from the set of predicates and the original program suffers from an exponential number of t...
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Predicate abstraction is a major method for verification of software. However, the generation of the abstract Boolean program from the set of predicates and the original program suffers from an exponential number of theorem prover calls as well as from soundness issues. This paper presents a novel technique that uses an efficient SAT solver for generating the abstract transition relations of ANSI-C programs. The SAT-based approach computes a more precise and safe abstraction compared to existing predicate abstraction techniques.
This paper describes TRAP/J, a software tool that enables new adaptable behavior to be added to existing Java applications transparently (that is, without modifying the application source code and without extending th...
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The object constraint language (OCL) was introduced as part of the Unified Modeling Language (UML). Its main purpose is to make UML models more precise by providing a constraint language. For example, operation contra...
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The object constraint language (OCL) was introduced as part of the Unified Modeling Language (UML). Its main purpose is to make UML models more precise by providing a constraint language. For example, operation contracts and statechart guard conditions can be precisely defined using OCL. There has been an ongoing debate on the usefulness of using OCL in UML-based development, questioning whether the additional effort and formality were worth the benefit. This work presents the results of a controlled experiment that investigates the impact of using OCL on model comprehension and maintainability. Current results show that, once past an initial learning curve, significant benefits can be obtained by using OCL in combination with UML diagrams.
Many developers who could benefit from building and analysing formal models of their systems are deterred from doing so by the process algebra style input languages of formal modelling languages which they find diffic...
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Many developers who could benefit from building and analysing formal models of their systems are deterred from doing so by the process algebra style input languages of formal modelling languages which they find difficult to read and understand. This barrier to the adoption of formal modelling techniques can be significantly reduced if the process algebra is replaced with a graphical notation supported by a model generation tool. However, whilst having a diagrammatic base for the language appeals to the novice modeller, the diagrams can become cluttered for larger models. In this paper we address the issues of how to add hierarchical features to a graphical language without losing the fundamental benefits and appeal of having the graphical interface to the language. We illustrate these ideas using an existing formal modelling language
We concentrate on automated synthesis of multitolerant programs, i.e., programs that tolerate multiple classes of faults and provide a (possibly) different level of fault-tolerance to each class. We consider three lev...
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We concentrate on automated synthesis of multitolerant programs, i.e., programs that tolerate multiple classes of faults and provide a (possibly) different level of fault-tolerance to each class. We consider three levels of fault-tolerance: (1) failsafe, where in the presence of faults, the synthesized program guarantees safety, (2) nonmasking, where in the presence of faults, the synthesized program recovers to states from where its safety and liveness are satisfied, and (3) masking where in the presence of faults the synthesized program satisfies safety and recovers to states from where its safety and liveness are satisfied. We focus on the automated synthesis of finite-state multitolerant programs in high atomicity model where the program can read and write all its variables in an atomic step. We show that if one needs to add failsafe (respectively, nonmasking) fault-tolerance to one class of faults and masking fault-tolerance to another class of faults then such addition can be done in polynomial time in the state space of the fault-intolerant program. However, if one needs to add failsafe fault-tolerance to one class of faults and nonmasking fault-tolerance to another class of faults then the resulting problem is NP-complete. We find this result to be counterintuitive since adding failsafe and nonmasking fault-tolerance to the same class of faults (which is equivalent to adding masking fault-tolerance to that class of faults) can be done in polynomial time, whereas adding failsafe fault-tolerance to one class of faults and nonmasking fault-tolerance to a different class of faults is NP-complete.
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