High-Level Fault Tolerance in Distributed Programs,

Author(s):  
Erik Seligman ◽  
Adam Beguelin
Author(s):  
DIMITER R. AVRESKY ◽  
PRADEEP K. TAPADIYA

This paper presents a multi-stage software design approach for fault-tolerance. In the first stage, a formalism is introduced to represent the behavior of the system by means of a set of assertions. This formalism enables an execution tree (ET) to be generated where each path from the root to the leaf is, in fact, a well-defined formula. During the automatic generation of the execution tree, properties like completeness and consistency of the set of assertions can be verified and consequently design faults can be revealed. In the second stage, the testing strategy is based on a set of WDFs. This set represents the structural deterministic test for the model of the software system and provides a framework for the generation of a functional deterministic test for the code implementation of the model. This testing strategy can reveal the implementation faults in the program code. In the third stage, the fault-tolerance of the software system against hardware failures is improved in a way such that the design and implementation features obtained from the first two stages are preserved. The proposed approach provides a high level of user-transparency by employing object-oriented principles of data encapsulation and polymorphism. The reliability of the software system against hardware failures is also evaluated. A tool, named Software Fault-Injection Tool (SFIT), is developed to estimate the reliability of a software system.


Author(s):  
Meriem Zaiter ◽  
Salima Hacini ◽  
Zizette Boufaida

The use of distributed systems and IT is growing, with automation being used more and more to facilitate our daily tasks. The need to remotely monitor a patient has driven one of important results of this growth: domestic medical systems. The latter are able to follow and maintain the condition of a patient in the patient's home. Monitoring is important in terms of saving time and also money. However, the critical nature of this task requires a high level of dependability. The aim of dependability is to satisfy the user's goal, which is that whatever the state and context of the overall system, its ability to control the operation of the medical device and to transmit files reporting the patient's condition (normal, critical, alert, etc.) must be continuously assured. This can be ensured by fault tolerance techniques. The authors' objective in this paper is to present a technique for fault tolerance in a domestic medical system. Briefly, their proposal integrates a smart concept into the system: agents for controlling the operation of the medical system and tolerating the faults that can occur.


1994 ◽  
Author(s):  
Tanay Karnik ◽  
Shankar Ramaswamy ◽  
Steve M. Kang ◽  
Prithviraj Banerjee

Author(s):  
Tien Thanh Nguyen ◽  
Mathieu Thevenin ◽  
Anthony Mouraud ◽  
Gwenole Corre ◽  
Olivier Pasquier ◽  
...  

1995 ◽  
Vol 22 (5) ◽  
pp. 861-870 ◽  
Author(s):  
Neil N. Eldin ◽  
Ahmed B. Senouci

This paper discusses the development and the implementation of a neural network for the condition rating of rigid concrete pavements. The condition rating scheme employed by Oregon State Department of Transportation was used as the basis for the development of the network presented. A training set of 298 cases was used to train the network. The network adequately learned the training examples with an average training error of 0.011. A testing set of 3902 cases was used to check the generalization ability of the system. The network was able to determine the correct condition ratings with an average testing error of 0.022. The network ability of dealing with noisy data was also tested. Up to 40% noise was added to the data and introduced to the network. The results showed that the network presented could accurately identify condition rating relationships at high level of noise. Finally, a statistical hypothesis test was conducted to demonstrate the system's fault-tolerance and generalization properties. Key words: neural networks, condition rating, condition index, rigid pavements, pavement distresses, pavement maintenance, fault-tolerance, generalization, noisy data.


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