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U. Dinesh Kumar - One of the best experts on this subject based on the ideXlab platform.

  • Optimal Component Selection Problem for Cots Based Software System under Consensus Recovery Block Scheme: A Goal Programming Approach
    International Journal of Computer Applications, 2012
    Co-Authors: Deepak Kumar, P. K. Kapur, P. C. Jha, U. Dinesh Kumar
    Abstract:

    Cost, reliability and time are the three main quality attributes of a software system. Now days much software are designed on COTS component in order to facilitate timely development with reduced cost and improved reliability. Software deigned to handle critical control systems have very high reliability requirements. Fault tolerance is designed in these systems for some or all of the software modules so that execution can be resumed even after failure with minimal loss of data and time. Designing fault tolerance requires extra resources. Even though reliability requirement are very high the developers can’t spend endless resources on any project. This is a trade off problem between reliability and cost. Many such problems have been discussed in literature considering distinct objectives and constraints and have given good results. An effective approach to discuss this problem is to formulate a multi-objective problem with cost minimization and reliability maximization as the two objectives with an upper bound on cost and lower bound on reliability. In this paper we formulate this bi-criteria problem and discuss the solution methodology. The problem is formulated for consensus Recovery Block fault tolerant scheme. In case a feasible solution for the problem exists, criterion vector approach is used to solve the problem and otherwise if the bounds are contradictory a goal programming approach is used to solve the problem to obtain a compromised solution. Alternative goal solutions are obtained assigning different weights for the objective to facilitate the decision maker with correct decision.

  • Optimal component selection of COTS based software system under Recovery Block scheme incorporating execution time
    International Journal of Systems Assurance Engineering and Management, 2010
    Co-Authors: P. C. Jha, P. K. Kapur, Ritu Arora, U. Dinesh Kumar
    Abstract:

    For the effective development of the faulttolerant software system, cost, reliability and time are the important aspects to be considered. Ideally, any software system must be constructed in such a way that execution can resume even after failure without the loss of data and time. Such software systems which can continue execution even after the occurrence of faults are called fault tolerant software. Software is developed to perform a pre-decided number of functions that can be executed by the software system. When fault occurs, one of the redundant components get executed and prevents system failure. Advancement of technology and increasing software development cost has made the use of commercial off-the-shelf (COTS) software which builds system with reduced risk, cost and development time while increasing functionality and capability of the system. In this paper, two reliability models for fault tolerant Recovery Blocks are discussed. In the first optimization model, we formulate a joint optimization problem in which reliability maximization of software system and execution time minimization for each function of software system are considered under budgetary constraint. In the second model the issue of compatibility among alternatives available for different modules, is discussed. Numerical illustrations are provided to demonstrate the models developed in this paper.

  • Reliability analysis of N‐version programming with deadline mechanism
    International Journal of Quality & Reliability Management, 2000
    Co-Authors: U. Dinesh Kumar
    Abstract:

    In this paper reliability models for fault tolerant N‐version programming and consensus Recovery Block (combination of N‐version programming and Recovery Block) with deadline mechanism are analysed. Explicit expressions for reliability of N‐version programming and consensus Recovery Block with exponential execution times are derived. The paper also presents optimisation models for real time N‐version programming. The objective of the optimisation problem is to maximise reliability of the software satisfying a budget constraint. The paper also includes efficient branch and bound procedure that can be used to solve the optimisation problem.

  • Optimization models for complex Recovery Block schemes
    Computers & Operations Research, 1999
    Co-Authors: Oded Berman, U. Dinesh Kumar
    Abstract:

    Abstract In this paper we consider three complex Recovery Block schemes: (1) nested Recovery Block; (2) modified Recovery Block; and (3) nested consensus Recovery Block. For all the three models: (1) we derive simple expressions for calculating the system reliability; (2) we investigate how to arrange the versions in a nested Recovery Block and in a nested consensus Recovery Block; and (3) we develop optimization models where the objective is to optimize the reliability satisfying a budget constraint. The paper also includes efficient branch and bound procedures to solve the optimization problems. Two numerical example problems are solved to illustrate the branch and bound technique. Scope and purposes Software has become an integral part of many systems. For systems such as air traffic control, space shuttle, fighter aircraft and automated-guided missiles, it is usually the reliability of computer software that has the most single significant impact on the performance. Virtually, all major military systems are dependent on the correct operation of defense systems’ software. For systems such as air traffic control, fighter aircraft and automated guided missiles, 80% of the life cycle cost is spent on the software. Traditionally, reliability of any hardware and software is improved by introducing redundancy. However, redundant components require additional resources. Therefore, the redundancy level needed to achieve specified reliability must be carefully determined. The main purpose of this paper is to develop reliability prediction techniques and optimization models for important fault-tolerant software such as nested Recovery Block, modified Recovery Block and nested consensus Recovery Block. The methods have significant use in selection of programs in COTS (commercial-off-the-shelf) environment.

  • Optimization models for Recovery Block schemes
    European Journal of Operational Research, 1999
    Co-Authors: Oded Berman, U. Dinesh Kumar
    Abstract:

    This paper presents optimization models for a fault tolerant software by selecting a set of versions for a given program. The objective is to maximize the reliability of the software satisfying a budget limitation. Optimization models are developed for two Block Recovery schemes: (1) independent Recovery Block and (2) consensus Recovery Block. The paper also presents simple formulas to calculate the reliability of the two schemes.

K.h. Kim - One of the best experts on this subject based on the ideXlab platform.

  • A distributed Recovery Block approach to fault-tolerant execution of application tasks in hypercubes
    IEEE Transactions on Parallel and Distributed Systems, 1993
    Co-Authors: K.h. Kim, A. Kavianpour
    Abstract:

    An approach to fault-tolerant execution of real-time application tasks in hypercubes is proposed. The approach is based on the distributed Recovery Block (DRB) scheme and does not require special hardware mechanisms in support of fault tolerance. Each task is assigned to a pair of processors forming a DRB computing station for execution in a dual-redundant and self-checking mode. Assignment of all tasks in an application in such a form is called the full DRB mapping. The DRB scheme was developed as an approach to uniform treatment of hardware and software faults with the effect of fast forward Recovery. However, if the system developer is concerned with hardware fault possibilities only, then forming DRB stations becomes a mechanical process not burdening the application software designer in any way. A procedure for converting an efficient nonredundant task-to-processor mapping into an efficient full DRB mapping is presented. >

  • Implementation of the conversation scheme in message-based distributed computer systems
    IEEE Transactions on Parallel and Distributed Systems, 1992
    Co-Authors: S.-m. Yang, K.h. Kim
    Abstract:

    Several different approaches for implementing conversations in message-based distributed computer systems (DCSs) are discussed. Two different exit control strategies (synchronous and asynchronous) and three different approaches to execution of the conversation acceptance test (centralized, decentralized, and semicentralized) are examined and compared in terms of system performance and implementation cost. An efficient approach to run-time management of Recovery information based on an extension of the Recovery cache scheme is also discussed. The two major types of conversation structures, name-linked Recovery Block and abstract data type conversations, are examined to analyze which execution approaches are the most efficient for each conversation structure. As a case study, an unmanned vehicle system is used to illustrate how the approaches can be used in a realistic real-time application. >

  • FTCS - Approaches to implementation of a repairable distributed Recovery Block scheme
    [1988] The Eighteenth International Symposium on Fault-Tolerant Computing. Digest of Papers, 1
    Co-Authors: K.h. Kim, J.c. Yoon
    Abstract:

    The authors previously proposed (1984) the basic concept of the distributed Recovery Block (DRB) scheme as an approach to uniform treatment of hardware and software faults in real-time applications. Design issues that arise in implementing the DRB scheme are discussed together with some promising approaches. Issues in extending the DRB scheme with the capability of reincorporating a repaired node without disrupting the real-time computing service are also discussed. An experimental implementation of the repairable DRB scheme into a real-time distributed computer system (DCS) testbed and subsequent measurement of the system performance demonstrated the fast forward Recovery capability and the logical soundness of the scheme. >

  • FTCS - A distributed fault tolerant architecture for nuclear reactor and other critical process control applications
    [1991] Digest of Papers. Fault-Tolerant Computing: The Twenty-First International Symposium, 1
    Co-Authors: M. Hecht, J. Agron, H. Hecht, K.h. Kim
    Abstract:

    A distributed fault tolerant system for process control that is based on an enhancement of the distributed Recovery Block (DRB) is described. Fault tolerance provisions in the system cover software faults by use of the DRB; hardware faults by means of replication and the DRB; system software faults by means of replication, loose coupling, periodic status messages, and a restart capability; and network faults by means of replication and diverse interconnection paths. Maintainability is enhanced through an automated restart capability and logging function resident on a system supervisor node. The system, called the extended distributed Recovery Block, or EDRB, has been implemented and integrated into a chemical processing system. >

Sang Lyul Min - One of the best experts on this subject based on the ideXlab platform.

  • worst case timing requirement of real time tasks with time redundancy
    Embedded and Real-Time Computing Systems and Applications, 1999
    Co-Authors: Hyosoon Lee, Heonshik Shin, Sang Lyul Min
    Abstract:

    The improvement of system reliability can be achieved through the use of time redundancy techniques including retry, checkpointing and Recovery Block. The objective of this paper is to analyze the worst case timing requirement of real-time tasks with time redundancy in the presence of multiple transient faults. The timing behavior of system level checkpointing is modeled with additional tasks that save the state of all tasks. The timing information derived in this paper makes time redundancy techniques applicable to real-time systems while keeping the validity of schedulability check developed in the past.

  • RTCSA - Worst case timing requirement of real-time tasks with time redundancy
    Proceedings Sixth International Conference on Real-Time Computing Systems and Applications. RTCSA'99 (Cat. No.PR00306), 1
    Co-Authors: Hyosoon Lee, Heonshik Shin, Sang Lyul Min
    Abstract:

    The improvement of system reliability can be achieved through the use of time redundancy techniques including retry, checkpointing and Recovery Block. The objective of this paper is to analyze the worst case timing requirement of real-time tasks with time redundancy in the presence of multiple transient faults. The timing behavior of system level checkpointing is modeled with additional tasks that save the state of all tasks. The timing information derived in this paper makes time redundancy techniques applicable to real-time systems while keeping the validity of schedulability check developed in the past.

P. C. Jha - One of the best experts on this subject based on the ideXlab platform.

  • Fuzzy Multi-criteria Approach for Component Selection of Fault Tolerant Software System under Consensus Recovery Block Scheme☆
    Procedia Computer Science, 2015
    Co-Authors: Ramandeep Kaur, P. C. Jha, Stuti Arora, Sushila Madan
    Abstract:

    Abstract The vibrant and advanced software development tools not only provide software with versatile functions for radical users but at the same time, an easy to use GUI for naive users. APS (Application Package Software) has provided a customised approach for developing independent software components which are ready to be integrated with existing software systems. The APS along with CBSE (Component Based Software Engineering) has an inordinate potential for reducing development time, cost and effort, which otherwise may extend beyond weeks or months’ time for integration. Further, the CBSE approach promotes software reusability i.e. reusing the available components. A component can be reused after fabrication which will include the fabrication cost and time. For development of economical and reliable software, components can be procured in the form of Commercial off-The Shelf (COTS) components from the vendor or may be developed in-house or can be fabricated. This decision is based on several parameters. The aim of this paper is to select the suitable mix of components using Build-or-buy strategy or considering fabrication and to propose a multi-objective model for software modular system with objective of maximizing reliability while simultaneously minimizing the cost, execution time and Source Lines of Code (SLOC) using Consensus Recovery Block Scheme.

  • fuzzy multi objective build or buy approach for component selection of fault tolerant software system under consensus Recovery Block scheme with mandatory redundancy in critical modules
    Soft Computing, 2014
    Co-Authors: Shivani Bali, P. C. Jha, Dinesh U Kumar, Hoang Pham
    Abstract:

    During the last two decades, there has been a growing interest in component-based software engineering CBSE both in academia and industry. In component-based system development, it is common to identify software modules first. Once they are identified, we need to select appropriate software components for each module. These components can either be bought as commercial off-the-shelf COTS components and probably adapted to work in the software system or can be developed in-house. This is a 'build-or-buy' decision. This paper discusses a framework that helps a developer to decide whether to buy or to build software components while designing a fault-tolerant modular software system. This paper proposes optimisation models for optimal component selection for a fault-tolerant modular software system under the consensus Recovery Block scheme. It is necessary to identify critical modules in the design of a fault-tolerant modular software system and also to develop a system with a built in redundancy for critical modules. Therefore, the first optimisation model is developed for optimal component selection with the dual objective of reliability maximisation and cost minimisation of the overall system under the constraints on the delivery time and criticality of modules. The second optimisation model is an extension of the first optimisation model and discusses the issue of compatibility of components of modules. In practice, it is not possible for management to obtain precise value of reliability, cost, delivery time, etc., therefore both the models are formulated as fuzzy multi-objective optimisation models. A case study of developing a manufacturing system for medium-size enterprise is used to illustrate the proposed methodology.

  • fuzzy optimization approach to component selection of fault tolerant software system
    Memetic Computing, 2014
    Co-Authors: P. C. Jha, Shivani Bali, Dinesh U Kumar, Hoang Pham
    Abstract:

    In developing software systems, a manager’s goal is to design software using limited resources and meet the user requirements. One of the important user requirements concerns the reliability of the software. The decision to choose the right software modules (components) becomes extremely difficult because of the number of parameters to be considered while making the decision. If suitable components are not available, then the decision process is further complicated with build versus buy decisions. In this paper, we have formulated a fuzzy multi-objective approach to optimal decision “build-or-buy” for component selection for a fault-tolerant modular software system under the consensus Recovery Block scheme. A joint optimization model is formulated where the two objectives are maximization of system reliability and minimization of the system cost with a constraint on delivery time. An example of developing a retail system for small-and-medium-size enterprises is used to illustrate the proposed methodology.

  • Optimal Component Selection Problem for Cots Based Software System under Consensus Recovery Block Scheme: A Goal Programming Approach
    International Journal of Computer Applications, 2012
    Co-Authors: Deepak Kumar, P. K. Kapur, P. C. Jha, U. Dinesh Kumar
    Abstract:

    Cost, reliability and time are the three main quality attributes of a software system. Now days much software are designed on COTS component in order to facilitate timely development with reduced cost and improved reliability. Software deigned to handle critical control systems have very high reliability requirements. Fault tolerance is designed in these systems for some or all of the software modules so that execution can be resumed even after failure with minimal loss of data and time. Designing fault tolerance requires extra resources. Even though reliability requirement are very high the developers can’t spend endless resources on any project. This is a trade off problem between reliability and cost. Many such problems have been discussed in literature considering distinct objectives and constraints and have given good results. An effective approach to discuss this problem is to formulate a multi-objective problem with cost minimization and reliability maximization as the two objectives with an upper bound on cost and lower bound on reliability. In this paper we formulate this bi-criteria problem and discuss the solution methodology. The problem is formulated for consensus Recovery Block fault tolerant scheme. In case a feasible solution for the problem exists, criterion vector approach is used to solve the problem and otherwise if the bounds are contradictory a goal programming approach is used to solve the problem to obtain a compromised solution. Alternative goal solutions are obtained assigning different weights for the objective to facilitate the decision maker with correct decision.

  • optimal component selection of cots based software system under consensus Recovery Block scheme incorporating execution time
    International Journal of Reliability Quality and Safety Engineering, 2010
    Co-Authors: P. C. Jha, Shivani Bali, P. K. Kapur, Dinesh U Kumar
    Abstract:

    Computer based systems have increased dramatically in scope, complexity, pervasiveness. Most industries are highly dependent on computers for their basic day to day functioning. Safe & reliable software operations are an essential requirement for many systems across different industries. The number of functions to be included in a software system is decided during the software development. Any software system must be constructed in such a way that execution can resume even after the occurrence of failure with minimal loss of data and time. Such software systems which can continue execution even in presence of faults are called fault tolerant software. When failure occurs one of the redundant software modules get executed and prevent system failure. The fault tolerant software systems are usually developed by integrating COTS (commercial off-the-shelf) software components. The motivation for using COTS components is that they will reduce overall system development costs and reduce development time. In this paper, reliability models for fault tolerant consensus Recovery Blocks are analyzed. In first optimization model, we formulate joint optimization problem in which reliability maximization of software system and execution time minimization for each function of software system are considered under budgetary constraint. In the second model the issue of compatibility among alternatives available for different modules, is discussed. Numerical illustrations are provided to demonstrate the developed models.

A. Kavianpour - One of the best experts on this subject based on the ideXlab platform.

  • A distributed Recovery Block approach to fault-tolerant execution of application tasks in hypercubes
    IEEE Transactions on Parallel and Distributed Systems, 1993
    Co-Authors: K.h. Kim, A. Kavianpour
    Abstract:

    An approach to fault-tolerant execution of real-time application tasks in hypercubes is proposed. The approach is based on the distributed Recovery Block (DRB) scheme and does not require special hardware mechanisms in support of fault tolerance. Each task is assigned to a pair of processors forming a DRB computing station for execution in a dual-redundant and self-checking mode. Assignment of all tasks in an application in such a form is called the full DRB mapping. The DRB scheme was developed as an approach to uniform treatment of hardware and software faults with the effect of fast forward Recovery. However, if the system developer is concerned with hardware fault possibilities only, then forming DRB stations becomes a mechanical process not burdening the application software designer in any way. A procedure for converting an efficient nonredundant task-to-processor mapping into an efficient full DRB mapping is presented. >