The Experts below are selected from a list of 116865 Experts worldwide ranked by ideXlab platform
Karama Kanoun - One of the best experts on this subject based on the ideXlab platform.
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web Service Availability impact of error recovery and traffic model
Reliability Engineering & System Safety, 2005Co-Authors: Magnos Martinello, Mohamed Kaâniche, Karama KanounAbstract:Internet is often used for transaction based applications such as online banking, stock trading and shopping, where the Service interruption or outages are unacceptable. Therefore, it is important for designers of such applications to analyze how hardware, software and performance related failures affect the quality of Service delivered to the users. This paper presents analytical models for evaluating the Service Availability of web cluster architectures. A composite performance and Availability modeling approach is defined considering various causes of Service unAvailability. In particular, web cluster systems are modeled taking into account: two error recovery strategies (client transparent and non-client-transparent) as well as two traffic models (Poisson and modulated Poisson). Sensitivity analysis results are presented to show their impact on the web Service Availability. The obtained results provide useful guidelines to web designers.
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Web Service Availability—impact of error recovery and traffic model
Reliability Engineering & System Safety, 2005Co-Authors: Magnos Martinello, Mohamed Kaâniche, Karama KanounAbstract:Internet is often used for transaction based applications such as online banking, stock trading and shopping, where the Service interruption or outages are unacceptable. Therefore, it is important for designers of such applications to analyze how hardware, software and performance related failures affect the quality of Service delivered to the users. This paper presents analytical models for evaluating the Service Availability of web cluster architectures. A composite performance and Availability modeling approach is defined considering various causes of Service unAvailability. In particular, web cluster systems are modeled taking into account: two error recovery strategies (client transparent and non-client-transparent) as well as two traffic models (Poisson and modulated Poisson). Sensitivity analysis results are presented to show their impact on the web Service Availability. The obtained results provide useful guidelines to web designers.
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SAFECOMP - Web Service Availability – Impact of Error Recovery
Lecture Notes in Computer Science, 2003Co-Authors: Magnos Martinello, Mohamed Kaâniche, Karama KanounAbstract:Growing usage and diversity of applications on the Internet make the issue of assessing the web Service Availability increasingly important. The Internet is often used for transaction based applications such as online banking, stock trading, shopping, where the Service interruption or outages are unacceptable. Therefore, it is important for the developers of such applications to analyze during the design phase how hardware, software and performance related failures affect the quality of Service delivered to the users. This paper presents analytical models in order to study the Availability of web Services implemented on web clusters. In particular, a composite performance and Availability modeling approach is considered where various causes of Service unAvailability and two different recovery strategies are taken into account. For illustration purposes, sensitivity analysis results are presented to show the impact on the web Service Availability of various assumptions concerning the architecture, the servers load, as well as the failure and recovery processes.
Magnos Martinello - One of the best experts on this subject based on the ideXlab platform.
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web Service Availability impact of error recovery and traffic model
Reliability Engineering & System Safety, 2005Co-Authors: Magnos Martinello, Mohamed Kaâniche, Karama KanounAbstract:Internet is often used for transaction based applications such as online banking, stock trading and shopping, where the Service interruption or outages are unacceptable. Therefore, it is important for designers of such applications to analyze how hardware, software and performance related failures affect the quality of Service delivered to the users. This paper presents analytical models for evaluating the Service Availability of web cluster architectures. A composite performance and Availability modeling approach is defined considering various causes of Service unAvailability. In particular, web cluster systems are modeled taking into account: two error recovery strategies (client transparent and non-client-transparent) as well as two traffic models (Poisson and modulated Poisson). Sensitivity analysis results are presented to show their impact on the web Service Availability. The obtained results provide useful guidelines to web designers.
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Web Service Availability—impact of error recovery and traffic model
Reliability Engineering & System Safety, 2005Co-Authors: Magnos Martinello, Mohamed Kaâniche, Karama KanounAbstract:Internet is often used for transaction based applications such as online banking, stock trading and shopping, where the Service interruption or outages are unacceptable. Therefore, it is important for designers of such applications to analyze how hardware, software and performance related failures affect the quality of Service delivered to the users. This paper presents analytical models for evaluating the Service Availability of web cluster architectures. A composite performance and Availability modeling approach is defined considering various causes of Service unAvailability. In particular, web cluster systems are modeled taking into account: two error recovery strategies (client transparent and non-client-transparent) as well as two traffic models (Poisson and modulated Poisson). Sensitivity analysis results are presented to show their impact on the web Service Availability. The obtained results provide useful guidelines to web designers.
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SAFECOMP - Web Service Availability – Impact of Error Recovery
Lecture Notes in Computer Science, 2003Co-Authors: Magnos Martinello, Mohamed Kaâniche, Karama KanounAbstract:Growing usage and diversity of applications on the Internet make the issue of assessing the web Service Availability increasingly important. The Internet is often used for transaction based applications such as online banking, stock trading, shopping, where the Service interruption or outages are unacceptable. Therefore, it is important for the developers of such applications to analyze during the design phase how hardware, software and performance related failures affect the quality of Service delivered to the users. This paper presents analytical models in order to study the Availability of web Services implemented on web clusters. In particular, a composite performance and Availability modeling approach is considered where various causes of Service unAvailability and two different recovery strategies are taken into account. For illustration purposes, sensitivity analysis results are presented to show the impact on the web Service Availability of various assumptions concerning the architecture, the servers load, as well as the failure and recovery processes.
Jianhua Zhang - One of the best experts on this subject based on the ideXlab platform.
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A Charging Strategy for PV-Based Battery Switch Stations Considering Service Availability and Self-Consumption of PV Energy
IEEE Transactions on Industrial Electronics, 2015Co-Authors: Nian Liu, Qifang Chen, Xinyi Lu, Jie Liu, Jianhua ZhangAbstract:The photovoltaic (PV)-based battery switch station (BSS) is one of typical integration systems to implement a solar-to-vehicle system. The charging strategy is important for the operation of the PV-based BSS. Generally, instant charging strategy for swapped electric vehicle (EV) batteries can keep the Availability of battery-swapping Service at a high level. However, it is always accompanied with the possibility of bringing a negative effect on the utilization of PV energy. The contribution of this paper is mainly on a novel charging strategy for the PV-based BSS considering the Service Availability and self-consumption of the PV energy. First, considering the features of the PV-based BSS, evaluation indexes for the operation performance are defined, including the Availability of battery-swapping Service, self-consumption of the PV energy, and operation profit. Second, the charging strategy is proposed, including a battery-swapping Service model and a power distribution model. In order to guarantee the Service Availability, the battery-swapping Service model is used to decide the lower limit of charging power based on short-term forecasting results of EV requirements. The power distribution model is obliged to dispatch the charging power supplied by the PV system and power grid. Finally, in the case study, the operation of the BSS is simulated with the instant charging strategy and the proposed strategy under different scenarios. From the analysis of results, the proposed strategy can effectively improve the self-consumption of PV energy with the premise of guaranteeing the Availability of the battery-swapping Service.
Katinka Wolter - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Service Availability for time-triggered rejuvenation policies
Journal of Systems and Software, 2010Co-Authors: Felix Salfner, Katinka WolterAbstract:In this paper we investigate the effect of three time-triggered system rejuvenation policies on Service Availability using a queuing model. The model is formulated as an extended stochastic Petri net using a variety of distributions for times between state changes. We define a metric for steady-state Service Availability and derive how it can be estimated from the models in a hybrid approach combining simulation and analytical reasoning. We further analyze time-to-failure of systems with rejuvenation. Experiments show that the optimal rejuvenation interval as well as the achievable Service Availability improvement depend significantly on system utilization. The experiments also show that Service Availability can deviate significantly from steady-state system Availability. For low utilization all rejuvenation policies perform well. For medium utilization, one policy is significantly inferior to the other two, while for high utilization, no rejuvenation should be performed at all.
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a petri net model for Service Availability in redundant computing systems
Winter Simulation Conference, 2009Co-Authors: Felix Salfner, Katinka WolterAbstract:In this paper we present and analyse a coloured stochastic Petri net model of a redundant fault-tolerant system. As our measure of interest we are interested in a dependability metric, i.e., Service Availability. Service Availability is defined as the number of successfully completed jobs relative to the total number of arrived jobs. This paper is the first step towards a comprehensive comparison of redundancy and rejuvenation, i.e., the preventive restart of servers when studying Service Availability. The question we strive to answer in this paper is whether and to what degree additional redundant servers can increase Service Availability in all load scenarios. We find that the first redundant server improves Service Availability by almost 90% in a highly loaded system, while adding a second and third redundant server yields further but much lower improvement. Under low load the benefit of additional servers is not as pronounced.
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Winter Simulation Conference - A Petri net model for Service Availability in redundant computing systems
Proceedings of the 2009 Winter Simulation Conference (WSC), 2009Co-Authors: Felix Salfner, Katinka WolterAbstract:In this paper we present and analyse a coloured stochastic Petri net model of a redundant fault-tolerant system. As our measure of interest we are interested in a dependability metric, i.e., Service Availability. Service Availability is defined as the number of successfully completed jobs relative to the total number of arrived jobs. This paper is the first step towards a comprehensive comparison of redundancy and rejuvenation, i.e., the preventive restart of servers when studying Service Availability. The question we strive to answer in this paper is whether and to what degree additional redundant servers can increase Service Availability in all load scenarios. We find that the first redundant server improves Service Availability by almost 90% in a highly loaded system, while adding a second and third redundant server yields further but much lower improvement. Under low load the benefit of additional servers is not as pronounced.
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APSCC - Service Availability of Systems with Failure Prevention
2008 IEEE Asia-Pacific Services Computing Conference, 2008Co-Authors: Felix Salfner, Katinka WolterAbstract:In this paper we present a queueing model for Service Availability formulated as a Petri net. We define a metric for Service Availability and show how it can be estimated from the model. Assuming that a failure avoidance mechanism is present, we analyze the distribution of time-to-failure. Finally, we show in experiments how Service Availability depends on queue length, utilization and failure prevention and how it relates to steady-state system Availability.
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ISSRE Workshops - A queuing model for Service Availability of systems with rejuvenation
2008 IEEE International Conference on Software Reliability Engineering Workshops (ISSRE Wksp), 2008Co-Authors: Felix Salfner, Katinka WolterAbstract:In this paper we present a queuing model to investigate the effect of time-based system rejuvenation on Service Availability. The model is formulated as a stochastic colored Petri net, which allows us to use realistic distributions such as the lognormal distribution. We define a metric for Service Availability and derive how it can be estimated from the model. Experiments show that the optimal rejuvenation interval as well as the achievable Service Availability improvement depend significantly on system utilization.
Mohamed Kaâniche - One of the best experts on this subject based on the ideXlab platform.
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web Service Availability impact of error recovery and traffic model
Reliability Engineering & System Safety, 2005Co-Authors: Magnos Martinello, Mohamed Kaâniche, Karama KanounAbstract:Internet is often used for transaction based applications such as online banking, stock trading and shopping, where the Service interruption or outages are unacceptable. Therefore, it is important for designers of such applications to analyze how hardware, software and performance related failures affect the quality of Service delivered to the users. This paper presents analytical models for evaluating the Service Availability of web cluster architectures. A composite performance and Availability modeling approach is defined considering various causes of Service unAvailability. In particular, web cluster systems are modeled taking into account: two error recovery strategies (client transparent and non-client-transparent) as well as two traffic models (Poisson and modulated Poisson). Sensitivity analysis results are presented to show their impact on the web Service Availability. The obtained results provide useful guidelines to web designers.
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Web Service Availability—impact of error recovery and traffic model
Reliability Engineering & System Safety, 2005Co-Authors: Magnos Martinello, Mohamed Kaâniche, Karama KanounAbstract:Internet is often used for transaction based applications such as online banking, stock trading and shopping, where the Service interruption or outages are unacceptable. Therefore, it is important for designers of such applications to analyze how hardware, software and performance related failures affect the quality of Service delivered to the users. This paper presents analytical models for evaluating the Service Availability of web cluster architectures. A composite performance and Availability modeling approach is defined considering various causes of Service unAvailability. In particular, web cluster systems are modeled taking into account: two error recovery strategies (client transparent and non-client-transparent) as well as two traffic models (Poisson and modulated Poisson). Sensitivity analysis results are presented to show their impact on the web Service Availability. The obtained results provide useful guidelines to web designers.
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SAFECOMP - Web Service Availability – Impact of Error Recovery
Lecture Notes in Computer Science, 2003Co-Authors: Magnos Martinello, Mohamed Kaâniche, Karama KanounAbstract:Growing usage and diversity of applications on the Internet make the issue of assessing the web Service Availability increasingly important. The Internet is often used for transaction based applications such as online banking, stock trading, shopping, where the Service interruption or outages are unacceptable. Therefore, it is important for the developers of such applications to analyze during the design phase how hardware, software and performance related failures affect the quality of Service delivered to the users. This paper presents analytical models in order to study the Availability of web Services implemented on web clusters. In particular, a composite performance and Availability modeling approach is considered where various causes of Service unAvailability and two different recovery strategies are taken into account. For illustration purposes, sensitivity analysis results are presented to show the impact on the web Service Availability of various assumptions concerning the architecture, the servers load, as well as the failure and recovery processes.
