Traditional overlay network simulators provide accurate low-level models of the network hardware and protocols but are but none of them deal with the problem of trust in the large scale overlay networks. We tackle this problem by employing a trust overlay simulator, which offer a viable solution to simulate trustworthy behavior in overlay networks. With this simulator, we can exam varies kinds of the trust and reputation mechanisms in the overlay environment. We hope that this simulator will help move the overlay network closer to fulfilling its promise by developing and testing trust and reputation-based protocols on it
{"title":"A Generic Trust Overlay Simulator for P2P Networks","authors":"Wei Wang, Guosun Zeng","doi":"10.1109/PRDC.2006.8","DOIUrl":"https://doi.org/10.1109/PRDC.2006.8","url":null,"abstract":"Traditional overlay network simulators provide accurate low-level models of the network hardware and protocols but are but none of them deal with the problem of trust in the large scale overlay networks. We tackle this problem by employing a trust overlay simulator, which offer a viable solution to simulate trustworthy behavior in overlay networks. With this simulator, we can exam varies kinds of the trust and reputation mechanisms in the overlay environment. We hope that this simulator will help move the overlay network closer to fulfilling its promise by developing and testing trust and reputation-based protocols on it","PeriodicalId":314915,"journal":{"name":"2006 12th Pacific Rim International Symposium on Dependable Computing (PRDC'06)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117053111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Advanced data engineering applications require a large-scale storage system that is both scalable and dependable. In such a system, an atomic commit protocol becomes imperative to ensure the consistency and atomicity of transactions. In this paper we present a new commit protocol, BA-1.5PC, which is well tailored to such distributed storage environments as autonomous disks that use a primary-backup storage schema. The protocol achieves an efficient commit process while also guaranteeing a high dependability by combining several approaches: (1) a low-overhead log mechanism that eliminates blocking disk I/Os, (2) removing the voting phase from commit processing to gain a faster commit process, and (3) a primary-backup assisted recovery strategy to enhance dependability in the presence of possible failures, so that a master failure in the decision phase are not block prepared cohorts of a transaction. Experiments were carried out on a trial version of an autonomous disks system to verify its efficiency. The results indicate that this protocol significantly outperforms several well-known commit protocols in terms of transaction throughput
{"title":"An Efficient Commit Protocol Exploiting Primary-Backup Placement in a Distributed Storage System","authors":"Xiangyong Ouyang, Tomohiro Yoshihara, H. Yokota","doi":"10.1109/PRDC.2006.17","DOIUrl":"https://doi.org/10.1109/PRDC.2006.17","url":null,"abstract":"Advanced data engineering applications require a large-scale storage system that is both scalable and dependable. In such a system, an atomic commit protocol becomes imperative to ensure the consistency and atomicity of transactions. In this paper we present a new commit protocol, BA-1.5PC, which is well tailored to such distributed storage environments as autonomous disks that use a primary-backup storage schema. The protocol achieves an efficient commit process while also guaranteeing a high dependability by combining several approaches: (1) a low-overhead log mechanism that eliminates blocking disk I/Os, (2) removing the voting phase from commit processing to gain a faster commit process, and (3) a primary-backup assisted recovery strategy to enhance dependability in the presence of possible failures, so that a master failure in the decision phase are not block prepared cohorts of a transaction. Experiments were carried out on a trial version of an autonomous disks system to verify its efficiency. The results indicate that this protocol significantly outperforms several well-known commit protocols in terms of transaction throughput","PeriodicalId":314915,"journal":{"name":"2006 12th Pacific Rim International Symposium on Dependable Computing (PRDC'06)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117252696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is well-known that accurate reliability estimates can be obtained by using software reliability models only in the later phase of software testing. However, prediction in the early phase is important for cost-effective and timely management. Also this requirement can be achieved with information from previous releases or similar projects. This basic idea has been implemented with nonhomogeneous Poisson process (NHPP) models by assuming the same testing/debugging environment for similar projects or successive releases. In this paper we study an approach to using past fault-related data with artificial neural network (ANN) models to improve reliability predictions in the early testing phase. Numerical examples are shown with both actual and simulated datasets. Better performance of early prediction is observed compared with original ANN model with no such historical fault-related data incorporated. Also, the problem of optimal switching point from the proposed approach to original ANN model is studied, with three numerical examples
{"title":"Early Software Reliability Prediction with ANN Models","authors":"Q. Hu, M. Xie, S. Ng","doi":"10.1109/PRDC.2006.30","DOIUrl":"https://doi.org/10.1109/PRDC.2006.30","url":null,"abstract":"It is well-known that accurate reliability estimates can be obtained by using software reliability models only in the later phase of software testing. However, prediction in the early phase is important for cost-effective and timely management. Also this requirement can be achieved with information from previous releases or similar projects. This basic idea has been implemented with nonhomogeneous Poisson process (NHPP) models by assuming the same testing/debugging environment for similar projects or successive releases. In this paper we study an approach to using past fault-related data with artificial neural network (ANN) models to improve reliability predictions in the early testing phase. Numerical examples are shown with both actual and simulated datasets. Better performance of early prediction is observed compared with original ANN model with no such historical fault-related data incorporated. Also, the problem of optimal switching point from the proposed approach to original ANN model is studied, with three numerical examples","PeriodicalId":314915,"journal":{"name":"2006 12th Pacific Rim International Symposium on Dependable Computing (PRDC'06)","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126195659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Leader election is one of the fundamental problems in distributed systems. A leader is a correct process that can be used to coordinate the work of a set of processes. An algorithm has to implement two properties to solve the leader election problem: (1) safety, (2) liveness. In this work we show that the stabilization property is not necessary for the leader election problem. We do this by examine the ability to solve leader election in the FAR model. The FAR model does neither assume the existence of an upper bound on the communication or computation delays nor that the system stabilizes. Instead it assumes that the system is in a certain balance: computation is not infinitely fast, the communication subsystem has rudimentary congestion control and the average response time between two correct processes is finite. Our contribution is twofold: (1) we show that leader election is not solvable in the pure FAR model and (2) that it becomes solvable with local clocks with a bounded drift rate
{"title":"Leader Election in the Timed Finite Average Response Time Model","authors":"C. Fetzer, Martin Süßkraut","doi":"10.1109/PRDC.2006.41","DOIUrl":"https://doi.org/10.1109/PRDC.2006.41","url":null,"abstract":"Leader election is one of the fundamental problems in distributed systems. A leader is a correct process that can be used to coordinate the work of a set of processes. An algorithm has to implement two properties to solve the leader election problem: (1) safety, (2) liveness. In this work we show that the stabilization property is not necessary for the leader election problem. We do this by examine the ability to solve leader election in the FAR model. The FAR model does neither assume the existence of an upper bound on the communication or computation delays nor that the system stabilizes. Instead it assumes that the system is in a certain balance: computation is not infinitely fast, the communication subsystem has rudimentary congestion control and the average response time between two correct processes is finite. Our contribution is twofold: (1) we show that leader election is not solvable in the pure FAR model and (2) that it becomes solvable with local clocks with a bounded drift rate","PeriodicalId":314915,"journal":{"name":"2006 12th Pacific Rim International Symposium on Dependable Computing (PRDC'06)","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128066697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Our increasing reliance on the information and services provided by modern Web servers mandates that these services be offered with superior performance and reliability. The architecture of a Web server has a profound impact on its performance and reliability. One of the dimensions used to characterize the architecture of a Web server is the processing model employed in the server, which describes the type of process or threading model used to support a Web server operation. The main options for a processing model are process-based, thread-based or a hybrid of the process-based and the thread-based models. These options have unique advantages and disadvantages in terms of their performance and reliability tradeoffs. In this paper we propose an analysis methodology based on the stochastic reward net (SRN) modeling paradigm to quantify the performance and the reliability tradeoffs in the process-based and the thread-based Web server software architectures. We demonstrate the capability of the methodology to facilitate systematic, quantitative tradeoffs using several examples
{"title":"Performance and Reliability Analysis ofWeb Server Software Architectures","authors":"S. Gokhale, Paul J. Vandal, Jijun Lu","doi":"10.1109/PRDC.2006.50","DOIUrl":"https://doi.org/10.1109/PRDC.2006.50","url":null,"abstract":"Our increasing reliance on the information and services provided by modern Web servers mandates that these services be offered with superior performance and reliability. The architecture of a Web server has a profound impact on its performance and reliability. One of the dimensions used to characterize the architecture of a Web server is the processing model employed in the server, which describes the type of process or threading model used to support a Web server operation. The main options for a processing model are process-based, thread-based or a hybrid of the process-based and the thread-based models. These options have unique advantages and disadvantages in terms of their performance and reliability tradeoffs. In this paper we propose an analysis methodology based on the stochastic reward net (SRN) modeling paradigm to quantify the performance and the reliability tradeoffs in the process-based and the thread-based Web server software architectures. We demonstrate the capability of the methodology to facilitate systematic, quantitative tradeoffs using several examples","PeriodicalId":314915,"journal":{"name":"2006 12th Pacific Rim International Symposium on Dependable Computing (PRDC'06)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123626509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Formal methods for verification of software systems often face the problem of state explosion and complexity. We propose a divide and conquer methodology which leads to component-based verification and analysis of formal requirements specifications expressed using software cost reduction (SCR) models. This paper presents a novel decomposition methodology which identifies components in the given SCR specification and automates related abstraction methods. Further, we propose a verification strategy for modular and decomposable software models. Efficient verification of SCR models is achieved through the use of invariants and proof compositions. Experimental validation of our methodology brought to light the importance of modularity, encapsulation, information hiding and the avoidance of global variables in the context of formal specification models. The advantages of the compositional verification strategy are demonstrated in the analysis of the personnel access control system. Our approach offers significant savings in terms of time and memory requirements needed to perform formal system verification
{"title":"A Strategy for Verification of Decomposable SCR Models","authors":"Dejan Desovski, B. Cukic","doi":"10.1109/PRDC.2006.16","DOIUrl":"https://doi.org/10.1109/PRDC.2006.16","url":null,"abstract":"Formal methods for verification of software systems often face the problem of state explosion and complexity. We propose a divide and conquer methodology which leads to component-based verification and analysis of formal requirements specifications expressed using software cost reduction (SCR) models. This paper presents a novel decomposition methodology which identifies components in the given SCR specification and automates related abstraction methods. Further, we propose a verification strategy for modular and decomposable software models. Efficient verification of SCR models is achieved through the use of invariants and proof compositions. Experimental validation of our methodology brought to light the importance of modularity, encapsulation, information hiding and the avoidance of global variables in the context of formal specification models. The advantages of the compositional verification strategy are demonstrated in the analysis of the personnel access control system. Our approach offers significant savings in terms of time and memory requirements needed to perform formal system verification","PeriodicalId":314915,"journal":{"name":"2006 12th Pacific Rim International Symposium on Dependable Computing (PRDC'06)","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134346810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Most of the models for software reliability analysis are based on reliability growth models which deal with the fault detection process only. In this paper, some useful approaches to the modeling of both software fault detection and fault correction processes are discussed. Since the estimation of model parameters in software testing is essential to give accurate prediction and help make the right decision about software release, the problem of estimating the parameters is addressed. Taking into account the dependency between the fault correction process and the fault detection process, a new explicit formula for the likelihood function is derived and the maximum likelihood estimates are obtained under various time delay assumptions. An actual set of data from a software development project is used as an illustrative example. A Monte Carlo simulation is carried out to compare the predictive capability between the LSE method and the MLE method
{"title":"Detection and Correction Process Modeling Considering the Time Dependency","authors":"Y. Wu, Q. Hu, M. Xie, S. Ng","doi":"10.1109/PRDC.2006.27","DOIUrl":"https://doi.org/10.1109/PRDC.2006.27","url":null,"abstract":"Most of the models for software reliability analysis are based on reliability growth models which deal with the fault detection process only. In this paper, some useful approaches to the modeling of both software fault detection and fault correction processes are discussed. Since the estimation of model parameters in software testing is essential to give accurate prediction and help make the right decision about software release, the problem of estimating the parameters is addressed. Taking into account the dependency between the fault correction process and the fault detection process, a new explicit formula for the likelihood function is derived and the maximum likelihood estimates are obtained under various time delay assumptions. An actual set of data from a software development project is used as an illustrative example. A Monte Carlo simulation is carried out to compare the predictive capability between the LSE method and the MLE method","PeriodicalId":314915,"journal":{"name":"2006 12th Pacific Rim International Symposium on Dependable Computing (PRDC'06)","volume":"47 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132148473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Availability is an important attribute of optical transport networks, and is enabled through many alternative restoration schemes. Different restoration schemes tradeoff network cost, as measured by provisioned capacity, and network reliability to match diverse application needs. We provide a systematic quantification of these tradeoffs for commonly employed restoration schemes and illustrate them for several networks. In this paper, we analyze a dedicated capacity 1+1 protection scheme and two commonly employed shared capacity mesh restoration schemes: path and link based restoration
{"title":"Restoration Strategies In Mesh Optical Networks: Cost Vs. Service Availability","authors":"D. Jeske, A. Sampath","doi":"10.1109/PRDC.2006.55","DOIUrl":"https://doi.org/10.1109/PRDC.2006.55","url":null,"abstract":"Availability is an important attribute of optical transport networks, and is enabled through many alternative restoration schemes. Different restoration schemes tradeoff network cost, as measured by provisioned capacity, and network reliability to match diverse application needs. We provide a systematic quantification of these tradeoffs for commonly employed restoration schemes and illustrate them for several networks. In this paper, we analyze a dedicated capacity 1+1 protection scheme and two commonly employed shared capacity mesh restoration schemes: path and link based restoration","PeriodicalId":314915,"journal":{"name":"2006 12th Pacific Rim International Symposium on Dependable Computing (PRDC'06)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114093070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Although mutation is one of the practical ways of enhancing the effectiveness of the test cases to be applied to an application under test, it could be sometimes infeasible for there being too many assumed faults and mutants to be operated in a larger scale system so that the mutation operating becomes time-consuming and even prohibited. Therefore, the number of faults assumed to exist in the software under test should be reduced. Fault collapsing is a common way of reducing the number of faults in hardware testing. However, this strategy can now be well implanted into the area of software testing. In this paper, we utilize the concept of fault dominance and equivalence, which has long been used in hardware testing, for revealing a novel way of reducing the number of faults assumed to hide in software systems. Once the number of faults assumed in software is decreased sharply, the effectiveness of mutation testing would be greatly enhanced. Examples and experimental results are presented to illustrate the effectiveness and the helpfulness of the technology proposed in the paper
{"title":"A New Approach to Improving the Test Effectiveness in Software Testing Using Fault Collapsing","authors":"Shiyi Xu","doi":"10.1109/PRDC.2006.10","DOIUrl":"https://doi.org/10.1109/PRDC.2006.10","url":null,"abstract":"Although mutation is one of the practical ways of enhancing the effectiveness of the test cases to be applied to an application under test, it could be sometimes infeasible for there being too many assumed faults and mutants to be operated in a larger scale system so that the mutation operating becomes time-consuming and even prohibited. Therefore, the number of faults assumed to exist in the software under test should be reduced. Fault collapsing is a common way of reducing the number of faults in hardware testing. However, this strategy can now be well implanted into the area of software testing. In this paper, we utilize the concept of fault dominance and equivalence, which has long been used in hardware testing, for revealing a novel way of reducing the number of faults assumed to hide in software systems. Once the number of faults assumed in software is decreased sharply, the effectiveness of mutation testing would be greatly enhanced. Examples and experimental results are presented to illustrate the effectiveness and the helpfulness of the technology proposed in the paper","PeriodicalId":314915,"journal":{"name":"2006 12th Pacific Rim International Symposium on Dependable Computing (PRDC'06)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114200610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently, measurement based studies of software systems proliferated, reflecting an increasingly empirical focus on system availability, reliability, aging and fault tolerance. However, it is a non-trivial, error-prone, arduous, and time-consuming task even for experienced system administrators and statistical analysis to know what a reasonable set of steps should include to model and successfully predict performance variables or system failures of a complex software system. Reported results are fragmented and focus on applying statistical regression techniques to captured numerical system data. In this paper, we propose a best practice guide for building empirical models based on our experience with forecasting Apache Web server performance variables and forecasting call availability of a real world telecommunication system. To substantiate the presented guide and to demonstrate our approach step-by-step we model and predict the response time and the amount of free physical memory of an Apache Web server system. Additionally, we present concrete results for a) variable selection where we cross benchmark three procedures, b) empirical model building where we cross benchmark four techniques and c) sensitivity analysis. This best practice guide intends to assist in configuring modeling approaches systematically for best estimation and prediction results
{"title":"A Best Practice Guide to Resources Forecasting for the Apache Webserver","authors":"G. A. Hoffmann, Kishor S. Trivedi, M. Malek","doi":"10.1109/PRDC.2006.5","DOIUrl":"https://doi.org/10.1109/PRDC.2006.5","url":null,"abstract":"Recently, measurement based studies of software systems proliferated, reflecting an increasingly empirical focus on system availability, reliability, aging and fault tolerance. However, it is a non-trivial, error-prone, arduous, and time-consuming task even for experienced system administrators and statistical analysis to know what a reasonable set of steps should include to model and successfully predict performance variables or system failures of a complex software system. Reported results are fragmented and focus on applying statistical regression techniques to captured numerical system data. In this paper, we propose a best practice guide for building empirical models based on our experience with forecasting Apache Web server performance variables and forecasting call availability of a real world telecommunication system. To substantiate the presented guide and to demonstrate our approach step-by-step we model and predict the response time and the amount of free physical memory of an Apache Web server system. Additionally, we present concrete results for a) variable selection where we cross benchmark three procedures, b) empirical model building where we cross benchmark four techniques and c) sensitivity analysis. This best practice guide intends to assist in configuring modeling approaches systematically for best estimation and prediction results","PeriodicalId":314915,"journal":{"name":"2006 12th Pacific Rim International Symposium on Dependable Computing (PRDC'06)","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132930703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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