Preemptive regression testing of workflow-based web services

published_or_final_versio

Test Case Prioritization for Audit Testing of Evolving Web Services using Information Retrieval Techniques

Web services evolve frequently to meet new busi- ness demands and opportunities. However, service changes may affect service compositions that are currently consuming the services. Hence, audit testing (a form of regression testing in charge of checking for compatibility issues) is needed. As service compositions are often in continuous operation and the external services have limited (expensive) access when invoked for testing, audit testing has severe time and resources constraints, which make test prioritization a crucial technique (only the highest priority test cases will be executed). This paper presents a novel approach to the prioritization of audit test cases using information retrieval. This approach matches a service change description with the code portions exercised by the relevant test cases. So, test cases are prioritized based on their relevance to the service change. We evaluate the proposed approach on a system that composes services from eBay and Google

プログラムの解析、テスト、修復のための表現学習

学位の種別: 課程博士審査委員会委員 : （主査）東京大学特任准教授 松尾 豊, 東京大学教授 和泉 潔, 東京大学准教授 阿部 力也, 東京大学准教授 森 純一郎, 国立情報学研究所教授 蓮尾 一郎University of Tokyo(東京大学

Enhancing coverage adequacy of service compositions after runtime adaptation

Laufzeitüberwachung (engl. runtime monitoring) ist eine wichtige Qualitätssicherungs-Technik für selbstadaptive Service-Komposition. Laufzeitüberwachung überwacht den Betrieb der Service-Komposition. Zur Bestimmung der Genauigkeit von Software-Tests werden häufig Überdeckungskriterien verwendet. Überdeckungskriterien definieren Anforderungen die Software-Tests erfüllen muss. Wegen ihrer wichtigen Rolle im Software-Testen haben Forscher Überdeckungskriterien an die Laufzeitüberwachung von Service-Komposition angepasst. Die passive Art der Laufzeitüberwachung und die adaptive Art der Service-Komposition können die Genauigkeit von Software-Tests zur Laufzeit negativ beeinflussen. Dies kann jedoch die Zuversicht in der Qualität der Service-Komposition begrenzen. Um die Überdeckung selbstadaptiver Service-Komposition zur Laufzeit zu verbessern, untersucht diese Arbeit, wie die Laufzeitüberwachung und Online-Testen kombiniert werden können. Online-Testen bedeutet dass Testen parallel zu der Verwendung einer Service-Komposition erfolgt. Zunächst stellen wir einen Ansatz vor, um gültige Execution-Traces für Service-Komposition zur Laufzeit zu bestimmen. Der Ansatz berücksichtigt die Execution-Traces von Laufzeitüberwachung und (Online)-Testen. Er berücksichtigt Änderungen im Workflow und Software-Services eines Service-Komposition. Zweitens, definieren wir Überdeckungskriterien für Service-Komposition. Die Überdeckungskriterien berücksichtigen Ausführungspläne einer Service-Komposition und berücksichtigen die Überdeckung für Software-Services und die Service-Komposition. Drittens stellen wir Online-Testfälle Priorisierungs Techniken, um die Abdeckungniveau einer Service-Komposition schneller zu erreichen. Die Techniken berücksichtigen die Überdeckung einer Service-Komposition durch beide Laufzeitüberwachung und Online-Tests. Zusätzlich, berücksichtigen sie die Ausführungszeit von Testfällen und das Nutzungsmodell der Service-Komposition. Viertens stellen wir einen Rahmen für die Laufzeitüberwachung und Online-Testen von Software-Services und Service-Komposition, genannt PROSA, vor. PROSA bietet technische Unterstützung für die oben genannten Beiträge. Wir evaluieren die Beiträge anhand einer beispielhaften Service-Komposition, die häufig in dem Forschungsgebiet Service-oriented Computing eingesetzt wird.Runtime monitoring (or monitoring for short) is a key quality assurance technique for self-adaptive service compositions. Monitoring passively observes the runtime behaviour of service compositions. Coverage criteria are extensively used for assessing the adequacy (or thoroughness) of software testing. Coverage criteria specify certain requirements on software testing. The importance of coverage criteria in software testing has motivated researchers to adapt them to the monitoring of service composition. However, the passive nature of monitoring and the adaptive nature of service composition could negatively influence the adequacy of monitoring, thereby limiting the confidence in the quality of the service composition. To enhance coverage adequacy of self-adaptive service compositions at runtime, this thesis investigates how to combine runtime monitoring and online testing. Online testing means testing a service composition in parallel to its actual usage and operation. First, we introduce an approach for determining valid execution traces for service compositions at runtime. The approach considers execution traces of both monitoring and (online) testing. It considers modifications in both workflow and constituent services of a service composition. Second, we define coverage criteria for service compositions. The criteria consider execution plans of a service composition for coverage assessment and consider the coverage of an abstract service and the overall service composition. Third, we introduce online-test-case prioritization techniques to achieve a faster coverage of a service composition. The techniques employ coverage of a service composition from both monitoring and online testing, execution time of test cases, and the usage model of the service composition. Fourth, we introduce a framework for monitoring and online testing of services and service compositions called PROSA. PROSA provides technical support for the aforementioned contributions. We evaluate the contributions of this thesis using service compositions frequently used in service-oriented computing research

Optimization of System Identification for Multi-Rail DC-DC Power Converters

Ph. D. Thesis.There have been many recursive algorithms investigated and introduced in real time parameter estimation of Switch Mode Power Converters (SMPCs) to improve estimation performance in terms of faster convergence speed, lower computational cost and higher estimation accuracy. These algorithms, including Dichotomous Coordinate Descent (DCD) - Recursive Least Square (RLS), Kalman Filter (KF) and Fast Affine Projection (FAP), etc., are commonly applied for performance comparison of system identification of single-rail power converters. When they need to be used in multi-rail architectures with a single centralized controller, the computational burden on the processor becomes significant. Typically, the computational effort is directly proportional to the number of converters/rails. This thesis presents an iterative decimation approach to significantly alleviate the computational burden of centralized controllers applying real-time recursive system identification algorithms in multirail power converters. The proposed approach uses a flexible and adjustable update rate rather than a fixed rate, as opposed to conventional adaptive filters. In addition, the step size/forgetting factors are varied, as well, corresponding to different iteration stages. As a result, reduced computational burden and faster model update can be achieved. Recursive algorithms, such as Recursive Least Square (RLS), Affine Projection (AP) and Kalman Filter (KF), contain two important updates per iteration cycle. Covariance Matrix Approximation (CMA) update and the Gradient Vector (GV) update. Usually, the computational effort of updating Covariance Matrix Approximation (CMA) requires greater computational effort than that of updating Gradient Vector (GV). Therefore, in circumstances where the sampled data in the regressor does not experience significant fluctuations, re-using the Covariance Matrix Approximation (CMA), calculated from the last iteration cycle for the current update can result in computational cost savings for real- time system identification. In this thesis, both iteration rate adjustment and Covariance Matrix Approximation (CMA) re-cycling are combined and applied to simultaneously identify the power converter model in a three-rail power conversion architecture. Besides, in multi-rail architectures, due to the high likelihood of the at-the-same-time need for real time system identification of more than one rail, it is necessary to prioritize each rail to guarantee rails with higher priority being identified first and avoid jam. In the thesis, a workflow, which comprises sequencing rails and allocating system identification task into selected rails, was proposed. The multi-respect workflow, featured of being dynamic, selectively pre-emptive, cost saving, is able to flexibly change ranks of each rail based on the application importance of rails and the severity of abrupt changes that rails are suffering to optimize waiting time and make-span of rails with higher priorities