In recent years the service-oriented design paradigm has enabled applications to be built by incorporating third party services. With the increasing popularity of this new paradigm, many companies and organizations have started to adopt this technology, which has resulted in an increase of the number and variety of third party providers. With the vast improvement of global networking infrastructure, a large number of providers offer their services for worldwide clients. As a result, clients are often presented with a number of providers that offer services with the same or similar functionalities, but differ in terms of non-functional attributes (or Quality of Service – QoS), such as performance. In this environment, the role of provider recommendation has become more important - in assisting clients in choosing the provider that meets their QoS requirement. / In this thesis we focus on provider recommendation based on one of the most important QoS attributes – performance. Specifically, we investigate client-perceived performance, which is the application-level performance measured at the client-side every time the client invokes the service. This performance metric has the advantage of accurately representing client experience, compared to the widely used server-side metrics in the current frameworks (e.g. Service Level Agreement or SLA in Web Services context). As a result, provider recommendation based on this metric will be favourable from the client’s point of view. / In this thesis we address two key research challenges related to provider recommendation based on client-perceived performance - performance assessment and performance prediction. We begin by identifying heterogeneity factors that affect client-perceived performance among clients in a global Internet environment. We then perform extensive real-world experiments to evaluate the significance of each factor to the client-perceived performance. / From our finding on heterogeneity factors, we then develop a performance estimation technique to address performance assessment for cases where direct measurements are unavailable. This technique is based on the generalization concept, i.e. estimating performance based on the measurement gathered by similar clients. A two-stage grouping scheme based on the heterogeneity factors we identified earlier is proposed to address the problem of determining client similarity. We then develop an estimation algorithm and validate it using synthetic data, as well as real world datasets. / With regard to performance prediction, we focus on the medium-term prediction aspect to address the needs of the emerging technology requirements: distinguishing providers based on medium-term (e.g. one to seven days) performance. Such applications are found when the providers require subscription from their clients to access the service. Another situation where the medium-term prediction is important is in temporal-aware selection: the providers need to be differentiated, based on the expected performance of a particular time interval (e.g. during business hours). We investigate the applicability of classical time series prediction methods: ARIMA and exponential smoothing, as well as their seasonal counterparts – seasonal ARIMA and Holt-Winters. Our results show that these existing models lack the ability to capture the important characteristics of client-perceived performance, thus producing poor medium-term prediction. We then develop a medium-term prediction method that is specifically designed to account for the key characteristics of a client-perceived performance series, and to show that our prediction methods produce higher accuracy for medium-term prediction compared to the existing methods. / In order to demonstrate the applicability of our solution in practice, we developed a provider recommendation framework based on client-perceived performance (named PROPPER), which utilizes our findings on performance assessment and prediction. We formulated the recommendation algorithm and evaluated it through a mirror selection case study. It is shown that our framework produces better outcomes in most cases, compared to country-based or geographic distance-based selection schemes, which are the current approach of mirror selection nowadays.

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Reconfiguration dynamique des architectures orientées services

<p>För att dagens system och deras allt mer komplexa applikationer ska kunna integreras med</p><p>varandra krävs det att de kommunicerar via tjänster. Denna tjänsteorienterade integration</p><p>uppnås genom att man använder sig av Service Oriented Architecture (SOA) som bygger på</p><p>löst kopplade tjänster som kommunicerar med varandra på ett standardiserat sätt. En viktig</p><p>del i en integrationslösning är Enterprise Service Bus (ESB). I denna rapport kommer vi</p><p>förklara grunderna i tjänsteorienterad integration och sedan fördjupa oss i ESB. Då ESB är ett</p><p>luddigt begrepp ska vi på ett enkelt och lättbegripligt sätt ge vår syn på begreppet, samt dess</p><p>fördelar och nackdelar. Vi kommer även att ge marknadens syn på ESB genom en</p><p>enkätundersökning som innefattar både leverantörer, konsulter och kunder.</p> / <p>If today’s software systems and their complex applications shall be able to integrate with each</p><p>other, they have to communicate through services. This service oriented integration can be</p><p>accomplished by using Service Oriented Architecture (SOA) where all components are</p><p>loosely coupled and communicate in a standardized way. An important part when building an</p><p>integrated solution is the Enterprise Service Bus (ESB). In this report we will explain the</p><p>basics of SOA and take a more detailed look at the world of ESB. The concept of ESB is not</p><p>well defined and hence means different things to different people. We are going to present an</p><p>interpretation of the ESB and its benefits and disadvantages. To find out what the market</p><p>thinks about ESB we have been talking to producers, consultants and customers.</p>

Efficient organization requires rigorous and systematic information management, which encompasses information processing and decision making. Within the efforts in management science and informatics invested towards advancing the knowledge on, and providing assistance to decision making, this thesis focuses on the conceptualizations and techniques intended to facilitate the identification, evaluation, and selection of decisions during the earliest stages of information systems engineering, whereby the systems of interest are deployed to partly or fully automate various organizational processes, including information processing ones. The overall motivating problem that drove to, and that unites the various contributions presented in this thesis is how to better inform decision making and guide it towards decisions that will increase the quality (as evaluated both by the engineer and the stakeholders) of the information system being engineered. Topics in two key related areas are therefore addressed. First, boundedly rational individuals cannot take engineering decisions by accounting for all information that may be, or actually is available to them. As their information processing abilities are limited and their perception biased, it is necessary to filter the available information to a manageable level, and to bring it to a format that facilitates the rigorous reasoning invested in decision making. Second, it is necessary to provide guidance on how to use the given information in decision making. The first part of this thesis therefore focuses on conceptualizations that facilitate the identification of relevant information and its organization for subsequent analysis, all in the aim of achieving high quality of the system being engineered. In particular, Part I discusses, shows deficiencies, and accordingly revises the conceptual foundations of requirements engineering, a field of information systems engineering that focuses on the identification and analysis of requirements communicated by the stakeholders to the engineer of the system. The novelty of the suggested revision lies primarily in (i) the separation between functional and nonfunctional (i.e., quality) requirements grounded in a foundational ontology, (ii) the introduction of stakeholders' communicated attitudes as important sources of information for the evaluation of alternative requirements engineering decisions, (iii) the reformulation of the so-called ``requirements problem' -- which precisely defines when the requirements engineering effort is successfully completed -- to account for attitudes and nonfunctional requirements, and (iv) the recognition of the importance of defeasible reasoning in the search for a solution to the requirements problem. Acknowledging the importance of defeasible reasoning leads -- in Part II -- to the study of how defeasible reasoning can be incorporated into established decision making processes involved in the identification and analysis of requirements. Novelty in Part II lies mainly in (i) the use of argumentation and justification processes in the modeling and analysis of requirements, (ii) the combined use of design rationale approaches with argumentation and justification, (iii) the recognition that the clarity of arguments is variable (due to ambiguity, vagueness, synonymy, and overgenerality of information going into premises and conclusions in arguments), (iv) the definition of a number of techniques for the detection of unclear information and its clarification, and (v) the use of ``clarity' as a criterion for the discrimination among arguments. Part III shows how the conceptualizations and techniques introduced in Parts I and II are applied within and are relevant to the engineering of information systems, including those that rely on heterogenous and distributed components, as in service-oriented and agent-oriented computing.

The concepts of processes and services can be used to structure both businesses and software systems. From a business perspective, the use of processes promises efficient management of organizations. From a software perspective, executable process descriptions provide a way to structure software systems according to the business process the systems should support. Furthermore, the concept of software services allows systems to be partitioned in a modular fashion, thereby enabling large-scale system integration on a technical level. By combining process descriptions with software services in service-based processes, it is feasible to address both business and more technical software needs. Aligning the business and software perspectives of processes and software services is, however, challenging, since implemented executable processes and software services need to cater for operational and strategic business needs as well as existing legacy software systems. In this thesis, several instruments are presented that aim at aiding the design and evolution of service-based processes. The aligning of operational business and software perspectives on process descriptions is addressed by the introduction of business and technical process model levels. These levels can be aligned by the use of a set of model transformations and associated transformation rules. Furthermore, the aligning is aided by introducing means for achieving flexibility on both the business and technical model levels. The development of service-based processes from a strategic business point of view is aided by the introduction of novel models and methods for goal-based design of software services. Taken together, the instruments can be used for the design and evolution of service-based processes. / QC 20100810 / REMS / Serviam

L'intérêt va croissant parmi les communautés scientifiques pour le partage de données et d'applications qui facilitent les recherches et l'établissement de collaborations fructueuses. Les domaines interdisciplinaires tels que les neurosciences nécessitent particulièrement de disposer d'une puissance de calcul suffisante pour l'expérimentation à grande échelle. Malgré les progrès réalisés dans la mise en œuvre de telles infrastructures distribuées, de nombreux défis sur l'interopérabilité et le passage à l'échelle ne sont pas complètement résolus. L'évolution permanente des technologies, la complexité intrinsèque des environnements de production et leur faible fiabilité à l'exécution sont autant de facteurs pénalisants. Ce travail porte sur la modélisation et l'implantation d'un environnement orienté services qui permet l'exécution d'applications scientifiques sur des infrastructures de calcul distribué, exploitant leur capacité de calcul haut débit. Le modèle comprend une spécification de description d'interfaces en ligne de commande; un pont entre les architectures orientées services et le calcul globalisé; ainsi que l'utilisation efficace de ressources locales et distantes pour le passage à l'échelle. Une implantation de référence est réalisée pour démontrer la faisabilité de cette approche. Sa pertinence et illustrée dans le contexte de deux projets de recherche dirigés par des campagnes expérimentales de grande ampleur réalisées sur des ressources distribuées. L'environnement développé se substitue aux systèmes existants dont les préoccupations se concentrent souvent sur la seule exécution. Il permet la gestion de codes patrimoniaux en tant que services, prenant en compte leur cycle de vie entier. De plus, l'approche orientée services aide à la conception de flux de calcul scientifique qui sont utilisés en tant que moyen flexible pour décrire des applications composées de services multiples. L'approche proposée est évaluée à la fois qualitativement et quantitativement en utilisant des applications réelles en analyse de neuroimages. Les expériences qualitatives sont basées sur l'optimisation de la spécificité et la sensibilité des outils de segmentation du cerveau utilisés pour traiter des Image par Raisonnance Magnétique de patients atteints de sclérose en plaques. Les expériences quantitative traitent de l'accélération et de la latence mesurées pendant l'exécution d'études longitudinales portant sur la mesure d'atrophie cérébrale chez des patients affectés de la maladie d'Alzheimer.

Researchers in software engineering proposed design method for distributed applications to construct a set of communicating system components from a global behavior. The joint behaviors of these components must precisely satisfy the specified global behavior. The next concern is to transform the constructed models of these components into executable business processes by ensuring the exchange of asynchronous messages among the generated business processes. The introduction of Service-Oriented Architecture (SOA) has helped to achieve this goal. SOA provides high flexibility in composing loosely-integrated services that can be used among business domains to carry out business transactions; this composition is known as service orchestration. Moreover, SOA supports Model Driven Architecture (MDA) such that services modeled as UML Activity Diagrams (AD) can be transformed into a set of Business Execution Language (BPEL) processes. Many researchers discussed the transformation of UML AD and the Business Process Modeling Notation (BPMN) into BPEL. However, they did not discuss the practical limitations that some of these transformations impose. This thesis addresses the imitations of the transformation from UML AD to BPEL processes using the IBM Rational Software Architect (RSA). We showed here that the tool is unable to create the correct BPEL artifacts from UML AD components in certain cases, for instance when the behavior includes the alternative for receiving single or concurrent messages, a weak loop, or certain choice activities. Furthermore, we provided novel solutions to the transformations in these cases in order to facilitate the transformation from UML AD to BPEL.

Pervasive computing is an intuitive evolution of computing paradigms driven by the wide adoption of mobile devices and wireless networks. It introduces a novel way to support users in their everyday life based on open and dynamic environments populated with unobtrusive services able to perform user tasks on the fly. Nevertheless, supporting user tasks from a functional point of view is not enough to gain the user's satisfaction. Users instead require that their tasks meet a certain Quality of Service (QoS) level. QoS is indeed an inherent and primary requisite of users going along with their required tasks. In the context of pervasive environments, fulfilling user tasks while delivering satisfactory QoS brings about several challenges that are mainly due to the openness, dynamics, and limited underlying resources of these environments. These challenges are mainly about (i) the lack of common QoS understanding among users and service providers, (ii) determining and integra- ting, on the fly, the services available in the environment and able to fulfill the functional and QoS requirements of users, and (iii) adapting the provided services at run-time to cope with QoS fluctuations and ensure meeting user requirements. To cope with the aforementioned issues, we opt for a middleware-based solution. Middle- ware represents indeed the appropriate software system to deal with common concerns of user applications such as QoS. In particular, we opt for a specific kind of middleware, viz., Ser- vice Oriented Middleware (SOM). SOM can leverage middleware technologies and the Service Oriented Computing (SOC) paradigm to enable pervasive environments as dynamic service en- vironments. Particularly, SOM can provide middleware services that allow for supporting QoS of user applications offered by pervasive environments. This thesis presents a QoS-aware service-oriented middleware for pervasive environments. The main contributions of this middleware are : (1) a semantic end-to-end QoS model that enables shared understanding of QoS in pervasive environments, (2) an efficient QoS-aware service composition approach allowing to build service compositions able to fulfill the user functional and QoS requirements, and (3) a QoS-driven adaptation approach to cope with QoS fluctuations during the execution of service compositions. The proposed contributions are implemented within a middleware platform called QASOM and their efficiency is validated based on experimental results.

Service Oriented Computing(SOC) is becoming a major paradigm for developing next generation of software systems, and one of the major challenges of Service Oriented Computing is testing interactions and collaborations among the distributed and dynamically integrated web services. To support automated test of web service‟s collaborations, a formal specification is needed. This thesis proposes a specification of web services collaborations based on Web Services Choreography Description Language (WS-CDL). We identify the basic constructs that can be found in any web services collaboration, and we mapped them to the new WS-CDL based language (WS-CDL+). Finally, A scenario of web services collaboration is developed and specification in WS-CDL+ is provided. This work builds a foundation for automated web services testing in a service oriented computing environment.