Service Selection Based on Non-functional Properties

Service-oriented Architecture supports software to be composed from services dynamically. Selecting and composing appropriate services according to business process, policies and non-functional constraints is an essential challenge. This paper proposes a method for automatic selection of the most relevant service for composition based on non-functional properties and the user’s context. In doing this we also propose a method of obtaining and evaluating non-functional aspects

A Four-Level Linear Discriminant Analysis Based Service Selection in the Cloud Environment

The cloud is an outstanding platform to deal with functionally equivalent services which are exponentially increasing day-by-day. The selection of services to meet the client requirements is a subtle task. The services can be selected by ranking all the candidate services using their network and non-network Quality-of-Service (QoS) parameters, which is formulated as a NP hard optimization problem. In this paper, we proposed a linear discriminant analysis (LDA) based a four level matching model for service selection based on QoS parameters, which includes description matching of a service, matchmaking phase, LDA-based QoS matching and ranking. The LDA-service selection agent is deployed on each cloud to classify services into classes and rank the services based on the aggregate QoS value of each service. Finally, the test results show the efficiency in service selection with minimal discovery overhead, significant reduction in the computation time and the number of candidate services to be considered

Monitoring the quality of service to support the service based system lifecycle

Service Oriented Computing (SOC) has been established in the last recent years as a successful paradigm in Software Engineering. The systems built under this paradigm, known as Service Based System (SBS), are composed of several services, which are usually third-party software run by external service providers. SBS rely on these service providers to ensure that their services comply with the agreed Quality of Service (QoS). In contrast to other systems, the dynamic behaviour of SBS requires up-to-date QoS information for its proper management in the different stages of its lifecycle, from their initial construction until their decommission. Providing such QoS information has resulted in different technological solutions built around a monitor. Nonetheless, several research challenges in the field remain still open, ranging from theoretical aspects of quality assurance to architectonical challenges in decentralized monitoring. Based on the current research challenges for service monitoring, the research gaps in which we aim to contribute are twofold: - To investigate on the definition and structure of the different quality factors of services, and provide a framework of common understanding for the definition of what to monitor. - To investigate on the different features required to support the activities of the whole SBS lifecycle (i.e. how to monitor), and develop a monitoring framework that accomplishes such features. As a result of this thesis, we provide: What to monitor - A distribution of the quality models along the time dimension and the identification of their relationships. - An analysis of the size and definition coverage of the proposed quality models. - A quantified coverage of the different ISO/IEC 25010 quality factors given by the proposals. - The identification of the most used quality factors, and provided the most consolidated definitions for them. How to monitor - The elicitation of the requirements of the different activities in the SBS lifecycle. - The definition of the set of features that supports the elicited requirements. - A modular service-oriented monitoring framework, named SALMon, implementing the defined features. SALMon has been validated by including it in several frameworks supporting the different activities of the SBS lifecycle. Finally, we have conducted a performance evaluation of SALMon over real web services.La Computació Orientada a Serveis (SOC) ha esdevingut en els darrers anys un paradigma exitós en el camp de l'Enginyeria del Software. Els sistemes construïts sota aquest paradigma, coneguts com Sistemes Basats en Serveis (SBS), estan composats de diversos serveis, que són, usualment, programari de tercers executats per proveïdors de serveis externs. Els SBS depenen dels proveïdors dels serveis per garantir que els serveis compleixen amb la Qualitat del Servei (QoS) acordada. En contrast amb altres sistemes, el comportament dinàmic dels SBS requereix d'informació actualitzada del QoS per a la correcta administració de les diferents etapes del cicle de vida dels SBS: des de la seva construcció inicial fins a la seva clausura. Proveir d'aquesta informació de QoS ha resultat en diferents solucions tecnològiques construïdes al voltant d'un monitor. Malgrat això, diversos reptes de recerca en el camp encara romanen obertes, des d'aspectes teòrics de l'assegurança de qualitat, a reptes arquitectònics en la monitorització descentralitzada. Basat en els reptes de recerca actuals per a la monitorització de serveis, els forats de recerca en els que pretenem contribuir són dobles: - Investigar en la definició i estructura dels diferents factors de qualitat dels serveis, i proveir un marc de treball d'entesa comuna per a la definició de què monitoritzar. - Investigar en les diferents característiques requerides per donar suport a les activitats de tot el cicle de vida dels SBS (i.e. com monitoritzar), i desenvolupar una plataforma de monitorització que acompleixi aquestes característiques. Com a resultats de la tesis, proveïm: Què monitoritzar - Una distribució dels models de qualitat al llarg de la dimensió temporal i la identificació de les seves interrelacions. - Un anàlisi de la mida i definició de la cobertura dels models de qualitat proposats. - Una cobertura quantificada dels diferents factors de qualitat ISO/IEC 25010 donat en les diferents propostes. - La identificació dels factors de qualitat més utilitzats, i la definició dels termes més consolidats. Com monitoritzar - L'elicitació dels requeriments per a les diferents activitats en el cicle de vida dels SBS. - La definició del conjunt de característiques que donen suport als requeriments elicitats. - Una platforma modular orientada a serveis, anomenat SALMon, que implementa les característiques definides. SALMon ha estatvalidat incloent la plataforma en diversos marcs de treball donant suport a les diferents activitat

QoS awareness support in Web-Service semantics

Web Services (WSs) are a new breed of web application that have brought out quite challenging research issues. One of these is the establishment of an interoperable semantic framework suitable to represent all potential features of WSs. Apart from the functional properties that have already been modeled via standardized tools, there are also the nonfunctional features of WSs i.e. their Quality-of-Service, which in most cases are not included in the WS description. Nevertheless, integrating QoS features in WS profiles is to the advantage of both users and providers, as it supports QoS-aware WS selection and composition addressing the user’s QoS requirements, while enabling WS providers to increase their profit in the e-business domain. This paper is concerned with the creation of a QoS ontology framework adequate for WS provision. It has sprang from the work carried ou