Quality of service support for service discovery and selection in service oriented computing environment

Service oriented computing (SOC) represents a new generation of web architecture. Central to SOC is the notion of services, which are self-contained, self-describing, modular applications that can be published, located, and invoked across the Internet. The services represent capability, which can be anything from simple operations to complicated business processes. This new architecture offers great potential for e-commerce applications, where software agents can automatically find and select the services that best serve a consumer's interests. Many techniques have been proposed for discovery and selection of services, most of which have been constructed without a formal Quality of Service (QoS) model or much regard to understanding the needs of consumers. This thesis aims to provide QoS support for the entire SOC life cycle, namely: (i) extend current approaches to service discovery that allow service providers to advertise their services in a format that supports quality specifications, and allows service consumers to request services by stating required quality levels, (ii) support matchmaking between advertised and requested services based on functional as well as quality requirements, (iii) perform QoS assessment to support consumers in service selection. Many techniques exists for performing QoS assessment, most of which are based on collecting quality ratings from the users of a service. This thesis argues that collecting quality ratings alone from the users is not sufficient for deriving a reliable and accurate quality measure for a service. This is because different users often have different expectations and judgements on the quality of a service and their ratings tend to be closely related to these expectations, i.e., how their expectations are met. The thesis proposes a new model for QoS assessment, based on user expectations that collects expectations as well as ratings from the users of a service, then calculates the QoS using only the ratings which were judged on similar expectations.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Quality of service support for service discovery and selection in service oriented computing environment

Service oriented computing (SOC) represents a new generation of web architecture. Central to SOC is the notion of services, which are self-contained, self-describing, modular applications that can be published, located, and invoked across the Internet. The services represent capability, which can be anything from simple operations to complicated business processes. This new architecture offers great potential for e-commerce applications, where software agents can automatically find and select the services that best serve a consumer's interests. Many techniques have been proposed for discovery and selection of services, most of which have been constructed without a formal Quality of Service (QoS) model or much regard to understanding the needs of consumers. This thesis aims to provide QoS support for the entire SOC life cycle, namely: (i) extend current approaches to service discovery that allow service providers to advertise their services in a format that supports quality specifications, and allows service consumers to request services by stating required quality levels, (ii) support matchmaking between advertised and requested services based on functional as well as quality requirements, (iii) perform QoS assessment to support consumers in service selection. Many techniques exists for performing QoS assessment, most of which are based on collecting quality ratings from the users of a service. This thesis argues that collecting quality ratings alone from the users is not sufficient for deriving a reliable and accurate quality measure for a service. This is because different users often have different expectations and judgements on the quality of a service and their ratings tend to be closely related to these expectations, i.e., how their expectations are met. The thesis proposes a new model for QoS assessment, based on user expectations that collects expectations as well as ratings from the users of a service, then calculates the QoS using only the ratings which were judged on similar expectations

Modelo de planificación y ejecución concurrente para la composición de servicios web semánticos en entornos parcialmente observables

Los servicios Web (SW) son componentes de software que pueden ser expuestos sobre Internet e invocados a través de protocolos estándar. Incorporar semánticas a los SW, tiene como objetivo describir los aspectos semánticos, además de los sintácticos de los propios servicios. Tales descripciones permiten a los componentes de software interactuar automáticamente a fin de lograr determinadas tareas sobre los servicios, entre las que se destaca la composición de servicios en servicios más complejos. Grandes esfuerzos se realizan en este campo de la composición, pero a pesar de lo exitosas que puedan ser las aproximaciones planteadas a la fecha, aún se caracterizan por no enfrentar conjuntamente algunos factores inherentes a la Web: el ser un entorno parcialmente observable, el comportamiento incierto de los servicios y las restricciones de tiempo en las respuestas de composición. Un promisorio enfoque orientado a este fin, es el liderado por la comunidad de la Inteligencia Artificial (IA), la cual enfrenta la composición de servicios Web mediante la aplicación de técnicas de planificación IA. Es así como en este trabajo de tesis de doctorado, se propone un modelo que permita llevar a cabo la composición automática de Servicios Web Semánticos (SWS), integrando concurrentemente procesos de planificación y ejecución con restricciones de tiempo. De esta forma, se adquiere progresivamente solo la información esencialmente requerida del estado actual de la Web limitando la respuesta (un plan de composición), a un período de tiempo especificado, superando conjuntamente, dificultades propias del dominio del problema como las antes mencionadas. / Abstract. Web Services (WS) can be defined as software components that can be exposed and called on the Internet using standard communication protocols. To include semantic mechanisms in WS is aim at describing semantics aspects of the services as well as syntactic ones. Such kinds of descriptions allow software components automatically interact in order to achieve certain tasks applied on services, among which, it should be highlighted the composition of services to obtain more complex services. Great efforts have already being made within the WS composition field, but in spite of those successful approaches that can be raised to date; they are still characterized for being unaware of some key issues inherent to the Web: the fact to be a partially observable environment, the services’ uncertain behavior, and time constraints related to WS composition responses. A promising approach aimed at this purpose is headed by the Artificial Intelligence (AI) community that faces the WS composition based on the application of AI planning techniques. Thus, in this doctoral thesis dissertation, a model to perform the automatic composition of Semantic Web Services (SWS) is proposed which concurrently integrates AI planning and execution processes under time constraints. In this way, this model gradually acquires only the required essential information of the Web’s current state, and restricts the response (a composition plan) to a given time period, overcoming together, those difficulties inherent to the problem domain as mentioned above.Maestrí