Especificação formal da atividade de negociação em serviços semânticos.

Abstract

The rise of semantic services and their use has been the subject of intense research in recent years. In this context, ontologies are used as structures of knowledge representation, to facilitate reuse and sharing of information However, the multiplicity in the semantic description of services, difficulty in reaching consensus on the definition of domain ontologies and the use of different perspectives present an obstacle to automate service related tasks. Service provision consists on a complex process, composed of several subactivities, such as publication, discovery, negotiation, selection, composition, execution and monitoring However, the work accomplished was focused on the discovery, negotiation, selection and service monitoring phases. Aiming to achieve a better understanding of the questions raised from each one of the phases, a study based on the music industry was conducted. A survey of service conditions indicates the need of using new business models and new strategies that may enable the customization of services, giving users a more active role in the process. To deal with the drawbacks found in the service oriented scenario, an integrated approach was used, that unites two models: one, focused on user perception and the other focused on the service provision phases. The models used in the integrated approach are Escher and Persona;, respectively. The resulting model of this approach was named extended model, and it unites the expressiveness of Escher to the service provisioning phases addressed in Persona;. Acknowledging that the model Persona; addresses the initial phases in the service provisioning lifecycle, the phases of negotiation, monitoring and contracts re-negotiation were added to the extended model. The presented approach, named the integrated approach, enabled to perceive that the main concepts related to the service provisioning domain were addressed. The use of two scenarios to illustrate the applicability of the extended model was effective to demonstrate the capability of the model to meet the needs of either kind of user, a nonexpert and an expert user, on the tasks related to service provisioning on the web.