Résumé
This thesis deals with dynamic service exchange modelling. The notion of service is now at the centre of distributed system development; it plays a key role in their implementation and success. The thesis proposes firstly a reflection about the notion of service and introduces the concept of Dynamic Service Generation (DSG) as a different way to provide and use services in a computer-mediated context: services are dynamically constructed, provided and used by agents (human or artificial) within a community, by means of a conversation. In particular, two major characteristics of DSG are highlighted: an agent and Grid oriented aspect of service exchange. Therefore, the thesis proposes an integration of three research domains in Informatics: Service-Oriented Computing (SOC), Multi-Agents System (MAS) and GRID. The thesis contributions consists of three main aspects: The proposal of (i) a new agent representation and communication model, called STROBE, that enables agents to develop different languages for each agent they communicate with. STROBE agents are able to interpret communication messages and execute services in a given dynamic dedicated conversation context; (ii) a computational abstraction, called i-dialogue (intertwined dialogues) that models multi-agent conversations by means of fundamental constructs of applicative/functional languages (i.e., streams, lazy evaluation and higher-order functions); (iii) a service-oriented GRID-MAS integrated model based on the representation of agent capabilities as Grid services. In this model, concepts of GRID and MAS, relations between them and the rules are semantically described by a set-theory formalization and a common graphical description language, called Agent-Grid Integration Language (AGIL). AGIL integrates the thesis results together by formalizing agent interactions for service exchange on the Grid.