Tecnologías middleware para el desarrollo de servicios en entornos de computación ubicua

En esta Tesis doctoral realizamos contribuciones en el campo de la definición de tecnologías middleware para el desarrollo de servicios en entornos de computación ubicua. En primer lugar, abordamos el problema del descubrimiento de servicios, que permitirá que de forma automática un dispositivo descubra los servicios ofrecidos por otros dispositivos que le rodean. Aunque existen propuestas en este sentido, no cubren todas las necesidades que imponen estos nuevos entornos de computación, por lo que hemos definidio un nuevo mecanismo de descubrimiento: Pervasive Discovery Protocol (PDP). En sengudo lugar, proponemos el uso de la tecnología de agentes móviles como middleware para el desarrollo de servicios en entornos ubicuos. Los agentes se caracterizan por estar orientados a realizar tareas, por ser autónomos, por su capacidad de cooperar y si poseen la característica de movilidad, por ser capaces de moverse a sistemas remotos para realizar sus tareas, minimizando el coste de las comunicaciones. Estas características se adaptan a las restricciones que imponen la computación ubicua. En esta línea, contribuimos a la adaptación del estándar de agentes FIPA para su funcionamiento en estos entornos, y en concreto, nos centramos en el Directory Faciliator (DF). Estas propuestas nos han llevado a participar de forma activa en el comité técnico FIPA Ad-Hoc. _________________________________________________In this Ph.D. dissertation, we contribute to the definition of middleware technologies for the development of services in pervasive computing environments. First, we broach the problem of service discovery, that allow devices to automatically discover the services offered by other devices in their surroundings. Although other proposais exist, we think none of them fulfils the needs of these new environments, so we have defined a new discovery mechanism: the Pervasive Discovery Protocol (PDP). PDP is a new protocol designed for local scopes, fully distributed, where requests and replys are both multica,sted, and where each device stores in a local cache the advertisements listened so far and shares this information with the devices arround it. PDP manages to reduce the number of messages transmited per service request while obtaining high service discovery ratios, and besides it makes devices with greater availability time to answer flrst, so minimizing the battery dram of the more power-constrained ones. Secondly, we propose the use of mobile agents technology as the middleware for the development of services in a pervasive computing nvironment. Agents are characterized by their autonomous and goal-oriented behaviour, their ability to cooperate with other agents and, if mobile, they are able to move to remote systems to carry out their task, so minimizing the communication cost. These characteristics fit well into the restrictions that pervasive computing impose. We also aim to adapt the FIPA standard to these environments; specifically, we concentrate in the yellow pages service, the so called Directory Facilitator (DF). In our solution, we define a new agent, the Service Discovery Agent (SDA), that uses an underlaying implementation of our service discovery protocol, PDP, to make efficient searches of remote services, removing the mechanism of DFs federation defined by FIPA. These proposais have been presented and discussed in the FIPA Ad-Hoc Technical Commitee, after what we were invited to take part and are now an active member of it