A Grid-based architecture for Multimedia services management

The current client server computational model assumes to know where computing and storage power are located. As imposed from the current technological evolution, as well as from the continuously increasing users requirements, it is widely recognized that such a model has to evolve in order to transparently access distributed computing and storage resources, showing the final results directly on the user terminal. Thus it is mandatory to develop a middleware layer that will mediate and manage the access to the distributed resources. Grid technology [7] [6] is a new paradigm which has the potential to completely change the way of computing and data access. Although there is no widely agreed definition what Grid means, the consequences for scientific and research work, but also for the private users, will be severe. Computational Grids are widely regarded as the next logical step in computing infrastructure, following a path from standalone systems, to tightly linked clusters, to enterprise-wide clusters, to geographically dispersed computing environments. Generally speaking, we could consider the Grid as the new enabling technology to transparently access computing and storage resources anywhere, anytime and with guaranteed Quality of Service (QoS). Although still in its infancy, Grid is already being successfully used in many scientific applications where huges amounts of data have to be processed and/or stored. Some examples include the processing of data coming from physic-related applications, like the data generated in the nuclear accelerator of CERN [1], the data coming from radio telescopes, the data generated in complex simulations [2] and so on. There is no doubt that such demanding applications have created, justified and diffused the concept of Grid among the scientific community, but as a matter of fact such powerful technology is still confined to a very restricted scientific environment. We do think that the time is right for the Grid to reveal its potentialities to a wider audience, which is mainly constituted of users with every day problems and requirements. Obviously such needs cannot directly compete with the highly demanding scientific applications described so far, but, as the amount of potential users is really enormous, the accumulated data processing and storage requirements are at least comparable. One of the possible new application fields for the Grid Computing is the management of multimedia services in wireless environments. In fact the current tendency is to allow mobile users to access