The main UC3M objective in Opium is to assess the effectiveness of active middleware services in the context of a real UMTS network, in particular, in the Spanish network platform. In other words, Opium will provide specific insight and knowledge on the value added by the deployment of intelligent IP devices (active nodes) as near as possible to the UMTS terminals. The fundamental purpose of these devices is running applications inside the network to improve the performance of TCP/IP end user applications and UMTS cell bandwidth usage, as these factors are strongly constrained by the special characteristics of the terminals (memory size, computing capacity, autonomy) and the radio segment (bandwidth, BER, off-coverage periods). In principle, active entities can boost the quality of the service perceived by the users if they are able to behave on behalf of the user at either transport (typically TCP splitting or spoofing) or application level (content caching and pre-fetching). This objective is paramount not only to the final look-and-feel of the services demonstrated by Opium but also has the added-value of being a novel approach that could open new possibilities and applications during the development of the project. The target middleware platform to demonstrate these network processes is SARA, described in section 2.2. Its ability to dynamically load code and to intercept/process any packet flow will be used to ease the management of the applications integrated and demonstrated in Opium trials.