With the increasing use of small portable devices and wireless networks, a trend to support computing on the move has emerged.This trend is referred to as 'anytime/anywhere computing' for mobility support.In particular, multimedia service with heterogeneous devices, location-free access and user-context awareness is still a very active and evolving field of research in broad areas.In this paper, a movable multimedia framework, namely UMOST(Ubiquitous Middleware Of Streaming Technology), is proposed for multimedia session mobility.It provides various levels of quality of service management, as well as seamless user-level handoffs using MPEG-21 Digital Item Adaptation(DIA). It serves scalable streaming adaptive to the user, and deploys a back-end content distribution network for adapting dynamically to environmental changes through prefetching.The implemented framework employs a smart space aimed at demonstrating the feasibility of multimedia session mobility.