With the proliferation of multimedia data sources on the Internet, we envision an increasing demand for value-added and functionrich multimedia services that transport, process, and analyze multimedia data on behalf of end users. More importantly, multimedia services are expected to be easily accessible and composable by users. In this paper, we propose MSODA, a service-oriented platform that hosts a wide spectrum of media services provided by different parties. From the user’s point of view, MSODA is a shared “market” for media service access and composition. For a media service provider, MSODA creates a virtual dedicated environment for service deployment and management. Finally, the underlying MSODA middleware performs the key functions of service composition, configuration, and mapping for users. We discuss key challenges in the design of MSODA and present preliminary results towards its full realization. Categories and Subject Descriptors C.2.5 [Computer-Communication Netw...