Multimedia applications become more dependent on software than hardware. However this dependency reduces the executability of multimedia applications over a various software platforms. Therefore, it is required that a multimedia middleware provides a generic software platform on which necessary set of required Services can be dynamically configured on-the-fly for a given multimedia application. This dynamic configuration can be possible by signaling to the middleware a metadata which contains information about Services for the given multimedia application on a standardized multimedia middleware, which is called MPEG Multimedia Middleware (M3W). In this paper, an open, flexible, and resource-efficient multimedia middleware is designed with a hierarchical model of multimedia Services and metadata schema for supporting a dynamic configuration of the middleware Services so that the necessary set of Services is dynamically configurable in the middleware.