Auerbach Publications © 2004

This chapter describes the architecture and components of distributed Multimedia Database Systems (MMDBMS) responsible for delivering, streaming, and receiving multimedia data, and the effect of MPEG-21 on the implementation of the components is described in particular. We will start by illustrating different distributed MMDBMS architectures in use; namely, the client-server (C-S), peer-to-peer, and an MPEG-21-based architecture. The remaining parts of this chapter are mainly the descriptions of the different components: multimedia storage servers, network and client considerations, and finally, adaptation issues. 5.1 Architectural Considerations 5.1.1 C-S System Many distributed MMDBMSs [1], [2] for pull applications rely on C-S architectures. In this scenario, client applications request multimedia data from the server, which are then processed locally. Obviously, this architecture minimizes the degree of parallel processing that can occur because of the synchronous nature of the request function. [3] Furthermore, it is a common experience that pure C-S systems do not scale well with respect to the number of users, the heterogeneity of the terminals employed, and the size of the data requested. Exhibits 5.1 and 5.2 give an example in which two media storage and streaming servers are available for media requests. The three terminals here support, because of their hardware characteristics, three different coding standards—MPEG-4 Simple, Core, and Complex—and different display capabilities. Moreover, the network between the server and the terminal differs, as the personal computer (PC) in the example has a direct and good connection via LAN (local area network) to the Internet and the mobile phone must go over a mobile network. Exhibit 5.1: Client-server-based multimedia system