Opening Up Hypermedia

1. Introduction Important goals for hypermedia information systems are that users, independent of their geographical location, can be given coordinated on-line access to material that is contained in multiple information databases, that they can later (re-)use extracts from the material already displayed, and that the other applications they use can also interact with the information. In other words, a hypermedia system needs to be open with respect to: • information — the same presentation 1 can be displayed by heterogeneous end-user systems; • data — pre-created media objects can be (re-)used in multiple presentations; • other applications — the hypermedia presentation environment can exchange data and/or messages with other applications. We discuss each of these categories in turn, but first look at the basic components of an open hypermedia environment. An intuitive overview is given in Fig. 1. Here, the basic components are the user's information need, an end-user environment, an information source, and the creator of the information. Any of these can be multiple, and exist in