The Amsterdam Hypermedia Model: Adding Time and Context to the Dexter Model

From Computing Reviews, by Jeanine Meyer The purpose of this paper is to convince the reader of the need for a general model for hypermedia and present the Amsterdam hypermedia model (AHM) as fulfilling that need. Hypertext, which is described by the authors as a 'relatively mature discipline,' has the Dexter model, but the authors show that enhancing that model for hypermedia is not a straightforward task. In particular, it requires attention to issues of synchronization. The AHM model includes attention to timing and composite objects as well as implementation issues such as channels and having the sources of components residing over a distributed system. The paper features one example and also describes an authoring and presentation environment called CMIFed. It is generally well written. The paper can be understood even if one has not studied the Dexter hypertext reference model or the CMIF multimedia document model and, in fact, this paper could serve as an introduction to the issues involved. Too much of the focus, however, is on other systems and not on what AHM actually is. The authors do not demonstrate the model by using it to express the featured example. Moreover, to really merit the term 'model,' AHM should be shown as serving a substantial role in describing and implementing applications in terms of two or more distinct authoring or runtime environments. This is not done, though it appears well within the experience and understanding of the authors.