AHA! An open Adaptive Hypermedia Architecture

Hypermedia applications generate comprehension and orientation problems due to their rich link structure. Adaptive hypermedia tries to alleviate these problems by ensuring that the links that are offered and the content of the information pages are adapted to each individual user. This is done by maintaining a user model. Most adaptive hypermedia systems are aimed at one specific application. They provide an engine for maintaining the user model and for adapting content and link structure. They use a fixed screen layout that may include windows (HTML frames) for an annotated table of contents, an overview of known or missing knowledge, etc. Such systems are typically closed and difficult to reuse for very different applications. We present AHA, an open Adaptive Hypermedia Architecture that is suitable for many different applications. This paper concentrates on the adaptive hypermedia engine, which maintains the user model and which filters content pages and link structures accordingly. The engine offers adaptive content through conditional inclusion of fragments. Its adaptive linking can be configured to be either link annotation or link hiding. Even link disabling can be achieved through a combination of content and link adaptation. We provide three examples of different applications that are all based on the same engine: an adaptable course text where full text and viewgraphs are integrated, a fully adaptive course on the subject of hypermedia (using a simple presentation without HTML frames) and a “kiosk” information system (with frames and JavaScript).