An abstract layered model for hypermedia document system
We propose a layered model for hypermedia document systems and use this model in the design and implementation of a prototype hypermedia document system. The model consists of three layers: a runtime layer (RTL) a document description layer (DOCDL) and a storage layer (SRL). The DOCDL contributes to defining the logical structure. It not only constrains the structure of the SRL, but also forms a bridge between the RTL and the SRL. In the DOCDL, an extended open document architecture (ODA) is employed for describing the logical structure of the document. In addition, we present a technique for automatically generating and updating database schema given a document logical structure. For the RTL, the document logical structure is visualized to help users to retrieve information, and as a means for multimedia data capture. The advantages and benefits of this approach are to allow the design and implementation of hypermedia systems to be automated and much simplified. The approach also caters for the continuous updating of the document logical structure such as adding an extra data object. The paper applies the proposed model to the design and implementation of a multimedia document system for medical documents.