The Tower Model

At the fourth ACM Conference on Hypertext, P. De Bra, G.J. Houben and Y. Kornatzky proposed a new, object oriented, extensible data model for hyperdocuments.

The model contains basic structural elements such as nodes, links, anchors, tower objects and city objects. Descriptions of an object is modeled with the tower object, therefore, type, structure of the storage system, presentation system, etc. are levels of the tower object. City object represents set of views to the tower objects. The tower objects are used to model different descriptions of an object, similar like the layers in the Dexter model.

The model allows every kind of object to be a virtual object (i.e. the result of a function or algorithm). Operators for defining virtual structures are Apply-to-All, Filter, Enumeration and Abstraction (or grouping).