Under CoVer: the implementation of a contextual version server for hypertext applications

At GMD-IPSI we are developing CoVer, a contextual version server for hypertext applications. Another characterization of CoVer is that CoVer integrates state-oriented versioning concepts with task-oriented versioning concepts. While other version models in general support only one of these groups of concepts, we argue that the explicit composition of versions of complex hypertext networks has to be complemented by automatic version creation in the context of tasks or jobs performed while manipulating the hypertext network and vice versa. Regarding the implementation of version models, it turns out that the state-oriented implementation approach—representing every legal state of a hyperdocument explicitly—and the task-oriented implementation approach—computing versions of complex hypertext networks due to changes executed during a task or job—are interchangeable. While the separation of state- and task-oriented concepts at the conceptual level of the version model is desireable to support version creation and selection for different hypertext applications, the implementation of such a dual model can be based on a single implementation approach. This paper discusses both types of implementation with an emphasis to cope with alternative versions that are in particular meaningful for hypertext publishing applications.