An Analysis of the Hypertext Versioning Domain

Author:

Jim Whitehead

Email:

ejw-at-cs.ucsc.edu

Advisor:

Richard N. Taylor

Award Date:

2000

Institution:

University of California, Irvine

Institution Location:

California, USA

Web Location:

http://www.soe.ucsc.edu/~ejw/papers/whitehead_diss.pdf

Abstract:

Hypertext captures the implicit and explicit relationships between intellectual works, storing them as data items within the computer, thus allowing them to be navigated, analyzed, and visualized. The evolution of information artifacts such as software development projects, large document collections, and collections of laws and regulations is characterized both by change to the works and their relationships, and the desire to record this change over time. Hypertext versioning is concerned with storing, retrieving, and navigating prior states of a hypertext, and with allowing groups of collaborating authors to develop new states over time.

Several systems provide hypertext versioning services; this dissertation provides a domain model of these systems, comprised of domain terminology, a taxonomy, reference requirements, a data modeling model, and design spaces associated with the requirements. This work offers several significant contributions. It provides a systematic organization of the preponderance of information concerning hypertext versioning systems, including the first taxonomy of such systems, and a comprehensive collection of their requirements. A detailed model of containment is provided; its use highlights that containment is inherent in hypertext systems, and a full understanding of hypertext versioning system data models requires an understanding of their containment relationships. The containment model allows the similarities and differences in hypertext versioning systems to be examined in a consistent manner.

The design space for persistently recording revision histories employs a three-layer model that separates the abstract notion of revision history, shared by all state-based approaches, from the high-level overview of each versioning approach, which is in turn distinct from its specific concrete representation. The design space for link versioning is shown to be an application of the three-layer model for versioning works. Building on the containment model, and the design spaces for versioning works and links, the structure design space concisely describes a range of techniques for recording the history of hypertext structures. Parameters of the structure design space include the abstractions contained within the structure container, the versioning design space choice for each versioned abstraction, the containment choice for each container/containee pair, and the location of any revision selection rules.