Requirements Document for the UNC Distributed Graph Service TR 91 - 051 December , 1991

A distributed hypermedia storage service--called the UNC Distributed Graph Service (DGS)--will become the database for a hypermedia computer-supported, cooperative work environment called ABC. The DGS data model has been designed to support the unique storage needs of users who are collaborating to solve complex problems. Since it is based on the formalism of directed graphs, the DGS data model provides a structured method for organizing and relating the diverse materials that collaboration produces. In our discussion, we will first enumerate the special requirements that a collaborative environment places on a database and then describe specific mechanisms for satisfying those requirements in the DGS data model. A number of research issues are raised, including: partitioning and structuring the materials produced by collaboration; distinguishing between public and private views of information; providing an extensible, open architecture for applications; representing fine-grained associations using anchored hyperlinks; providing appropriate concurrent access to information; and maintaining the integrity, consistency, and completeness of the database as a whole.