The Data Model of the Abc Distributed Graph Storage System Tr93-012

Our project is studying the process by which groups of individuals work together to build large, complex structures of ideas and is developing a distributed hypermedia collaboration environment (called ABC) to support that process. This paper focuses on the data model of the Distributed Graph Storage (DGS) component of ABC. The DGS supports a graph-based data model, conservatively extended to meet hypermedia requirements. Since the data model conforms closely to the graph-theoretic notion of directed graphs, it provides a structured method for organizing and relating the diverse materials that collaboration produces. Central concepts such as node, link, and aggregate are derived from the graph metaphor rather than by ad-hoc de nition. As a result, the model strikes a healthy balance between arbitrary exibility and consistent structure.