The well system: A multi-user database system based on binary relationships and graph-pattern-matching

摘要

The WELL database system is based on the WEB-model, a binary data model in which entities and their relationships are described by graph-like data structures with labelled nodes and edges. These data structures together with a changeable schema provide a high degree of data independence, flexibility and evolvability. A powerful graph-pattern-matching technique is used for accessing and manipulating the database. In this paper the host-language interface (for PL/I) and its underlying concepts of the WELL system are described. With the help of this interface an application programmer can easily construct terminal interfaces for non-programmers. As the WELL system supports simultaneously working users, solutions for authentication and concurrency of updates are integrated in its design.