Database Systems: A Directed Hypergraph Database: A Model for the Local Loop Telephone Plant

The hypergraph database model was designed and implemented to support an application that deals with the topology of communication circuits, not their transmission properties. The application program inventories, administers, assigns, and assembles the communication circuits connecting the switching entities in the central office to a customer's premises. (See Fig. 1.) (For historical reasons we will use the term "living unit".) The word "loop" in the title refers to such a circuit, while "local" specifies that the loop does not use more than one switching entity. A number of difficult problems arise in modeling the local loop telephone plant. I hope to show that the hypergraph database provides a basis for conceptually clean solutions and that it encourages modularity and information hiding. There are no controlled experiments in a very large project so there is the pain of seeing the large warts in the way "you did it," but no pleasure in knowing how much larger the warts would be if "you had done it the other way". The database described here is a bare bones, do-it-yourself, specially designed version of an entity-relationship database.1 While most of the 2529