An Ada-compatible distributed database management system

Adaplex is an integrated language for programming database applications. It results from the embedding of the database sublanguage Daplex in the general-purpose programming language Ada [1]. This paper describes the design of DDM, a general-purpose distributed database management system implemented in Ada that supports the use of Adaplex as interface language. There are two novel aspects in the design of this system. First, this is the first full-scale distributed database system to support a semantically rich, functional data model. DDM goes beyond systems like Distributed INGRES and R^*(which are based on the relational technology) in providing advanced data modeling capabilities and ease of use. Second, this is the first full-function distributed DBMS designed to be compatible with the Ada programming environment. The coupling between Ada and Daplex has been achieved at the expression level which is much tighter than the statement level integration attained in previous systems. This tight coupling poses new implementation problems but also creates new opportunities for optimization. The current paper highlights the Adaplex language and discusses innovative aspects in DDM´s design that are intended to meet the dual objectives of good performance and high data availability.