SPS-ALGOL: Semantic constructs in a persistent programming language

Persistent data is defined as that which survives on secon­dary store after program execution terminates. In a persistent programming language there is no distinction what ­ever between persistent data and other objects. In contrast to conventional systems, both the data structures and the operations applicable to " permanent " data are identical to those used for short- term data. PS -Algol is the only implemented persistent language at present. This paper describes a proposed extension to this language, SPS-Algol, which incorporates more of the concepts and tools of databases and semantic data models. In particular transactions, tasks, type hierarchies, association, data derivation, semantic integrity constraints and subschemas are proposed as useful extensions to the programming language, and some of the implementation issues involved are discussed