Gema: a nested relations applications generator

Gema, Generator of Multiple Applications is a system for the evolutionary prototyping of interactive database applications. Gema uses direct-manipulation interfaces for the specification of nested relational database schemas, views, forms, menus, reports and applications structure. User procedures can be attached at several places as the desired application evolves from a simple prototype to its finished form. Procedures can be coded using Gema's database programming language (DBP2). Also, applications specified graphically can be translated to Gema's DBPL. The authors describe Gema and its DBPL, which is an extension of Pascal, that includes facilities to manage nested relations, handles persistence of any type of variable, and has procedures as first-class objects.<>