Treffer: Typed Declarative Object-Oriented Database Programming

Extending a strongly typed object-oriented programming language system technology to an object-oriented database technology requires a high-level, object-oriented specification language that would perform the role of a query language in classical database technologies (for example, the relational one). Our goal is to design and implement such a specification language as a semantic extension of an advanced, polymorphic, object-oriented database type system, so that procedural specification of methods will be abandoned whenever possible. A variety of logic paradigms have been explored in the literature as candidates for the formal basis of such a language (O-logic, F-logic, Horn-clause logic with equality and its extensions, the rewriting logic). Our contribution is in demonstrating that an appropriately defined temporal logic tied with an advanced object-oriented type system is better suited than any of the other candidates for expressing complex behavioral properties of objects and state transitions in particular. On the implementation side of the issue, we demonstrate that our specifications are effectively executable. This observation leads to a prototyping tool as a powerful assistant in designing complex objectoriented systems in strongly typed manner, allowing complex design decisions to be tested structurally and behaviorally prior to the major implementation efforts.