1993cikm R.J. Peters, A. Lipka, M.T. Özsu and D. Szafron, An Extensible Query Model and Its Languages for a Uniform Behavioral Object Management System, CIKM 93, Washington, D.C., November 1993, pp. 403-412. abstract or pdf.

In this paper, we present an extensible, uniform, behavioral query model and its languages for the TIGUKAT object management system. The TIGUKAT model is purely behavioral in nature, supports full encapsulation of objects, defines a clear separation between primitive components such as types, classes, collections, behaviors, functions, etc., and incorporates a uniform semantics over objects which makes it a favorable basis for a query model. Queries are modeled as type and behavior extensions to the base object model, thus incorporating queries as an extensible part of the model itself. We present the framework of the complete query model definition that includes the extended types and behaviors, a formal object calculus with safety based on the evaluable class of queries, an equivalent object algebra, an SQL-like ad hoc query language for user-level querying and proof of its completeness.