Among the commercial object-oriented database management systems, O2 is a system that in fact has linguistic reflective capabilities of the sort required by Java OQL [Bancilhon et al.

NAOS: Efficient and modular reactive capabilities in an object-oriented database system.

MOSAICO--A system for conceptual modeling and rapid prototyping of object-oriented database applications.

A comparison of object-oriented database management systems for engineering applications.

This seemingly oxymoronic task is actually quite possible, as recently demonstrated by the commercial availability of UniSQL, Inc.'s (Austin, Tex.) unified relational and object-oriented database system, UniSQL/X, the UniSQL/X database system supports the SQL/X query language which has been developed by extending ANSI Structured Query Language (DDL, DML & Query, and DCL) with natural support for classes, objects, arbitrary data types, methods, complex nested data structures, and multiple inheritance.

Intermedia: A case study of the differences between relational and object-oriented database systems.

"One of the advantages of an object-oriented database is that is makes it very easy for us to do that kind of incremental checking," he says.

In ADvances in Object-Oriented Database Systems, K.

The [O.sub.2] system is an object-oriented database management system (OODBMS) with a complete development environment and a set of user interface tools.

ObjectStore is an object-oriented database management system (OODBMS) that provides a tightly integrated language interface to the traditional DBMS features of persistent storage, transaction management (concurrency control and recovery), distributed data access, and associative queries.

GemStone visual schema designer: A tool for object-oriented database design IFIP TC 2.6 Working Conference on Object Oriented Databases: Analysis, Design, and Construction, Windemere, United Kingdom, July 1990.

As well shall soon see, sharing subobjects is not precluded by value-based relational DBMSs, as claimed by the "Object-Oriented Database System Manifesto" [5] (7).

Ferrie, "Integrating Concurrency Control into an Object-Oriented Database System," in Proc.

Object-oriented database, however, is the relatively new technology, it is lack of theoretical support, he may have in dealing with a large number of data contains a lot of affairs much more slowly than a relational database system, but people have developed a hybrid object database, the database will be a relational database management system's ability to deal with affairs and object-oriented database systems dealing with the complex relationships and the ability of the new data.