Hong-Tai Chou

Composite object support in an object-oriented database system

Many applications in such domains as computer-aided design require the capability to define, store and retrieve as a single unit a collection of related objects known as a composite object. A composite object explicitly captures and enforces the IS-PART-OF integrity constraint between child and parent pairs of objects in a hierarchical collection of objects. Further, it can be used as a unit of storage and retrieval to enhance the performance of a database system. This paper provides a formal definition of the semantics of composite objects within an object-oriented data model, and describes their use as units of integrity control, storage and retrieval, and concurrency control in a prototype object-oriented database system we have implemented.

Versions and change notification in an object-oriented database system

The authors have built a prototype object-oriented database system called ORION to support applications from the CAD/CAM (computer-aided-design/computer-aided-manufacturing), AI (artificial-intelligence), and office-information-system domains. Advanced functions supported in ORION include versions, change notification, composite objects, dynamic schema evolution, and multimedia data. The versions and change notification features are based on a model that the authors developed earlier. They have integrated their model of versions and change notification into the ORION object-oriented data model, and also provide an insight into system overhead that versions and change notification incur.<<ETX>>

Object-oriented database support for CAD

Abstract ORION is a prototype object-oriented database system built in the Advanced Computer Technology (ACT) Program at MCC. It is intended to support the data management needs of applications in such domains as computer-aided design, artificial intelligence, and office information systems. The paper describes features of ORION which have been implemented specifically to support CAD environments. These include dynamic schema evolution, version control and change notification, and transaction management.

Operations and implementation of complex objects

Many applications in the CAD/CAM and AI domains require the capability to define and manipulate a structured collection of records as a single logical entity, called a complex object. A complex object is the unit of sharing among many configurations of higher level entities. In this paper, we present a model of complex object and define a set of meaningful operations, both basic and advanced, on a single complex object and on a configuration of complex objects. We then present a set of requirements for storage subsystems that support complex objects. We also describe our implementation of complex objects and operations on a single complex object; and provide a detailed performance analysis which establishes the merit of complex objects. Finally, we propose storage techniques for supporting advanced operations on a configuration of complex objects.

Enhancing the object-oriented concepts for database support

In this paper, we elaborate on three major enhancements to the conventional object-oriented data model, namely, schema evolution, composite objects, and versions. Schema evolution is the ability to dynamically make changes to the class definitions and the structure of the class lattice. Composite objects are recursive collections of exclusive components that are treated as units of storage, retrieval, and integrity enforcement. Versions are variations of the same object that are related by the history of their derivation. These additional features are strongly motivated by data management requirements of object-oriented applications from the AI, CAD/CAM, and OIS (office information systems with multimedia documents) domains. An object-oriented data model, with these enhancements, has been incorporated into ORION, a prototype database system developed at MCC as a vehicle of research into object-oriented databases.