Path: utzoo!mnetor!uunet!husc6!bloom-beacon!mit-eddie!ll-xn!ames!sgi!wdl1!mitchell
From: mitchell@wdl1.UUCP (Jo Mitchell)
Newsgroups: comp.databases
Subject: Object Oriented DBs - worth it?
Message-ID: <3560014@wdl1.UUCP>
Date: 5 May 88 17:32:20 GMT
Lines: 39

This is intended to raise talk on the subject of object oriented database
systems:  are they worth using now or should we all wait 5 years until
they catch up to the goodies offered in RDBS?  Please respond to this
question and any other info you wish to give here.

Rough History:
In January a user requested information concerning object-oriented
databases: what was available, etc.  The MAJOR players were:
	IRIS (HP based, uses OSQL, C & Lisp, has multiple inheritance)
	GBASE (single user, Prolog/LISP)
	GEMSTONE (IBM-PC & Tektronic, C & Smalltalk)
	VBASE (Sun 3 & VMS, OSQL, uses C)
Object oriented databases represent a higher level of abstraction in the
database model (similar to how Fortran was a higher level of abstraction than
Assembly).  Designing applications which use such systems can be thought of as 
designing applications like the Ada method of Booch. 
Increased speed savings is argued - especially for ADVANCED DATA-INTENSIVE 
APPLICATIONS (such as CASE, CAD, CAM, Knowledge Engineering, etc).  
Basic terminology surrounding object oriented systems:
	objects (refers to any conceptual entity: airplanes or a certain
		 airplane, meta data or data.  Consists of some private
		 memory that can be found via a unique identifier)
	class (refers to a group of objects: eg, airplanes).
	property (refers to a prescribed set of characteristics for 
		 a class: eg, size, weight. ASA instance variables)
	instance (refers to a certain class: eg, 747)
	message (refers to the behavior of a class: eg: get_size)
	method (refers to the procedure for implementing the message)
	generalization (refers to class to class mapping: eg: airplane IS-A
			machine)
	composition (refers to class to class mapping. Eg: wing IS_PART of
			airplane)
	inheritance (refers to class to class hand-downs of properties,
			messages and methods. Eg: because you declared size
			and get_size as properties, messages and methods for
			the class airplane, all sub-component classes of
			airplane - such as wing - should inherit these.)
<There is quite alot of reference material. For starters see BYTE 
vol. 11 no 8, Aug 1986 and  ACM TOIS Jan 1987. >