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Re: [zzdev] RDBMS?

On Sat, Oct 24, 1998 at 07:20:32PM +0900, Kenichi Unnai wrote:
> I recently knew about RDBMS (Relational DataBase Management System).
> Do you know that?
> If you do, do you find any difference between zigzag and RDBMS?
> I know zigzag is not database, it's environment, but I think it's the same
> thing with the concept of hypertext.
> Hypertext is also the environment, but in another point of view,
> it's world-wide distributed database system.
> I need to explain to some guys how different zigzag and RDBMS.
> I'm striving to do, but I can't have a clear idea.
> Or can it be compatible with each other?
> What I want to do is to get a clear explanation that how different, and
> what the good/bad point are there.
> Any idea?

Well, the concept of "database" is very broad (it just means a collection
of data which users can access and modify) and both Zigzag and hypertext
build on top of collection of data.  However, a relational database
(RDBMS) is a specific kind of database where the data is structured into
"relations", defined as tables containing rows ("records") and columns

Hypertext (or hypermedia) provides for connections between data in the
form of "links" and/or "transclusions", which can be layered on top of
just about any kind of database system including RDBMSes.  However the
hypertext/hypermedia concept does not prescribe any particular structure,
instead enabling each user to create their own structural arrangements
of the underlying information.

Zigzag is in a sense a specific example of hypermedia because it also
provides for connections between data elements including both links
and transclusions ("clones"), but it does enforce a few structural
rules - all links must be typed (in a named dimension), bidirectional
and one-to-one, and data elements are not required to partcipate in
any particular dimensions.  These rules could also be implemented as
an additional layer over an existing RDBMS - indeed this is one of the
topics currently under discussion on the Zigzag developer mailing list.
However a conventional RDBMS by itself does not provide the more powerful
structuring and viewing facilities of Zigzag.

Hope that helps,
		*** Xanni ***
mailto:xanni@xxxxxxxxxx                         Andrew Pam
http://www.xanadu.com.au/                       Technical VP, Xanadu
http://www.glasswings.com.au/                   Technical Editor, Glass Wings
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P.O. Box 26, East Melbourne VIC 8002 Australia  Phone +61 3 96511511