Re: Table vs. XML Thoughts

[Subbarao Kambhampati <rao@asu.edu>]

Ease of data exchange is the main and about the only advantage if all
you are trying to do is represent relational data--RDBMS clearly
provides a tighter storage. 

XML does offer representational support for semi-structured
data--i.e., data which does not conform to a single schema but rather
to a union of schemas. E.g. a person may have zero, one or two phone
numbers. 

We will see more about it in today's class

Rao
[Apr  4, 2001]


From: "David J. Borough" <david.borough@asu.edu>
Subject: Table vs. XML Thoughts
Date: Wed, 04 Apr 2001 08:11:29 -0700
Message-ID: <004001c0bd19$8a80c1e0$3c91e43f@davidjess>

david.borough> Dear Subbarao,
david.borough> 
david.borough> Thinking about the 2 storage representations of a simple relation given in
david.borough> class, I find that they each store the same information.  The table is
david.borough> presented visually, as is the XML text.  However, both can be stored in data
david.borough> structures.  The XML is more redundant by repeating the headings.  The only
david.borough> advantage I find with the XML comes from the redundancy.  It allows the
david.borough> headings to change for each tuple.  It allows tables within table cells,
david.borough> basically. Because of that ability, XML can be used to translate from one
david.borough> database to another without knowing the structure of the other database.
david.borough> Database Administrator A, let's call him, can translate Database A to XML.
david.borough> Database Administrator B, can then translate the XML to Database B.  That is
david.borough> the advantage I see with XML.  Perhaps the semi-structured-ness lends itself
david.borough> well to these types of translations.  Maybe information is lost, I don't
david.borough> know.  What do you think?  I don't see much more advantage to the XML, other
david.borough> than it provides the flexibility of virtual tables within table cells.
david.borough> 
david.borough> Sincerely,
david.borough> 
david.borough> David J. Borough
david.borough> dj@davidjess.com
david.borough> www.davidjess.com
david.borough> 
david.borough> ----- Original Message -----
david.borough> From: "Subbarao Kambhampati" <rao@asu.edu>
david.borough> To: <cse494-s01@asu.edu>
david.borough> Sent: Tuesday, April 03, 2001 6:59 AM
david.borough> Subject: answer to Eric's question on DTD extensions [Fwd: DTD structure]
david.borough> 
david.borough> 
david.borough> > While general inheritance is not supported, one level internal overrides
david.borough> to
david.borough> > an external DTD are supported...
david.borough> >
david.borough> >
david.borough> > >Date: Mon, 02 Apr 2001 22:50:15 -0700 (MST)
david.borough> > >From: Ullas Nambiar <mallu@asu.edu>
david.borough> > >Subject: DTD structure
david.borough> > >To: rao@asu.edu
david.borough> > >
david.borough> > >
david.borough> > >
david.borough> > >Source: XML companion - Niel Bradley.
david.borough> > >
david.borough> > >"Some DTD declarations maybe stored within the document, called "internal
david.borough> > >subset", remaining stored in a separate data file, are described as
david.borough> > >"external subset" of DTD.
david.borough> > >
david.borough> > >An entity declaration in the internal subset can be used to override the
david.borough> > >value of an entity in the external subset.
david.borough> > >
david.borough> > >example.
david.borough> > >
david.borough> > ><!DOCTYPE MYBOOK SYSTEM "C:\DTDS\MYBOOK.DTD" [
david.borough> > ><!ENTITY % paraModel "#PCDATA | STUB | SUP">
david.borough> > >]>
david.borough> > >
david.borough> > >
david.borough> > >This does make it look like a one level inheritance occuring.
david.borough> > >
david.borough> > >Ullas
david.borough> > >
david.borough> > >
david.borough> > >"Well Begun is Half Done"
david.borough> >
david.borough> >
david.borough>