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pcplantdb - Re: [pcplantdb] Re: PC DB, XML

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  • From: John Schinnerer <eco_living@yahoo.com>
  • To: pcplantdb@lists.ibiblio.org
  • Subject: Re: [pcplantdb] Re: PC DB, XML
  • Date: Sun, 13 Oct 2002 23:26:51 -0700 (PDT)

Aloha,

Anyone not real clear on XML and DBs ought to read this (LL already
posted this URL), especially section 2.0, which makes it clear why XML
documents per se are a poor choice for a large complex database of any
kind:

http://www.rpbourret.com/xml/XMLAndDatabases.htm

The most salient bits:

"An XML document is a database only in the strictest sense of the term.
That is, it is a collection of data. In many ways, this makes it no
different from any other file -- after all, all files contain data of
some sort. As a "database" format, XML has some advantages. For
example, it is self-describing (the markup describes the structure and
type names of the data, although not the semantics), it is portable
(Unicode), and it can describe data in tree or graph structures. It
also has some disadvantages. For example, it is verbose and access to
the data is slow due to parsing and text conversion.

A more useful question to ask is whether XML and its surrounding
technologies constitute a "database" in the looser sense of the term --
that is, a database management system (DBMS). The answer to this
question is, "Sort of." On the plus side, XML provides many of the
things found in databases: storage (XML documents), schemas (DTDs, XML
schema languages), query languages (XQuery, XPath, XQL, XML-QL, QUILT,
etc.), programming interfaces (SAX, DOM, JDOM), and so on. On the minus
side, it lacks many of the things found in real databases: efficient
storage, indexes, security, transactions and data integrity, multi-user
access, triggers, queries across multiple documents, and so on.

Thus, while it may be possible to use an XML document or documents as a
database in environments with small amounts of data, few users, and
modest performance requirements, this will fail in most production
environments, which have many users, strict data integrity
requirements, and the need for good performance."


I believe Rich already indicated how he was planning to use XML - that
is, he'd use PHP to generate XML based on data from the DB (the DB
itself being MySQL, as I recall, or some open source SQL DB anyhow).

Rich, why XML? As an all-purpose go-between document, or...?


=====
John Schinnerer, MA
-------------------------
- Eco-Living -
Cultural & Ecological Designing
People - Place - Learning - Integration
john@eco-living.net
http://eco-living.net

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