XML Features of Oracle 8i and 9i (1/7) - exploring XML | WebReference

XML Features of Oracle 8i and 9i (1/7) - exploring XML

XML Features of Oracle 8i and 9i

Today, guest writer and database specialist Simon Hume chips in with an introduction to the XML features of the most recent Oracle database versions:

Overview: XML compared with RDBMs

XML and relational databases are both technologies for structuring, cataloguing and processing data. If data has a regular and atomic structure, it is more appropriate and efficient to use a database than XML. In this case, why would you wish to go to the trouble of converting such data from a database into XML and vice versa? Reasons include:

On the other hand text documents, which are usually irregularly structured, cannot be effectively stored in a relational database. In this case, you can only store them in the database as BLOBs, which cannot be searched or processed in the normal way. However, there are cases where this is still desirable: very large repositories of pre-existing XML/SGML documents. The database can be used for cataloguing and searching, and documents once extracted can be processed further using XSL/XSLT.

So there are two possibilities: perform backwards and forwards conversion of data between the database and XML, or store complete XML documents inside the database. Oracle terminology calls the former "generated XML", and the latter "authored XML".

And there are essentially two reasons for using XML and databases together: The first Oracle calls "content and document management" where the requirement is for data to be presented differently as required, the second "B2B messaging" where XML is used to communicate between different applications/sites/companies (cf EDI).

Oracle Tools

The XML tools provided with Oracle are mainly to simplify conversion between the database and XML, and a standard XML parser for the usual XSL/XSL-T/DOM/SAX operations.

The main tools are:

On to real-world examples and code...

Produced by Michael Claßen

URL: http://www.webreference.com/xml/column81/index.html
Created: May 10, 2003
Revised: May 10, 2003