Enterprises are looking for consistent, native XML support across competing databases as a solution to integration problems, but IBM, Microsoft, and Oracle have yet to agree on a consistent approach.
XML itself may also be an obstacle, as its wordiness can choke application performance.
IBM is poised to announce support for the XML query language XQuery next month, when it delivers the next beta version of its DB2 database to select customers.
The final product, Xperanto, will exploit XQuery more fully and will build on IBM's goal of seamlessly marrying structured and unstructured data across diverse environments. Xperanto is due to ship later this year.
Meanwhile, Oracle is exploiting existing investments in object databases to flesh out XML support in its XDB architecture and has plans to incorporate XQuery.
Microsoft is also planning XQuery support. It is working to marry its structured and unstructured databases with SQL and Exchange Server, respectively, wrapping XML in a relational format with SQL XML.
At the same time, native XML database players such as Ipedo, Software and NeoCore are gathering steam, seeking direct expression of XML content in the database itself.
"[Customers] need to combine XML technology with the ability to move across existing infrastructures and existing data stores. That is basically our strategy," said Nelson Mattos, distinguished engineer and director of information integration at IBM's Silicon Valley labs.
"Customers tell us they cannot use a rip-and-replace strategy, which says, 'I cannot accept the strategy that says to move everything into my database.' That is unreal. [Customers] would be spending money to replace infrastructure already up and running and returning results," Mattos said.
Carl Olofson, program director for information and data management software research at analyst group IDC, disagreed. He said enterprises wanted a single database for both XML documents and other structured data.
"The reason XML data will be important is, if you want to store enterprise-relevant information - business-critical or mission-critical - you probably want to do that in one database," Olofson said.
Oracle's architectures, including Oracle Call Interface and Oracle XML DB, are designed to enable XML to access structured data and content and include emerging support for SQL XML and X Path, as well as a prototype implementation of XQuery available for download.
"The point is, users should be able to access XML data natively," said George Demarest, senior director of database marketing at Oracle. "Our goal was to make XML data basically appear within the Oracle server as standard relational tables."
Rather than pursue its previous approach of employing multiple database engines, Microsoft is building a 64-bit XML database - codenamed Yukon and due for release next year - around SQL XML.
"We built some additions to the SQL language capability to return that data as XML. SQL XML is part of it; the rest of it is focused on the ability to expose stored procedures, which are SQL code, as Web services," said Eric Brown, product manager for SQL Server at Microsoft.
Microsoft released its latest version of SQL XML, Version 3.0, in February and will support XQuery in late 2003, company officials said.