XQL: Proposal for a new XML Query Language
November 9, 1998
The Seybold Report on Internet Publishing
Special to XML.com
Representatives from Microsoft, Texcel and WebMethods have submitted to the W3C a position paper that proposes using XSL as the basis for a general-purpose query language for XML documents.
Microsoft is backing the proposal, which would handle documents as well as data, differing from the SQL-oriented XML-QL spec submitted to the W3C by AT&T Labs in August.
Jonathan Robie of Texcel, one of XQL's co-authors, noted several signficant aspects of the proposal:
- "It allows XML documents to be queried like a database;
- It has a model that is directly based on the relationships found in XML documents, which allows powerful queries to be simply expressed;
- It uses a string syntax that allows queries to be used in URLs or embedded in attributes, e.g. for links or XSL Patterns; and
- It is easy to do a naive implementation, but also possible to optimize for large-scale repositories."
Robie also pointed out that the XQL group saw an opportunity to incorporate XSL into the query language the group was designing for XML documents. "XQL originated as a query language; XSL Patterns originated as a means of testing nodes to see if they meet certain criteria. Over time, XQL and XSL Patterns evolved to where they were quite similar, and we found that by adopting a few syntactic changes, we could make XSL Patterns a subset of XQL," Robie said.
A W3C workshop on query languages is slated for Dec. 3 and 4 in Boston. Representatives from a variety of backgrounds are expected to attend, as the agenda includes trying to "clarify the shared and individual needs of different W3C groups like XML, RDF, P3P, and the DOM." The workshop also will give the commercial database vendors a chance to weigh in with their needs.