Architects
XQuery for the systems analyst or architect
The W3C XML Query Working Group worked with the W3C XML Schema WorkingGroup and the W3C XSL Working Group to make a set of specifications thatall work together.
Use XQuery to take data from multiple databases, fromXML files, from remote Web documents, even from CGI scripts,and to produce XML results that you can process with XSLT.
Use XQuery on the back-end of a Web server, or to generateEnterprise-wide executive reports.
Examples of XML Query In Action
Submit your entry by sending mail to liam at w3.org,with [XQuery site] in the subject. Remember to give the fullURL, and remember that it must be public.
Oxford African American Studies Center is a site publishedby Oxford University Press using an XQuery system. See theSite Credits link there for more details.
Alberta learning Centerfor education in the Canadian province of Alberta; e.g. seethe Search link, which does not require registration.
AuthorMappershows authors of scientific papers and articles broken downby geography and subject. The site is by Springer.
Business Week Business School Comparatoris said to use XQuery to let users compare universities andbusiness schools; it didn't seem to work for me, so maybe IE only?Or maybe I'm not cut out for business.
Business Exchange, another Business Week site, uses XQuery to drive a site where, itsays, usiness professionals can collaborate and networkaround business topics.
CQ Legislative Impact isa tool to explore how pending US legislation might affectexisting laws.
Data Request Broker,DRB, at Gael Consultant, is an open source Java API for processingheterogeneous data. It includes XQuery and Scema support. License is LGPL.
TheDolley Madison Digital Edition by the University of Virginia Press.
fromoldbooks.org has an image search engine powered by XML Query; you can see the text of the queries (follow the About link on the Search page). This is also used by Liam Quin's Photograph search page.
MarkMail is an XQuery-basedapplication for searching and visualising mailing lists.
The New England Journal of Medicineuses XQuery to search and retrieve comprehensive case summaries andgraphical icons that identify available supplemental content such aslab reports, radiological scans, histopathology slides, and photosassociated with a particular case record.
O'Reilly Labs useXQuery to power code search, image search,statistics and more.
Pop Culture Universeis a Web site about American popular culture, including movies,books and music, with over 300publications indexed and searchable.
Springer Images uses XQueryto search and retrieve scientific images, photos, tables, charts etc. for researchers.
Springer Exemplarprovides a full-text interface to large numbers of scientificand technical journals, together with tools for narrowing downsearch results.
Wiley Custom Select is a Web site for creating custom course books.
Worldcolorhas a custom publishing system using XQuery; they havea Flash demo.
Have you got a Web site that's powered by XML Query?A success story to share? Contact liam at w3.org.
Users
XQuery: choosing an implementation
There are over 40 different software packages thatsupport XML Query in some way. Things to look forinclude availability of support, platforms, price,performance, all the usual issues, but you should alsoask whether the software supports the final syntax fromthe W3C Recommendation or implements an earlier draft.Another XML Query specific feature is support forXML files, for fetching documents via HTTP, and forconnecting to relational (or other) data sources: that is,whether the package lives up to the XML Query promise ofunifying access to many different forms of information.
List of XQuery Implementations
Learning
There are some books listed; there are also peopleoffering training and tutorials. If there is anythingyou found particular helpful, let us know!
There are also some mailing lists devoted to XMLand to XML Query. You should look at the archives of each listbefore posting; you'll also need to subscribe to the list beforeyou can post to it in most cases.
- www-ql
This is the W3C public mailing list on query languages, including (but not limited to) discussion on the XML Query project. Do not use this to send comments on the specification, such as errata or feature requests; see the Status section in each specification for instructions on how to send comments to the Working Group.
- xquery-talk
A mailing list hosted at x-query.com, especially for discussing XQuery.
- xml-dev
Probably the most widely-known list for discussing XML.
Reading the Specs
W3C Specifications are aimed first and foremostat programmers writing implementations of them.We also try to make them readable for people tryingto learn the language—but given a choice betweenmaking a standard precise and making it easy to read,we have to make it precise.
If you are fairly technical, you could start byreading the XML Query specification, and theXQuery Use Cases document has some examples.Many people would rather look for a book or tutorial.
Implementers
XQuery for the implementer: hard core query
Implementers: what would you most like to see here?What would have helped you the most?
The XQuery Test Suite
W3C test suites exist to show that specifications can be implemented. They are testing the specs, not thecode!
The QT 3.0 Test suite is for people implementing XQuery 3, XPath 3, Functions and Operators 3 and related specifications.
XQuery and XPath Full Text 1.0 Test Suite (Joint with the XSLT WG)
The much older XQuery 1.0 Test Suite is no longer used.
Static Typing and Formal Semantics
XPath 2 has typed values; that is, the languageassociates a value type with each expression, variable orfunction. The set of possible types is that defined byW3C XML Schema, augmented by user-defined types derived fromthose basic Schema types using an external schema. The wayin which an XPath or XQuery system derives and checks the type ofan expression is defined formally, using a mathematical notation,in the XQuery 1.0 and XPath 2.0 Formal Semantics Recommendation.
Note that both external W3C Schema support and static typingare optional features, so not all implementations support them.
Conformance Statements
You will often see things in the specifications marked asbeing implementation defined. You must documentwhat your implementation does for each of these.
