TECFA's XQuery Page

(only sporadically updated)
Keywords: XML
Related Pages: XML Applications Pointers (DTDs, Schemas), XSL Pointers, DOM Pointers, SVG Pointers, RDF pointers, Cocoon Pointers.

Xquery is a query language that uses the structure of XML intelligently can express queries across all these kinds of data, whether physically stored in XML or viewed as XML via middleware. In other words, you can use it to retrieve things from files, from XML representations made from SQL databases, from native XML databases like exists. In addition, Xquery is quite a real programming language. XUpdate is a protocol to updated (XQuery can't). XML Databases are servers in which can plug XML "as is" and get it back with Xquery and/or XSLT.

XQuery and XML Databases @ TECFA

We don't use it (yet). I just played arount with the eXisT dabase and the Xquery processor of saxon. I have the impression that XQuery also can replace parts of what is done now with XSLT (much easier to write "real" programs").

Documentation & Validation

On-line Validation

W3C HTML Validation Service This validator doesn't always work with your own DTD's. Its primary function is to validate W3C vocabularies (HTML, XHTML, SVG, MathML, ... )

Manuals

Specifications

XQuery 1.0: An XML Query Language (the central document). XQuery can only query (not update).
There are some other parts, e.g. XML Query Use Cases and XML Query Requirements and XML Query Data Model (W3C Working Draft). XQuery is a full programming language and comes with 2 syntaxes: one humain readable and on in XML ;)
xqupdate - XQuery Update Facility. This will replace Xupdate (a very informal "standard") [W3C Working Draft 27 January 2006]
Xpath 2.0 is used both by XSLT 2.0 and XQuery. XQuery is an extension of XPath 2.0 and both XSLT 2.0 and XQuery 2.0 share the same data model.
Xupdate can be used to update some XML databases (not updated since 2000 ?). Xupdate looks a lot like XSLT.

Short manuals

XML:DB XUpdate Use Cases by Kimbro Staken. This document outlines a basic set of uses cases for the XUpdate specification from the XML:DB Initiative.

XML database manuals

Xindice Documentation @(includes XML:DB and XUpdate information useful for other servers)
Xindice documentation @ Apache. Of particular interest: Developer guide
eXist documentation @ sourceforge.

XQuery Tutorials

Essential XQuery - The XML Query Language by Darshan Singh. (Feb 2, 2004)
Xquery: A guided Tour (PDF) by Jonathan Robie. Good introduction. (some Syntax may have changed !!) [7 / 2003]
An introduction to XQuery article for recent developments (2002, updated 2003).
XQuery, tutorial by Anders Møller & Michael I. Schwartzbach [2003]
XQuery Tutorial from IPEDO. Quite technical.
XQuery from the Experts: Influences on the design of XQuery Webreference Article, excerpt is from Chapter 2 of the Addison-Wesley book XQuery from the Experts. [2003]
Michael Brundage (2004). XQuery: The XML Query Language, Portland: Book News [this is a good book]

XML Database Tutorials

XML and Databases good overview by Ronald Bourret
Managing XML data (So far) four IBM Developperworks articles by Elliotte Harold (2005). Good introduction, e.g. see Managing XML data: Native XML databases.

Software

XML databases

Xindice is a native XML database. Supports XPath queries and XML:DBXUpdate. Java and has a XML-RPC API plugin. It has grown out from dbXML is a native XML database (JDK 1.3, LGPL licence). See also the Xindice Wiki at Apache for more information, e.g. a pointer to XIndicePHPAdmin. There exist other PHP libraries, but most projects seem to be inactive. [This project seems to stall since sept 2004, see dbXML or eXist)
dbXML, GPL license. dbXML is a Native XML Database (NXD). NXDs are databases that store XML using an internalized format for faster overall processing. dbXML was developed using the Java 2 Standard Edition version 1.4.
eXist XML database and retrieval engine, an alternatives to popular Xindice. [1.0b2 in 6/2005, tested @Tecfa but in in production - faster (for lots of small documents) than Xindice, more other features too that I like: XQuery, XUpdate, XML:DB API, xml-rpc support, REST support, WebDav, PHP API (needs dowloading from CVS), good Cocoon Integration ]. A side note for qualitative analysis people: seed XML DBs as Research Tools (by darcusblog)
DB2XML: A tool for transforming relational databases into XML documents As Servlet or standalone. Xindice is a fork of this (don't know if db2xml development continues).
Oracle Berkeley DB XML. Oracle Berkeley DB XML is an open source, embeddable XML database with XQuery-based access to documents stored in containers and indexed based on their content. Oracle Berkeley DB XML is built on top of Oracle Berkeley DB and inherits its rich features and attributes. [Not tested / DKS 12/2006]

Engines

SAXON XSLT and XQuery Processor INSTALLED and used as default XSLT engine at Tecfa: local documentation.
XQEngine - XML Query Engine implements XQuery - sourceforge project.
MXQuery. low-footprint, extensible XQuery Engine (Java). Includes support for update

XQuery clients & libraries

Safari Guide Safari Guide is a free application for Mac OS X Tiger that allows developers to evaluate arbitrary XPath and XQuery expressions against the current frontmost Safari webpage. [10/2005]
XMLdbGUI is an XML:DB API compliant implementation that should work with eXist and Xindice(not tested).