W3C | Architecture Domain | XML

XML Query Working Group Charter

[June 2004]

Paul Cotton, Microsoft, co-Chair,
Andrew Eisenberg, IBM, co-Chair,
Jim Melton, Oracle, co-Chair,
Massimo Marchiori and Liam Quin, Team Contacts

This Working Group follows the rules and requirements of the latest operative version of the World Wide Web Consortium Process Document. Except as outlined elsewhere in this charter, the Working Group follows the Common Procedures for XML Working Groups. The previous charter for this Working Group is also available.

Note: this document was edited on 27 August 2004 to add "XML Path Language (XPath) 2.0" in the set of deliverables, and on 11th october 2006 to update the group's duration through 31st January 2007.

  1. Scope
  2. Deliverables and duration
  3. Expected milestones
  4. Coordination with other Working Groups
  5. Working Group participation
  6. Meetings
  7. Communication
  8. Confidentiality
  9. Patent Policy

1. Scope

The mission of the XML Query working group is to provide flexible query facilities to extract data from real and virtual documents on the Web. Real documents are documents authored in XML. Virtual documents are the contents of databases or other persistent storage that are viewed as XML via a mapping mechanism.

The functionality of the XML Query language encompasses selecting whole documents or components of documents based on specified selection criteria, as well as constructing XML documents from selected components.

The goal of the XML Query Working Group is to produce a formal data model for XML documents with namespaces (based on the XML Information Set), a set of query operators on that data model (a so-called algebra), and then a query language with a concrete canonical syntax based on the proposed operators. The queries allowed by the query language must be computable and terminating. Such queries will act on fixed collections of XML documents.

In building such an XML data model, operators, and query language, the working group will take into account the papers and proposals presented at the W3C Query Languages Workshop (QL'98).

The XML Query Working Group is part of the W3C XML Activity.

2. Deliverables and duration


The XML Query Working Group has prepared distinct working drafts for a) XQuery 1.0, b) XPath 2.0, c) XQuery and XPath Data Model, d) XQuery and XPath Formal Semantics, e) XQueryX, f) XQuery and XPath Functions and Operators, and g) XSLT and XQuery Serialization. It is now clear that these seven Working Drafts should form seven distinct Recommendations. The Working Group will produce the following documents:

After making significant progress on XML Query 1.0, the XML Query Working Group is supposed to develop XQuery 1.1 with additional features not delivered during the XQuery 1.0 period, which might include: a) an update language, b) a grouping facility, etc. This work might involve publishing a subsequent version of XQuery.


The expiration date of this charter is 30 June 2006.

3. Expected milestones

These are subject to revision due to editorial needs and external scheduling issues; updates will be negotiated with the related groups and recorded on the XML Query Working Group home page.

August 2004
November 2004
January 2005
March 2005
June 2005
August 2005
November 2005
December 2005
January 2006
March 2006
June 2006

4. Coordinations with Other Groups

W3C Groups

XML has become a strategic technology in W3C and in the global Web market. The deliverables of the XML Query Working Group must satisfy the dependencies from the following Working Groups before they can advance to Proposed Recommendation.

Some dependencies to and from the following W3C Working Groups will require close cooperation during the development process; the requirements posed for the Query work by these Working Groups may change during the development process, which means the interdependency of the Query work with these Working Groups must be managed actively:

The XPath 1.0 language was jointly developed by the XSL Working Group and the (now defunct) XML Linking Working Group. The XML Query Working Group will collaborate with the XSL Working Group to extend XPath 1.0 to an XPath 2.0 that covers the functionality that is common to both XML Query and XSL.
XML Schema
It is a goal of the XML Query work to be compatible with the work of the XML Schema Working Group on XML Schema Part 2: Datatypes (XML Schema Part 2) and XML Schema Part 1: Structures (XML Schema Part 1). For example, it should be possible to base query predicates on the existing DTD or XML Schema Part 1 definition of the content of an XML document and on the data types defined as part of W3C XML Schema Part 2.
XML Core
The XML Query work will define a formal data model of XML documents. This model must be based on the model of the XML Infoset (XML Information Set). In case incompatibilities arise, requirements must be posed to the XML Core Working Group. In any case, the final model used by the XML Query working group will have to be based on, and totally compatible with, the model of the XML Infoset. In addition any XML Query definition of an XML fragment will take into consideration the XML Fragment Interchange specification (XML Fragment Interchange)
Device Independence Working Group (DIWG)
The DI Working Group develops a Content Selection for Device Independence that is based on XPath. Proper review of the Content Selection document will be necessary.
DOM Interest Group
The XML Query work must take into account the iterators and filters component of the DOM, and wherever possible try to encompass those functionalities into the query language. Alignment of the DOM and XQuery data models will also continue to be investigated with the DOM Interest Group.
Internationalization Working Group
It is a goal of the XML Query work to ensure proper internationalization of the XML Query technology. The mission and scope of the Internationalization Working Group is to propose and coordinate any techniques, conventions, guidelines and activities within the W3C that help to make and keep the Web international. The XML Query Working Group and the Internationalization Working Group will work together to agree on specific I18N requirements and find solutions.

There are no requirements for co-development of features with the following Working Groups, but there are points of contact between their work and that of this Working Group, and thus logical dependency between their deliverables and those of this Working Group. Requirements from these Working Groups are expected to be well suited for communication via documents:

WAI Protocols & Formats Working Group
Reuse of common constructs greatly facilitates accessibility; the WAI PF Working Group will review work on the XML query facilities to be sure cost/benefit design decisions are informed of the benefits of accessibility.
RDF Data Access Working Group
The relationship with XQuery section mentions that the RDF DAWG should aim to maximize W3C technology re-use, such as using the XQuery 1.0 and XPath 2.0 Functions and Operators specification. The RDF Data Access Working Group and the XML Query Working Group will coordinate to ensure the reusability of the XQuery/XPath technologies.

Formal liaison between the XML Query Working Group and other W3C working groups, including the other XML working groups and the WAI (Web Accessibility Initiative) group, as well as organizations outside of the W3C, shall normally be accomplished by the exchange of documents (requirements, reviews, etc.) transmitted through the XML Coordination Group.

When approved by the XML Coordination Group, liaison with other W3C Working Groups can be accomplished through joint task forces. It is expected that this be required for liaison with at least the XML Schema, XSL and Internationalization Working Groups.

5. Working Group participation

The rules for the participation and decision process in the XML Query Working Group are regulated by the Common Procedures for XML Working Groups.

Participation in the XML Query Working Group is expected to consume at least half-day per week of each Working Group member's time, though the time commitment for the Chair and editors may require up to two full days per week.

To be successful, we expect the XML Query Working Group to have approximately 15 to 20 active principal participants for its duration.


The initial Chairs of this Working Group are Paul Cotton, (Microsoft), Andrew Eisenberg (IBM), and Jim Melton (Oracle).

W3C Team resources

The initial W3C Team contacts are Massimo Marchiori and Liam Quin. It is expected that this Working Group would consume about 0.85 FTE, including administrative logistics.

6. Meetings

The Working Group will have distributed and face-to-face meetings.

It is expected that face-to-face meetings will be held about every two to three months.

7. Communication

The XML Query Working Group shall communicate among its participants using the Working Group mailing list w3c-xml-query-wg@w3.org (archive) and with the participants of other XML Working Groups through the w3c-xml-plenary@w3.org mailing list. Both lists are visible to all W3C Members. Other Member-only lists may also be used for internal convenience.

Communications resources for press and media relations and speaking appearances or meeting planning resources are amortized across the working groups in the XML Activity, and concentrated in the XML Coordination Group.

8. Confidentiality

The proceedings of this Working Group are Member-confidential, subject to exceptions made by the Chair with the Working Group's agreement.

In support of public accountability, the Working Group will periodically make public a summary of all technical decisions made since the last public summary, and the rationales for these decisions.

9. Patent Policy

This Working Group operates under the W3C Patent Policy (5 February 2004 Version). To promote the widest adoption of Web standards, W3C seeks to issue Recommendations that can be implemented, according to this policy, on a Royalty-Free basis.

Massimo Marchiori, Liam Quin, Team Contacts

This revision: $Revision: 1.37 $ $Date: 2006/10/12 15:37:47 $ by $Author: liam $