W3C XML Query Language Working Group

Mark NeedlemanData Research AssociatesZIG Current Awareness SessionJuly 13, 2000

Other DRA Interest

XML in General HTML CSS Accessibility Initiative Metadata - RDF Privacy Electronic Commerce URI’s

QL Working Group Charter

Formal Data Model based on XML Infoset

Formal Algebra One or More Concrete Canonical

Syntaxes based on Data Model and Algebra - One Syntax must be expressed in XML - One Syntax must be “Human Friendly”

QL Workshop 98

W3C sponsored event - Boston Dec 2-3

98 participants - 66 position papers W3C members, database vendors,

invited experts See:

– http://www.w3.org/Tands/QL/QL98

W3C QL WG History and Status Proposed July 1999 as part of XML

Phase 3 Activity September 99 - Call for Participants

and group chartered 1st Face to Face meeting - Sept 15-16 2nd Face to Face December 2-3 3rd Face to Face February 7-8, 2000

Status (2)

4th F2F April 11-12 2000 5th F2F June 5-6, 2000 3 more F2F meetings scheduled for 2000 Requirements Document Published Jan 2000 as

W3C Note - has been revised based on comments received

1st Public Working Draft on Data Model Published May 2000

Currently working on Formal Algebra - Targeted for September 2000

QL Status (3) Currently about 60 members plus 5 Observers

members - largest W3C Working Group Weekly teleconference calls Public working drafts every 3 months One or more proposed recommendations is the

goal Have also developed a set of Usage Scenarios to

validate data model and algebra - To be Published July 2000 with Revised Requirements Document

QL Requirements

Possible multiple syntaxes - at least one expressed using XML - one must be human friendly

Defined independently of any protocol with which it is used

must not preclude possibility of Updates must support real and “virtual “ XML

documents must support collections of documents

Requirements (2)

Must support XML namespaces must support datatypes from XML Schema able to combine related elements from a

single or multiple documents Extensibility mechanism provide access to document DTD or schema

if available operations on text must be applicable to text

that spans element boundaries

Requirements (3)

Support Internationalization traverse inter and intra document references preserve hierarchy and sequence of document

structure in query results have ability to transform XML structures and create

new ones Must not enforce any particular evaluation strategy must be able to provide access to information

derived from the environment in which the query was executed (I.e current time, date or user information)

Potential Usage Scenarios Defined in Requirements Doc XML Document search and

management XML processing of DBMS data Integration of Multiple XML Sources Filtering Streams of XML data

Usage Cases Developed by WG

Each focuses on a specific application area

Each one contains sample DTD and data Each one contains sample queries Goal is to use them to validate data

model, algebra and syntax’s Living document - new uses cases can

be submitted

Usage Cases

Access to Relational Databases Text Retrieval Use of XML Namespaces Use Cases based on some Sample Query

Protocols Developed in Research Community Use of References and IDREF Preservation of Hierarchy and Sequence Queries Based on Document Structure and

Tagging

Current Mention of Z39.50

Usage Scenario Section- Following Text:– Queries may be used in many environments.

For example a query might be embedded in a URL, an XML page, or a JSP or ASP page; represented by a string in a program written in a general purpose programming language; provided as an argument on the command-line or standard input; or supported by a protocol such as DASL or Z39.50

Liaison Section Several Other W3C Working Groups

– DOM, XNL Schema, XSL, XPointer, XML Fragment, Internationalization Working Group, XML Fragment

IETF DASL - Language Reads:– XML Query must strive for smooth interaction

with the IETF DASL (DAV Searching and Locating) Working Group, in such a way that the XML Query Language can be easily incorporated into the DASL Protocol

QL Liaison with Z39.50 Proposed language similar to that for DASL Decision made not to do this - DASL

language was their because they had deferred their query language to QL WG - For Z39.50 (and other communities like SQL) it was felt the way to go was to make sure those communities were kept informed and their input was solicited -Chair agreed to work me on this for the ZIG

Relationship to Z39.50

Conservative: Possible new Query Type in Existing Z39.50 protocol

Radical: Basis for a total restructuring of Z39.50 functionality with XML Query Language as the core - what this would look like would need to be defined

Publicly Available Documents

Requirements Document http://www.w3.org/TR/xmlquery-req

Public Draft of Data Model– http://www.w3.org/TR/query-datamodel/