# Presentation: 144559

## W3C XML Query Language 				Working Group

**Mark Needleman**
**Data Research Associates**
**ZIG Current Awareness Session**
**July 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/](http://www.w3.org/TR/xmlquery-req)__[xmlquery](http://www.w3.org/TR/xmlquery-req)__[-](http://www.w3.org/TR/xmlquery-req)__[req](http://www.w3.org/TR/xmlquery-req)_** **
**Public Draft of Data Model**
**http://www.w3.org/TR/query-datamodel/**