# Presentation: 233014

## W3C XML Query Language WG

**Mark Needleman**
**DRA**
**ZIG Tutorial**
**January 19, 2000**

## 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 scheduled for early February**

## QL Status (2)

**Currently about 55 members - largest W3C Working Group**
**Weekly teleconference calls**
**Requirements document being finalized - will be submitted as a W3C Note**
**Public working drafts every 3 months**
**One or more proposed recommendations is the goal**

## Potential 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

**XML Document search and management**
**XML processing of DBMS data**
**Integration of Multiple XML Sources**
**Filtering Streams of XML data**

## 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**