W3C XML Query Language Working Group

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W3C XML Query Language Working Group

• Mark Needleman
• Data Research Associates
• ZIG Current Awareness Session
• July 13, 2000

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Other DRA Interest

• XML in General
• HTML
• CSS
• Accessibility Initiative
• Metadata - RDF
• Privacy
• Electronic Commerce
• URIs

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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

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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

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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

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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

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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

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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

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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

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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)

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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

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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 syntaxs
• Living document - new uses cases can be submitted

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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

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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

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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

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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

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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

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Publicly Available Documents

• Requirements Document http//www.w3.org/TR/xmlquer
  y-req
• Public Draft of Data Model
• http//www.w3.org/TR/query-datamodel/