THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
Metadata
Danielle Cunniff Plumer
INF 385T: Knowledge Management Systems
Prof. Don Turnbull
February 11, 2003
Revised
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
What is Metadata?
• “[structured] data about data”
• Irrelevant factoid: A company called
Metadata®, in attempting to protect
its trademark, has threatened legal
action against business for using the
term generically. See
http://www.metadata.com/
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
Metadata definition
•
Meta data, n. [from L. meta-; Gr. meta- and L. data]
Data that characterizes other data in a reflexive way,
e.g., data about data. Analogous to words about words.
In data processing, it is definitional data that provides
information about or documentation of other data
managed within an application or environment. For
example, meta data would document data about DATA
ELEMENTS or ATTRIBUTES, (name, size, data type, etc)
and data about RECORDS or DATA STRUCTURES (length,
fields/columns, etc) and data about DATA (where it is
located, how it is associated, ownership, etc.). Meta data
may include descriptive information about the context,
quality and condition, or characteristics of the data.
– Retrieved February 11, 2003, from
http://www.metadata.com/word.htm
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
Dublin Core
• “The Dublin Core Metadata Initiative
(DCMI) is an organization dedicated to
fostering the widespread adoption of
interoperable metadata standards and
promoting the development of
specialized metadata vocabularies for
describing resources to enable more
intelligent resource discovery
systems.”
– Retrieved February 11, 2003, from
http://www.dublincore.org/resources/faq/
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
DCMI Elements
• Originally 15 elements
• Currently, the full set
includes 46 elements
– http://dublincore.org/usage/
terms/dc/current-elements/
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
Basic DCMI Elements
•
•
•
•
•
•
•
•
title
creator
subject
description
publisher
contributor
date
type
•
•
•
•
•
•
•
format
identifier
source
language
relation
coverage
rights
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
Questions to ponder
• HMTL <meta> tags are currently not
used by search engines. Will this
change? How/why?
• Dornfest and Brickley talk about
“implicit metadata” on p. 193. What
are the implications of this?
• Problems of ambiguous metadata (p.
194): how does XML resolve this
(namespaces)?
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
Dublin Core Generators
• Nordic DC metadata creator
(including URN generator)
http://www.lub.lu.se/cgibin/nmdc.pl
• For more Dublin Core tools, see
http://dublincore.org/tools/
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
XML
• eXtensible Markup Language
• XML is a metalanguage; that is,
it allows the creation of domainspecific markup languages based
on a structured syntax
• XML says nothing about meaning
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
RDF
• Resource Definition Framework
• “The Resource Description Framework
(RDF) is a language for representing
information about resources in the
World Wide Web. It is particularly
intended for representing metadata
about Web resources”
– Retrieved February 11, 2003, from
http://www.w3.org/TR/rdf-primer/
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
RDF Illustrated
A simple RDF statement.
Source: Manola, Frank, & Miller, Eric. (2003). RDF Primer.
Retrieved February 11, 2003, from
http://www.w3.org/TR/rdf-primer/
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
Sample RDF Metadata
<rdf:RDF
xmlns:contact="http://www.w3.org/2000/10/swap/pim/contact#"
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:doc="http://www.w3.org/2000/10/swap/pim/doc#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns="http://www.w3.org/2001/02pd/rec54#">
<WD rdf:about="http://www.w3.org/TR/2003/WD-rdf-primer-20030123/">
<rdf:type rdf:resource="http://www.w3.org/2001/02pd/rec54#LastCall"/>
<dc:date>2003-01-23</dc:date>
<dc:title>RDF Primer</dc:title>
<lastCallFeedBackDue>2003-02-21</lastCallFeedBackDue>
<cites><ActivityStatement rdf:about="http://www.w3.org/2001/sw/Activity"/></cites>
<doc:versionOf rdf:resource="http://www.w3.org/TR/rdf-primer/"/>
<doc:obsoletes rdf:resource="http://www.w3.org/TR/2002/WD-rdf-primer-20021111/"/>
<editor rdf:parseType="Resource">
<contact:fullName>Frank Manola</contact:fullName>
<contact:mailbox rdf:resource="mailto:fmanola@mitre.org"/></editor>
<editor rdf:parseType="Resource">
<contact:fullName>Eric Miller</contact:fullName>
<contact:mailbox rdf:resource="mailto:em@w3.org"/></editor>
</WD>
</rdf:RDF>
RDF Primer Metadata. Retrieved February 21, 2003, from http://www.w3.org/TR/rdf-primer/metadata.rdf
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
Questions to ponder
• Dornfest and Brickley claim that
“Unique identifiers create
markets” (p. 201). Their
examples:
– Collaborative filtering
– E-commerce
– Discovery
• Are they right? Or is this more
visionary hyperbole?
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
The Semantic Web
• Elements:
– XML
– RDF
– Ontologies
– Agents
– Digital signatures
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
Ontology
• “an ontology is a document or
file that formally defines the
relations among terms. The most
typical kind of ontology for the
Web has a taxonomy and a set
of inference rules”
– Source: Berners-Lee, T., Hendler, J. and Lassila, O.
(2001). The Semantic Web. Scientific American.
Retrieved February 11, 2003, from
http://www.scientificamerican.com/print_version.cfm
?articleID=00048144-10D2-1C7084A9809EC588EF21
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
Semantics
•
•
•
SYLLABICATION:se·man·tics
PRONUNCIATION: s -m n t ks
NOUN:(used with a sing. or pl. verb)
1.
2.
3.
–
Linguistics The study or science of meaning
in language.
Linguistics The study of relationships
between signs and symbols and what they
represent. Also called semasiology.
The meaning or the interpretation of a word,
sentence, or other language form: We're
basically agreed; let's not quibble over
semantics.
The American Heritage Dictionary. (4th ed., 2000).
Retrieved February 11, 2003, from
http://www.bartleby.com/61/83/S0248300.html
THE UNIVERSITY OF TEXAS AT AUSTIN
School of Information
Questions to Ponder
• What does “Semantic” mean in
the context of the “Semantic
Web?”
• Should there be one central
ontology or multiple ontologies?
• What are the privacy and
security implications of agents?