“ Integrating Standards in Practice” 10th Open Forum on Metadata Registries July 9-11, 2007 New York City, NY USA An international conference to share and advance knowledge and experience about standards; the technologies that build upon them, and implementation experiences. SKOS: Simple Knowledge Organization System Jon Phipps Alistair Miles

What is it? S imple K nowledge O rganisation S ystem(s) SKOS is … for declaring and publishing taxonomies , thesauri or classification schemes , for use in a distributed, decentralised information system (I.e. a semantic web). for describing Concepts and creating relationships between Concepts and Terms A practical application of RDF the application of library science to the semantic web. SKOS provides a formal language for representing controlled, structured vocabularies

S imple K nowledge O rganisation S ystem(s)

SKOS is …

for declaring and publishing taxonomies , thesauri or classification schemes , for use in a distributed, decentralised information system (I.e. a semantic web).

for describing Concepts and creating relationships between Concepts and Terms

A practical application of RDF

the application of library science to the semantic web.

SKOS provides a formal language for representing controlled, structured vocabularies

SKOS Since Open Forum 2005 … Quick Guide to Publishing a Thesaurus on the Semantic Web First Working Draft May 2005 http://www.w3.org/TR/swbp-thesaurus-pubguide/ SKOS Core Guide & SKOS Core Vocabulary Specification Second Working Draft published November 2005 http://www.w3.org/TR/swbp-skos-core-guide/ http://www.w3.org/TR/swbp-skos-core-spec/ SKOS Core is now just plain old SKOS W3C Semantic Web Deployment Working Group Kicks Off W3C Recommendation Track http://www.w3.org/2006/07/SWD/ SKOS Use Cases and Requirements First Working Draft Published (2007-05-16) http://www.w3.org/TR/skos-ucr/ New SKOS Web Site http://www.w3.org/2004/02/skos/

Quick Guide to Publishing a Thesaurus on the Semantic Web

First Working Draft May 2005 http://www.w3.org/TR/swbp-thesaurus-pubguide/

SKOS Core Guide & SKOS Core Vocabulary Specification

Second Working Draft published November 2005 http://www.w3.org/TR/swbp-skos-core-guide/ http://www.w3.org/TR/swbp-skos-core-spec/

SKOS Core is now just plain old SKOS

W3C Semantic Web Deployment Working Group Kicks Off

W3C Recommendation Track http://www.w3.org/2006/07/SWD/

SKOS Use Cases and Requirements

First Working Draft Published (2007-05-16) http://www.w3.org/TR/skos-ucr/

New SKOS Web Site

http://www.w3.org/2004/02/skos/

Features Identifying concepts URIs for unambiguous global identity and reference Labelling concepts e.g. lexical labels, symbolic labels, preferred, alternative, hidden … Describing & documenting concepts e.g. definition, example, scope note, change note, editorial note … Relating concepts e.g. broader, narrower, related … Grouping concepts e.g. concept schemes, support for ‘node labels’ … Subject Indexing e.g. subject of a document, primary subject … Multilingual Extensible

Identifying concepts

URIs for unambiguous global identity and reference

Labelling concepts

e.g. lexical labels, symbolic labels, preferred, alternative, hidden …

Describing & documenting concepts

e.g. definition, example, scope note, change note, editorial note …

Relating concepts

e.g. broader, narrower, related …

Grouping concepts

e.g. concept schemes, support for ‘node labels’ …

Subject Indexing

e.g. subject of a document, primary subject …

Multilingual

Extensible

Concept Defined as: An abstract idea or notion; a unit of thought. I.e. A unit of meaning. The fundamental unit of a concept scheme.

Defined as: An abstract idea or notion; a unit of thought.

I.e. A unit of meaning.

The fundamental unit of a concept scheme.

Concepts

Concept Scheme Defined as: A set of concepts, optionally including statements about semantic relationships between those concepts. A … thesaurus classification scheme taxonomy terminology subject heading system [other type of controlled vocabulary] … is a concept scheme.

Defined as: A set of concepts, optionally including statements about semantic relationships between those concepts.

A …

thesaurus

classification scheme

taxonomy

terminology

subject heading system

[other type of controlled vocabulary]

… is a concept scheme.

Lexical Labelling SKOS lexical labelling properties A set of properties for associating concepts with lexical representations (i.e. terms) prefLabel altLabel hiddenLabel

SKOS lexical labelling properties

A set of properties for associating concepts with lexical representations (i.e. terms)

prefLabel

altLabel

hiddenLabel

Lexical Labelling

Symbolic Labelling SKOS symbolic labelling properties A set of properties for associating concepts with symbolic representations (i.e. symbolic ‘names’) prefSymbol altSymbol

SKOS symbolic labelling properties

A set of properties for associating concepts with symbolic representations (i.e. symbolic ‘names’)

prefSymbol

altSymbol

Symbolic Labelling

Semantic Relations SKOS semantic relation properties A basic set of properties for asserting relationships of meaning between concepts. broader narrower related

SKOS semantic relation properties

A basic set of properties for asserting relationships of meaning between concepts.

broader

narrower

related

Semantic Relations

Semantic Relations

Documentation Properties SKOS documentation properties A set of properties for associating concepts with human-readable documentation. changeNote definition editorialNote example historyNote privateNote publicNote scopeNote

SKOS documentation properties

A set of properties for associating concepts with human-readable documentation.

changeNote

definition

editorialNote

example

historyNote

privateNote

publicNote

scopeNote

Documentation Properties

Documentation Properties

Subject Indexing SKOS subject indexing properties Set of property extensions to the dc:subject property for asserting relationships between information resources and concepts. isPrimarySubjectOf primarySubject isSubjectOf subject subjectIndicator

SKOS subject indexing properties

Set of property extensions to the dc:subject property for asserting relationships between information resources and concepts.

isPrimarySubjectOf

primarySubject

isSubjectOf

subject

subjectIndicator

Subject Indexing

Grouping SKOS Grouping Properties A set of classes and properties for organizing Concepts Classes: Collection orderedCollection Concept Properties: member memberList

SKOS Grouping Properties

A set of classes and properties for organizing Concepts

Classes:

Collection

orderedCollection

Concept Properties:

member

memberList

Thesaurus Example Term: Economic cooperation Used For: Economic co-operation Broader terms: Economic policy Narrower terms: Economic integration, European economic cooperation, European industrial cooperation, Industrial cooperation Related terms: Interdependence Scope Note: Includes cooperative measures in banking, trade, industry etc., between and among countries. From UK Archival Thesaurus …

Term: Economic cooperation

Used For: Economic co-operation

Broader terms: Economic policy

Narrower terms: Economic integration, European economic cooperation, European industrial cooperation, Industrial cooperation

Related terms: Interdependence

Scope Note: Includes cooperative measures in banking, trade, industry etc., between and among countries.

Thesaurus Example

Thesaurus Example <rdf:RDF xmlns:rdf=&quot;http://www.w3.org/1999/02/22-rdf-syntax-ns#&quot; xmlns:rdfs=&quot;http://www.w3.org/2000/01/rdf-schema#&quot; xmlns:skos=&quot;http://www.w3.org/2004/02/skos/core#&quot;> <skos:Concept rdf:about=&quot;http://www.ukat.org.uk/thesaurus/concept/1750&quot;> <skos:prefLabel>Economic cooperation</skos:prefLabel> <skos:altLabel>Economic co-operation</skos:altLabel> <skos:scopeNote>Includes cooperative measures in banking, trade, industry etc., between and among countries.</skos:scopeNote> <skos:broader rdf:resource=&quot;http://www.ukat.org.uk/thesaurus/concept/4382&quot;/> <skos:narrower rdf:resource=&quot;http://www.ukat.org.uk/thesaurus/concept/2108&quot;/> <skos:narrower rdf:resource=&quot;http://www.ukat.org.uk/thesaurus/concept/9505&quot;/> <skos:narrower rdf:resource=&quot;http://www.ukat.org.uk/thesaurus/concept/15053&quot;/> <skos:narrower rdf:resource=&quot;http://www.ukat.org.uk/thesaurus/concept/18987&quot;/> <skos:related rdf:resource=&quot;http://www.ukat.org.uk/thesaurus/concept/3250&quot;/> <skos:inScheme rdf:resource=&quot;http://www.ukat.org.uk/thesaurus&quot;/> </skos:Concept> </rdf:RDF> RDF/XML serialisation …

Flexible ‘ Pic’n’mix SKOS with other vocabs, e.g. Dublin Core, RSS, FOAF …

‘ Pic’n’mix SKOS with other vocabs, e.g. Dublin Core, RSS, FOAF …

Extensible Extended labelling properties e.g. common name, scientific name Extended concept types e.g. AAT’s fundamental facets Extended documentation properties e.g. MARC21, DDC Extended semantic relation properties e.g. broader instantive, broader generic, broader partitive Can cope with specialised requirements without compromising interoperability

Extended labelling properties

e.g. common name, scientific name

Extended concept types

e.g. AAT’s fundamental facets

Extended documentation properties

e.g. MARC21, DDC

Extended semantic relation properties

e.g. broader instantive, broader generic, broader partitive

Can cope with specialised requirements without compromising interoperability

NSDL Metadata Registry The NSDL Registry is intended to provide a complete vocabulary development and management environment for development of vocabularies . Services are primarily directed at vocabulary owners and include provisions for: managing access and editing rights for groups of vocabulary maintainers maintaining individual vocabularies import and management of existing vocabularies , with and without existing URIs namespace management and maintenance services providing permanent URIs registered users to receive notifications of changes to vocabularies to which they have subscribed content negotiation for retrieval of registered vocabularies in various formats, currently RDF/XML (rdf), XHTML (html), and XML Schema (xsd) content negotiation and resolution services for registered vocabularies in non-registry namespaces (in alpha) …

The NSDL Registry is intended to provide a complete vocabulary development and management environment for development of vocabularies . Services are primarily directed at vocabulary owners and include provisions for:

managing access and editing rights for groups of vocabulary maintainers maintaining individual vocabularies

import and management of existing vocabularies , with and without existing URIs

namespace management and maintenance services providing permanent URIs

registered users to receive notifications of changes to vocabularies to which they have subscribed

content negotiation for retrieval of registered vocabularies in various formats, currently RDF/XML (rdf), XHTML (html), and XML Schema (xsd)

content negotiation and resolution services for registered vocabularies in non-registry namespaces (in alpha)

…

NSDL Metadata Registry … controlled concept editing and maintenance using SKOS properties controlled insertion of reciprocal relationships between concepts controlled mapping of relationships between concepts in different vocabularies . Concept property-level change history management vocabulary- and concept-level version management (in alpha) multilingual vocabulary maintenance SKOS validation by user input constraint and validation of imported vocabularies search and browse for concepts by label

…

controlled concept editing and maintenance using SKOS properties

controlled insertion of reciprocal relationships between concepts

controlled mapping of relationships between concepts in different vocabularies .

Concept property-level change history management

vocabulary- and concept-level version management (in alpha)

multilingual vocabulary maintenance

SKOS validation by user input constraint and validation of imported vocabularies

search and browse for concepts by label

Description of entire vocabulary as a collection of concepts Links to Concepts, History, Versions Default status and Language URI for the vocabulary itself (includes token) Links to Users Links to XML schema and RDF encoding NSDL Metadata Registry: Example Concept Scheme registration

Description of entire vocabulary as a collection of concepts

Links to Concepts, History, Versions

Default status and Language

URI for the vocabulary itself (includes token)

Links to Users

Links to XML schema and RDF encoding

NSDL Metadata Registry: Example Concept registration Required Preferred Label Multi-language support Permanent URI for the Concept Support for status Links to other Concept properties Link to RDF fragment

Required Preferred Label

Multi-language support

Permanent URI for the Concept

Support for status

Links to other Concept properties

Link to RDF fragment

NSDL Metadata Registry: Example Concept Property editing Guided selection of Concept properties

Guided selection of Concept properties

NSDL Metadata Registry: Example Concept Property editing Guided selection of Concept properties Guided selection of related concept when using a “relationship” property

Guided selection of Concept properties

Guided selection of related concept when using a “relationship” property

NSDL Metadata Registry: Example Concept Property editing Guided selection of Concept properties Guided selection of related concept when using a “relationship” property Support for property-level status Links to other Concept properties

Guided selection of Concept properties

Guided selection of related concept when using a “relationship” property

Support for property-level status

Links to other Concept properties

NSDL Metadata Registry: User Management Users and rights can be associated with specific Vocabularies Vocabulary admins can assign Users and editorial rights Any user who creates a new Vocabulary is automatically the admin for it

Users and rights can be associated with specific Vocabularies

Vocabulary admins can assign Users and editorial rights

Any user who creates a new Vocabulary is automatically the admin for it

NSDL Metadata Registry: HTTP Publishing Implements http content negotiation (W3C ‘Cookbook’) based on W3C TAG httpRange-14 for document retrieval See the Recipes http://www.w3.org/TR/swbp-vocab-pub/ and http://norman.walsh.name/2005/06/19/httpRange-14 We use ‘slash’ (/) URIs instead of ‘hash’ (#) Hash URIs must return the entire document when any fragment (identified by #) is requested We think this is impractical for information resources

Implements http content negotiation (W3C ‘Cookbook’) based on W3C TAG httpRange-14 for document retrieval

See the Recipes http://www.w3.org/TR/swbp-vocab-pub/ and http://norman.walsh.name/2005/06/19/httpRange-14

We use ‘slash’ (/) URIs instead of ‘hash’ (#)

Hash URIs must return the entire document when any fragment (identified by #) is requested

We think this is impractical for information resources

NSDL Metadata Registry: HTTP Publishing Also implements ‘extension’-based document retrieval… A request for a document of the type ‘application/rdf+xml’ located at… http:// metadataregistry.org/uri/NSDLEdLvl redirects to… http://metadataregistry.org/uri/NSDLEdLvl.rdf Which returns…

Also implements ‘extension’-based document retrieval…

A request for a document of the type ‘application/rdf+xml’ located at… http:// metadataregistry.org/uri/NSDLEdLvl

redirects to… http://metadataregistry.org/uri/NSDLEdLvl.rdf

Which returns…

NSDL Metadata Registry: Versioning Time-slice versioning Saves the state of the Scheme whenever a Concept property is added or changed RESTful interface Scheme or Concept state can be retrieved by appending an encoded UTC Timestamp to URI… e.g. scheme current trunk http://metadataregistry.org/NSDLEdLvl e.g. scheme as of “2007-01-26T01:15:38.000Z” http://metadataregistry.org/NSDLEdLvl/2007-01-26T01%3A15%3A38.000Z Only Concept properties that have ‘Published’ state Provides a permanent URI for Scheme/Concept at any given point in time -- helps minimize ‘version churn’

Time-slice versioning

Saves the state of the Scheme whenever a Concept property is added or changed

RESTful interface

Scheme or Concept state can be retrieved by appending an encoded UTC Timestamp to URI…

e.g. scheme current trunk http://metadataregistry.org/NSDLEdLvl

e.g. scheme as of “2007-01-26T01:15:38.000Z” http://metadataregistry.org/NSDLEdLvl/2007-01-26T01%3A15%3A38.000Z

Only Concept properties that have ‘Published’ state

Provides a permanent URI for Scheme/Concept at any given point in time -- helps minimize ‘version churn’

NSDL Metadata Registry: Versioning Named versions Identifies an ‘official’ version by naming a time-slice Vocabulary admin may apply a version name to any time-slice in the past RESTful interface Scheme or Concept state can be retrieved by appending a version to URI… e.g. scheme as of “2007-01-26T01:15:38.000Z” http://metadataregistry.org/NSDLEdLvl/2007-01-26T01%3A15%3A38.000Z permanently named “Release Version 1.2” http://metadataregistry.org/NSDLEdLvl/release_version_1.2 Currently no support for editable branches

Named versions

Identifies an ‘official’ version by naming a time-slice

Vocabulary admin may apply a version name to any time-slice in the past

RESTful interface

Scheme or Concept state can be retrieved by appending a version to URI…

e.g. scheme as of “2007-01-26T01:15:38.000Z” http://metadataregistry.org/NSDLEdLvl/2007-01-26T01%3A15%3A38.000Z permanently named “Release Version 1.2” http://metadataregistry.org/NSDLEdLvl/release_version_1.2

Currently no support for editable branches

SWDWG Semantic Web Deployment Working Group http://w3.org/2006/07/SWD/ Began: 10 October 2006 Lifetime: 20 months Chairs: Guus Schreiber Thomas Baker

Semantic Web Deployment Working Group

http://w3.org/2006/07/SWD/

Began: 10 October 2006

Lifetime: 20 months

Chairs:

Guus Schreiber

Thomas Baker

SWDWG: SKOS Deliverables and Schedule http://www.w3.org/2006/07/SWD/wiki/Deliverables SKOS Use Cases and Requirements SKOS Test Cases SKOS Semantics (Normative Specification) SKOS Primer SKOS Vocabulary Overview March 2008: SKOS Proposed Recommendation

Deliverables and Schedule

http://www.w3.org/2006/07/SWD/wiki/Deliverables

SKOS Use Cases and Requirements

SKOS Test Cases

SKOS Semantics (Normative Specification)

SKOS Primer

SKOS Vocabulary Overview

March 2008: SKOS Proposed Recommendation

SWDWG: SKOS Use Cases & Requirements Analysis Public Working Draft (May 2007) http://www.w3.org/TR/skos-ucr/ Do you have a use case or requirements/issues for SKOS? We’d still like to know… mailto://public-swd-wg@w3.org/

Use Cases & Requirements Analysis

Public Working Draft (May 2007) http://www.w3.org/TR/skos-ucr/

Do you have a use case or requirements/issues for SKOS?

We’d still like to know… mailto://public-swd-wg@w3.org/

SWDWG: SKOS Current Use Cases Dutch and French national libraries -- an integrated view to medieval illuminated manuscripts Bio-zen ontology framework for representing scientific discourse in life science The FAO AIMS project – a semantic search service across mapped multilingual thesauri in the agriculture domain BAE Systems -- The Product Life Cycle Support (PLCS) application CHOICE@CATCH ranking of candidate terms for description of radio and TV programs BIRNLex: a lexicon for neurosciences Radlex: a lexicon for radiology NSDL Metadata Registry

Dutch and French national libraries -- an integrated view to medieval illuminated manuscripts

Bio-zen ontology framework for representing scientific discourse in life science

The FAO AIMS project – a semantic search service across mapped multilingual thesauri in the agriculture domain

BAE Systems -- The Product Life Cycle Support (PLCS) application

CHOICE@CATCH ranking of candidate terms for description of radio and TV programs

BIRNLex: a lexicon for neurosciences

Radlex: a lexicon for radiology

NSDL Metadata Registry

SWDWG: SKOS Selected Open Issues Typed relationships between labels SKOS allows the expression of semantic relationships (broader, related) between concepts. It also allows relationships between concepts and labels (prefLabel, altLabel). Issue: There is nothing in SKOS to capture links between labels themselves.

Typed relationships between labels

SKOS allows the expression of semantic relationships (broader, related) between concepts.

It also allows relationships between concepts and labels (prefLabel, altLabel).

Issue:

There is nothing in SKOS to capture links between labels themselves.

SWDWG: SKOS Selected Open Issues Basic Label Semantics Issues Can a resource have two “preferred labels”? Can a label be both &quot;preferred&quot; and “alternative? for the same resource? If a label is “hidden”, can it also be “preferred” or “alternative” for the same resource?

Basic Label Semantics Issues

Can a resource have two “preferred labels”?

Can a label be both &quot;preferred&quot; and “alternative? for the same resource?

If a label is “hidden”, can it also be “preferred” or “alternative” for the same resource?

SWDWG: SKOS Selected Open Issues Grouping in Concept Hierarchies Thesaurus standards describe the use of “node labels” for convenient grouping and display. Issue: The current grouping support in SKOS (called “Collections”) introduces logical inconsistencies into the SKOS spec. this is bad And more than a few others… http://www.w3.org/2006/07/SWD/track/issues

Grouping in Concept Hierarchies

Thesaurus standards describe the use of “node labels” for convenient grouping and display.

Issue:

The current grouping support in SKOS (called “Collections”) introduces logical inconsistencies into the SKOS spec.

this is bad

And more than a few others… http://www.w3.org/2006/07/SWD/track/issues

SWDWG: SKOS So we’ve definitely got issues! http://www.w3.org/2006/07/SWD/track/issues A final word from Alistair Miles… “ Bring out the unsolved stuff, don't hide any of the difficulties.” “ N.B. interoperability with ISO11179 is a requirement and a big issue for SKOS, so let everybody know we're going to need help there.” “ Take home message: lots of interesting challenges and issues, really want to hear from registry community!”

So we’ve definitely got issues!

http://www.w3.org/2006/07/SWD/track/issues

A final word from Alistair Miles…

“ Bring out the unsolved stuff, don't hide any of the difficulties.”

“ N.B. interoperability with ISO11179 is a requirement and a big issue for SKOS, so let everybody know we're going to need help there.”

“ Take home message: lots of interesting challenges and issues, really want to hear from registry community!”

Links SKOS Homepage http://www.w3.org/2004/02/skos/ SKOS Guide http://www.w3.org/TR/swbp-skos-core-guide SKOS Vocabulary Specification http://www.w3.org/TR/swbp-skos-core-spec SWD-WG Home Page http://www.w3.org/2006/07/SWD/ SWD-WG Mailing list mailto:public-swd-wg@w3.org http://lists.w3.org/Archives/Public/public-swd-wg/ NSDL Metadata Registry http://metadataregistry.org Please play in our sandbox! http://sandbox.metadataregistry.org The Registry blog (gotta have one) http://metadataregistry.org/blog Jon Phipps mailto:jphipps@madcreek.com Thanks for listening 

SKOS Homepage

http://www.w3.org/2004/02/skos/

SKOS Guide

http://www.w3.org/TR/swbp-skos-core-guide

SKOS Vocabulary Specification

http://www.w3.org/TR/swbp-skos-core-spec

SWD-WG Home Page

http://www.w3.org/2006/07/SWD/

SWD-WG Mailing list

mailto:public-swd-wg@w3.org

http://lists.w3.org/Archives/Public/public-swd-wg/

NSDL Metadata Registry

http://metadataregistry.org

Please play in our sandbox!

http://sandbox.metadataregistry.org

The Registry blog (gotta have one)

http://metadataregistry.org/blog

Jon Phipps

mailto:jphipps@madcreek.com

Thanks for listening 