Digital Libraries and the Semantic Web

Eric Miller
em@w3.org
W3C Semantic Web Activity Lead

5th European Conference on Research and Advanced Technology for Digital Libraries, September 4-9 2001, Darmstadt, Germany

Slides available at:
http://www.w3.org/2001/09/06-ecdl/

Overview

• Overview of the W3C Semantic Web Activity
  • Background, Structure, Goals and Principles
• Enabling Standards and Technologies
  • RDF, RDF Schema, Web Ontologies, Future work
• Semantic Web Advanced Development
  • Overview, Goals, Objectives
  • Highlights (Demonstrations)
• Digital Libraries
  • Relationships between Semantic Web and Digital Libraries
  • Examples
• Future Directions
  • Lessons Learned
  • Where we're going from here
• Open Discussion

The Semantic Web: What is it?

• Many things to many people...

The Semantic Web

• An interesting bed-time story...

The Semantic Web: The original web realized

• The original proposal of the WWW from 1989 included a figure showing how information about a Web of relationships amongst named objects could unify a number of information management tasks.
  • Information Management: A Proposal, Tim Berners-Lee, CERN, March 1989, May 1990, http://www.w3.org/History/1989/proposal.html

The Current Web

The Semantic Web - A Simple Extension to the Current Web

W3C Semantic Goals

• Realizing the full potential of the Web
• Making it cost-effective for people to effectively record their knowledge.
• Focus on machine consumption.
  • "The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation." -- Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web
  • "The bane of my existence is doing things that I know the computer could do for me." -- Dan Connolly, The XML Revolution
• Ultimate goal - the design of enabling technologies to support machine facilitated global knowledge exchange

W3C Semantic Web Activity - Structure

The Semantic Web Activity

• Semantic Web is part of the W3C Technology and Society Domain
• Managing the Development Enabling Standards and Technologies
  • RDF Resource Description Framework
  • The RDF Core Working Group
  • The Web Ontology Working Group
• Supporting Advanced Development
  • Explore pre-competitive, prototype development for supporting the Semantic Web
• Investing in Education and Outreach
  • Clarification of design, goals, implementation guidelines
  • Position papers, Articles, Presentations, Tutorials, Tools

W3C Semantic Web Activity - Approach to Deployment

• Establish guiding architectural principles
• Facilitate the design of enabling standards and technologies
• Focus on short term deployment
• Eye toward longer term research issues
• Understand policy implications
• Foster an environment for effective cooperation and collaboration
• A lot of hard work
• And a bit of luck

Semantic Web Principles

Everything Identifiable is on the Semantic Web

• All resources have identy
• People, places, and things in the physical world will have online representations identified by Uniform Resource Identifiers.
• URI's facilitate effective integration, active participation and be contextualized in the Semantic Web.

Semantic Web Principles

Partial Information

• The Web is unbounded.
  • The original design of the Web differed from traditional hypertext systems in sacrificing link integrity for scalability.
• The Semantic Web it unbounded.
  • Anyone can say anything about anything.
• There will always be more to discover.

Semantic Web Principles

Web of Trust

• All statements found on the Web occur in some context.
• Applications need this context in order to evaluate the trustworthiness of the statements.
• The machinery of the Semantic Web does not assert that all statements found on the Web are "true".
• Truth - or more pragmatically, trustworthiness - is evaluated by each application that processes the information found on the Web.

Semantic Web Principles

Evolution

• The Semantic Web must allow the independent work of diverse communities to be combined effectively.
• Support the ability to add new information without insisting that the old be modified.
• Provide communities the ability to resolve ambiguities and clarify inconsistencies.
• Semantic Web must be based on descriptive conventions that can expand as human understanding expands.

Semantic Web Principles

Minimalist Design

• Make the simple things simple, and the complex things possible.
• Standardize nor more than is necessary.
• More than the sum of the parts

Semantic Web

Building on proven ideas

• Combines RDF, XML, Xlink, hypertext and metadata approaches to linked data
• Enable simple applications now that plan for future complexity (eg. Dublin Core, RSS, PRISM, MusicBrainz)
• Focussed on general principles of Web automation and data aggregation

Architectural aims

• Define a convention for applications that exchange metadata on the Web
• XML used for "serialization syntax"
• Enable vocabulary semantics to be defined by communities of expertise, not W3C
• Provide for the fine-grained mixing of diverse metadata

Layer Cake

RDF Core Working Group

• RDF provides a common framework for representing metadata across many applications.
• Implementor feedback concerning the RDF Model and Syntax Recommendation points to the need for a number of fixes, clarifications and improvements to the specification of RDF's abstract model and XML syntax.
• Also tasked to complete the work on RDF vocabulary description present in the RDF Schema Candidate Recommendation.
• Provide an account of the relationships between the basic components of RDF (Model, Syntax, Schema) and the larger XML family of recommendations.
• Brian McBride <brian_mcbride@hp.com> HP Labs and Dan Brickley <danbri@w3.org> (W3C/ILRT) chairs

Web Ontology Working Group

• Designed to standardize means for defining ontolgies that can be used on the Web.
• Builds on RDF Schema (classes and subclasses, properties and subproperties)
• Extends these constructs to allow more complex relationships between entities (e.g.):
  • limit the properties of classes with respect to number and type
  • means to infer that items with various properties are members of a particular class
  • a well-defined model for property inheritance
• Input from the DAML+OIL work supported by DARPA's DAML Initiative
• James Hendler <hendler@cs.umd.edu> chair

Semantic Web Public

• Semantic Web / RDF Interest Group
  • Dan Brickley <danbri@w3.org> (W3C/ILRT) chair
  • a forum for W3C Members and non-Members to discuss innovative applications of RDF and the Semantic Web.
• RDF Logic
  • detailed technical discussion of all approaches to the use of classical logic on the Web for the representation of data such as inference rules, ontologies, and complex schemata.
• RDF Calendar
  • public forum for discussion of RDF-based calendar and group scheduling systems
• Annotation and Collaboration
  • public forum for discussion of RDF-based annotation and collaboration systems

Semantic Web Advanced Development

Goals

• Explore pre-competitive, prototype ideas
• Venue for liaison with research community;
• Inform, be informed, nudge, be nudged
• Testbed for early implementations of Working Drafts
• Collaborative development environment for the Team and Members to explore ideas together
• Stimulate the development of more Semantic Web infrastructure components

Areas of Development

• Developers Tools
• Resource Description
• Annotation, Collaboration, and Web of Trust
• Access Control Rules, Logic and Proof
• Calendaring and Scheduling
• Work-flow and Dependency Tracking
• Transformation and Extraction Utilities
• Integration with XML infrastructure

Advanced Development - Annotation, Collaboration, and Web of Trust

• Annotea: Collaborative annotation system
• Annotations are stored on annotation servers as metadata and presented to the user by a client capable of understanding this metadata and capable of interacting with an annotation server with the HTTP service protocol.
• Clients include editor/browser (Amaya) and browser plug-ins (Annozilla)
• HTTP-based RDF store
• Testbed for other collaboration support tools (e.g. peer review, web of trust, recomender services, WAI, etc.)
• W3C Team members: Marja-Riitta Koivunen, Ralph Swick, Jose Kahan, Eric Prud'hommeaux

Advanced Development - Workflow

Scenario (a): W3T requirement to automate creation, maintenance of W3C TR Page. Solution: W3C Working Group Chairs make assertions that a document is at a particular status by submitting announcement to list.

    <TRDocument rdf:about="http://www.w3.org/TR/xmlbase/">
        <date>2001-07-09</date>
        <editor rdf:parseType="Resource">
            <contact:fullName>Jonathan Marsh</contact:fullName>
            <contact:mailbox rdf:resource="mailto:jmarsh@microsoft.com"/>
        </editor>
        <of rdf:parseType="Resource">
            <rdf:type rdf:resource="http://www.w3.org/2001/04/roadmap/org#WorkingGroup"/>
            <contact:mailbox rdf:resource="mailto:w3c-xml-linking-wg@w3.org"/>
        </of>
        <status rdf:parseType="Resource">
            <rdfs:label>Working Draft</rdfs:label>
            <level rdf:resource="http://www.w3.org/2001/06/swamt/vocab#Recommendation"/>
        </status>
        <title>XML Base</title>
    </TRDocument>

Advanced Development - Workflow (Announce)

Graphical display of formalized announcement.

Advanced Development - Workflow (Announce, Org Merge)

Document information associated with a particular working group is merged with W3C Organizational information.

    <Activity>
        <name>Extensible Markup Language (XML) Activity</name>
        <contact:homePage rdf:resource="http://www.w3.org/XML/Activity"/>
        <includes>
            <WorkingGroup>
                <name>XML Linking WG</name>
                <contact:homePage rdf:resource="http://www.w3.org/XML/Group/Linking"/>
                <contact:mailbox rdf:resource="mailto:w3c-xml-linking-wg@w3.org"/>
            </WorkingGroup>         
        </includes>
    </Activity>

Advanced Development - Workflow (Announce, Org Merge)

Document information associated with a particular working group is merged with W3C Organizational information.

Recommendations
  ...
  Extensible Markup Language (XML) Activity
   ...
   XML Base, 2001-07-09, Johnathan Marsh, (XML Linking Working Group)

Advanced Development - Workflow (Announce, Org, Contact Merge)

Scenario (b): W3C AC Representatives need to identify status of all documents whose parent organization has sponsored working group members. Solution (a): Document information associated with a particular working group is merged with W3C Contact information.

Advanced Development - Workflow (Announce, Org, Contact, Membership Merge)

Solution (b): Document information associated with a particular working group is merged with W3C Contact information and then Membership information.

Future Directions of the Activity

Activity

• Understanding relationships to similar technologies, explore possibilies for future convergence.
  • Clearer ties among RDF and XML family is still required.
  • Better understanding between Semantic Web and Web Services is required.
• IST EU Semantic Web Initiative

Enabling Standards and Technologies

• Query and Rules

Advanced Development

• Clarity of goals and missions
• More task forces
• Integration with tools to support more effective means of distributed collaborations
• Cooperation with other groups working on similar issues (e.g. Microsoft .Net, Sun's One Framework, open source .NET, DotGNU, etc.)

Education and Outreach

• Guidlines, Demonstrations, Position papers, Articles, Presentations, Tutorials, Tools

Digital Libraries and the Semantic Web

• Conference theme: convergence of digital libraries, museums and archives as memory organizations.
• Personal theme: convergence of enabling technologies neccessary to support conference theme.
• More specifically, identification of technical and social areas of overlap between Semantic Web and Digital Libraries.
• Help faciliate these memory organizations as key foundations for supporting the Semantic Web

Advanced Development - DSpace

• Semantic Web Advanced Development collaboration with the DSpace project
  • Dspace is a joint project of MIT Libraries and HP to develop a flexible digital archive designed capture and distribute the intellectual output of MIT
• Explore practical deployment issues for Semantic Web and metadata applications in a digital library context.
  • Existing RDF data stores and examine effective techniques for storing complex metadata in a variety of systems.
  • expected to field-test proposals (such as the DAML RDF/XML datatyping proposal) that are under consideration by other W3C groups.
  • demonstrate web aggregation services based on information syndication technologies such as RSS and OAI
• Public discussion archive is avaliable

Formalized facilities for supporting ontology merging

Modeling dmoz

Dmoz and My Favorites

Merging Dmoz and My Favorites

Formalized means for expressing simple vocabularies

Supporting Graphical Model

Conclusions

• Supporting simple to complex systems using common infrastructure
• Optimal data reuse in networked environment
• More similarites than differences
• Perhaps not surprising since semantic web technology was greatly influneced by Digital Library communities
• More formal understanding of these relationships however are still required
• Great opportunity for the Digital Library community to help shape the Semantic Web

More information

• Semantic Web Home Page: http://www.w3.org/2001/sw/
• Semantic Web Advanced Development Home Page: http://www.w3.org/2000/01/sw/
• RDF Home Page: http://www.w3.org/rdf/
• Ok, how can I get involved?
  • (a) JOIN W3C!
  • (b) see (a)
  • (c) Semantic Web Interest Groups
    • Semantic Web / RDF Interest Group http://www.w3.org/RDF/Interest
    • Semantic Web / RDF IRC irc://openprojects.net/#rdfig