Lee Iverson - How does the web connect content?

©2008, Lee Iverson <[email protected]> UBC Dept. of ECE

Semantic Pragmatics

Lee Iverson

UK Museums and the Web


Connecting

Museum Museum

Users Users

??? ???


Why to connect?

• Referral– Let users know about other museums

• Enhancement– Improve information about your collection

• Personalization– Improve relevance to each user

• …


The Powerhouse


Becoming Connected

• Expose own data

• Find other data

• Integrate

• Engage with users


Exposing Data

• Museums manage structured, authoritative data about collections

but• Museum web sites are dominated by

presentation and control

• Results:– Museum web data is hermetically sealed– User experience is completely controlled


Exposing Data

• Give it away as structured data– Must decide private/public boundary

• Creative commons licensing

– Easy to do via web (hint: XML or RDF)

• Benefits:– Aggregation possibilities

• Museum to museum links possible

– Consumers can repurpose data– New uses means new customers


How?

• Add links to structure from:– Main page – Individual pages

• Objects and exhibits

– Visible links?– Meta links! (e.g. RSS)

• Standardize– Which standards?– Which vocabularies?


Standards Strategy

Standard = agreement between min. 2 parties to do something in same way

Pragmatics:– Use existing standards as much as possible – Never standardize more than minimum

• That which is necessary for essential functionality

– Never standardize vaporware– Recognize defacto standards rather than create

new ones


Is this the Semantic Web?

• Maybe– Meaning vs. Presentation– Machine vs. Human

• Maybe not– Where is the meaning?– Where is the reasoning?


Berners-Lee

“I have a dream for the Web [in which computers] become capable of analyzing all the data on the Web – the content, links, and transactions between people and computers. A ‘Semantic Web’, which should make this possible, has yet to emerge, but when it does, the day-to-day mechanisms of trade, bureaucracy and our daily lives will be handled by machines talking to machines. The ‘intelligent agents’ people have touted for ages will finally materialize.”

– Tim Berners-Lee, 1999


Syntax vs. Semantics

• In a certain sense structure and vocabulary is the semantics

• Semantics: – Ability to interpret– Repurposability– Mirroring human interpretation


Finding Data

• Linking to other museums and sites…

• Spider and scrape– Tools: Calais?– Unreliable, expensive, needs moderation

• Rely on structured data– RSS or Atom– You show me yours…?


Integration

• Relate your content to theirs– Relate structure– Relate vocabulary– Relate context

• It is possible!– Reciprocal Research Network– Straight from CMS– http://rrnpilot.org


Data for Integration

XML• Information model• One syntax• Schema from

structure• Integration by

structural integration

RDF• Data model• A few syntaxes• Schema from

vocabulary• Integration by

reference


RDFa

RDF in XHTML:– Best of both worlds– Microformat-like attributes on XHTML

content– Need to match XML structure to RDF

classes– Ordinary web pages can be “data web”

pages


RDF

• Resource description framework• Metadata language

– Simple, unambiguous data model– Model built on reference, so statements

can be detached from their referents

• Foundation for:– RSS – RDF Site Summary– DAML+OIL and OWL (Semantic Web)


RDF Model

• RDF document is set of statements• Statement is triple:

– Subject – a URI reference– Property – a URI reference– Object – a value (may be URI)

• RDFS (RDF Schema)– Restrict subject/object values based on property– Property URI contains description of constraints


RDF Example

1. @prefix dc: <http://purl.org/dc/elements/1.1/> .

2. @prefix foaf: <http://xmlns.com/foaf/0.1/> .

3. <http://example.org/> dc:creator _:b .

4. _:b foaf:name "Bob" .

“A person named Bob is the creator of http://example.org”

http://example.org _:bdc:creator

“Bob”

foaf:name


RDF Schema Example<rdf:Property rdf:about="http://xmlns.com/foaf/0.1/name" rdfs:label="name" rdfs:comment="A name for some thing."> <rdfs:range rdf:resource="http://www.w3.org/2000/01/rdf-schema#Literal"> </rdfs:range> <rdfs:isDefinedBy rdf:resource="http://xmlns.com/foaf/0.1/"> </rdfs:isDefinedBy> <rdfs:subPropertyOf rdf:resource= "http://www.w3.org/2000/01/rdf-schema#label"> </rdfs:subPropertyOf></rdf:Property>


What About Semantics?

DAML+OIL or OWL provide:– Vocabulary of basic properties– Mappings from these properties to formal

semantics– Language for defining new, semantically

well-defined properties– Language for expressing logical inferences

that can be made within vocabulary


What is an Ontology?

Formal (but uninformative):“A specification of a conceptualization”

Informal“A shared vocabulary designed to support the communication

of the meaning of a certain class of resources”“An attempt to make semantics of a body of knowledge more

explicit”

Technical:“A vocabulary and logical inference statements expressed in a

formal language (e.g. OWL) for describing a set of resources”


A Simple Ontology

Cat DogCheetah

Species

category-typecategory-type category-type

Feline Canine

Mammal

kind-of kind-of

kind-ofkind-ofkind-of

disjointdisjoint

disjoint

hates


McBride’s 4 Stepsfor Widespread Adoption

• Promote practical applications

• Develop applications now

• Simple and tolerant of error

• Open source


Be Wary

• Berners-Lee’s “Semantic Web” doesn’t yet exist– Nothing comes for free– Landay’s AI completeness theory

• But…– The data web is useful– We can go there now!

Technology

Lee Iverson - How does the web connect content?