MOAT: From Tagging to Semantic Web - WWW2008, Dev Track, 2008-04-25, Beijing1

MOAT: From Tagging to Semantic WebAlexandre Passant

WWW2008, Dev Track, 2008-04-25, Beijing

Electricité de France R&D, Clamart, FranceLaLIC, Université Paris-Sorbonne, France

MOAT: From Tagging to Semantic Web - WWW2008, Dev Track, 2008-04-25, Beijing2

Tagging is cool ...

• A widely-used practice• Pictures, bookmarks, videos, blog posts, e-mails, music ...

• Various advantages• No pre-defined schema• Emergent user-based vocabulary• Browsing capabilities• Social aspect

MOAT: From Tagging to Semantic Web - WWW2008, Dev Track, 2008-04-25, Beijing3

... but has various limitations

• Ambiguity• One tag for different concepts• Acronyms, homonyms …

• Apple - Fruit ? Company ?• Heterogeneity

• Different tags for the same concept• Case-variation, synonymy, internationalization …

• Beijing, Pekin - The same city• Lack of organisation

• No relationship between tags• SemWeb, RDF, SPARQL - How to find one tag from another ?

“A folksonomy represents simultaneously some of the best and worst in the organization of information” Mathes (2004)

MOAT: From Tagging to Semantic Web - WWW2008, Dev Track, 2008-04-25, Beijing4

Heterogeneity

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Ambiguity

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How to solve this

• Tags are just keywords• They do not care any machine-readable information

• Computers cannot understand what the users have in mind when tagging content and retrieving it

• “I’m using the tag ‘Paris’ and I mean the French city”• “Please find all the pictures tagged ‘apple’ as a fruit, not a company” • “Please find all bookmarks about the Semantic Web technology, whatever

people tagged it”• The Semantic Web provides URIs to define things with a well-given semantic, rather than using keywords

• “The Semantic Web is not a separate Web but an extension of the current one, in which information is given well-defined meaning, better enabling computers and people to work in cooperation” Berners-Lee et al. (2001)

• A graph layer upon the documents layer, using RDF

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Tags and the Semantic Web

• The Tag Ontology provides a way to represent tags and tagging actions in the Semantic Web

• tags:Tag rdfs:subClassOf skos:Concept

• tags:Tagging and tags:RestrictedTagging• SCOT - Social Semantic Cloud Of Tags - provides a way to model and share tagclouds between social tagging websites

• scot:Tagcloud sioc:taggingActivity tags:Tagging• scot:Tag scot:cooccurs_in scot:Cooccurence

• But… how to represent the meaning of tags ?• “I’m using the tag ‘apple’ in this bookmark and I mean the company”

• This is the goal of MOAT

MOAT: From Tagging to Semantic Web - WWW2008, Dev Track, 2008-04-25, Beijing8

MOAT - Meaning Of A Tag

• MOAT - http://moat-project.org• MOAT aims to provide

• An ontology to represent global and local meaning of tags in a machine-understandable way, using URIs of Semantic Web resources to define those meanings

• A framework to assign and share meanings to tags in a collaborative and open way

• A way to let tags embeds themselves their semantic• A process to create Linked Data from simple tagging actions and offer to

ways to discover related content and people

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Tags and their meanings

• Tagging action is usually defined as a tripartite model• Tagging(User, Resource, Tag)

• MOAT extends the model with the local meaning of a tag• Tagging(User, Resource, Tag, Meaning)• “In this tagging action ‘paris’ refers to the french city”

• Yet, a tag can have different global meanings in a complete folksonomy space

• Involves a social aspect• Meanings(Tag) = {(Meaning, {User})}

• Meanings(‘apple’) = {(the apple fruit, {me, bob, julie}), (apple inc., {me})}

MOAT: From Tagging to Semantic Web - WWW2008, Dev Track, 2008-04-25, Beijing10

Defining machine-understandable meanings for tags

•Using URIs of existing resources from the Semantic Web• Linking Open Data provides references datasets and URIs

• http://dbpedia.org/resource/Apple• http://dbpedia.org/resource/Apple_Inc.

http://richard.cyganiak.de/2007/10/lod/

MOAT: From Tagging to Semantic Web - WWW2008, Dev Track, 2008-04-25, Beijing11

Linking tags to their meanings

• The MOAT Ontology - http://moat-project.org/ns• Modeling tags

• Tag class, extending the Tag Ontology• Mappings with SCOT in progress• Cardinality restriction regarding the name property (=1)

• Modeling global meanings of a tag• TagMeaning class and meaningURI property• Relies on FOAF for the user aspect - cardinality>=1• hasMeaning property to link it to the Tag

• Modeling local meaning of a tag• Using the RestrictedTagging class from the Tag Ontology• tagMeaning property to define the local meaning of a tag• Cardinality restriction (=1)

MOAT: From Tagging to Semantic Web - WWW2008, Dev Track, 2008-04-25, Beijing12

MOAT ontology diagram

MOAT: From Tagging to Semantic Web - WWW2008, Dev Track, 2008-04-25, Beijing

MOAT data example

<http://tags.moat-project.org/tag/apple> a moat:Tag ;

moat:name "apple" ; moat:hasMeaning [ a moat:Meaning ;

moat:meaningURI dbpedia:Apple ; foaf:maker <http://example.org/alex/>

] ; moat:hasMeaning [ a moat:Meaning ;

moat:meaningURI dbpedia:Apple_Inc. ; foaf:maker <http://myblog.net/user.rdf#me> ;

foaf:maker <http://example.org/alex/> ] .

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Tagging action using MOAT

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The MOAT framework

• Goal: provide an easy way to create local and global meanings for tags• A client-server approach

• People subscribe to a MOAT server and install a client on their tagging software

• When people create tagged content, client queries the server for tags meaning(s) and lets user define with new ones if needed

• People link their tagged content to the meaningful URI• A collaborative and decentralized approach

• Anyone can benefit from user-defined meanings in a community• Needs only a few active users to be deployed• Clients can be anywhere on the web, on any platform• Could use social networking aspects to suggest URIs

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The MOAT framework architecture

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MOAT architecture principles

• RESTful way to exchange between a server and clients• Data exchanged between both is modeled in RDF• Each tag URI on the MOAT server is dereferencable• Uses content-negociation

• http://tags.moat-project.org/tag/rdf• Provides direct access to RDF output and to JSON

• Developers do not need to learn RDF• http://tags.moat-project.org/tag/rdf/json• http://tags.moat-project.org/tag/rdf/json/light

• Update tag meanings by sending an RDF file with some TagMeaning instances (automatically created with a MOAT client) to the server

• Optional API key to restrict updates to some members• http://tags.moat-project.org/?update=

MOAT: From Tagging to Semantic Web - WWW2008, Dev Track, 2008-04-25, Beijing18

Current implementations

• MOAT Server • Current implementation as a PHP5 application• Can be plugged-in on any triple-store (ARC2, 3store bindings)• Using SPARQL / SPARUL to manage data• Open-source• http://moat-project.org/server

• MOAT Clients• Drupal client, features Sindice interaction

• Helps users to find new URI if needed• OpenLink Data Spaces• http://moat-project.org/clients• Write your own ! PHP API coming soon

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MOAT, Drupal and Sindice

MOAT: From Tagging to Semantic Web - WWW2008, Dev Track, 2008-04-25, Beijing

Drupal RDF output example

• Post - Using SIOC and related vocabularies•Tagging actions - Using the Tag Ontology and MOAT

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New ways to interlink RDF data

• By linking tagged content to URIs, it provides new way to connect those contents

• Create content and tag it• Use MOAT to link it to some URI

of the LOD datasets• Use relationships between

those URIs to discover new content

• Helps SIOC entering the Linked Data Web

• Since sioc provides a way to represent tagged content

• sioc:Item and its subclasses• sioc:topic property

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Summary

• MOAT is about• Offering an RDF model to define the meaning(s) of tags• Letting tagged content enters the Semantic / Linked Data Web• Offering an open-source framework to collaboratively achieve this goal

• MOAT is not about• Automatic identification of URI from tag• Automatic way to remove tag ambiguity• Ontology mining from tags• … but aims to provide an RDF model for such algorithms

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Thank you ! / Questions

http://moat-project.orghttp://apassant.net