Produce and Consume Linked Data with Drupal!

Transcription

1 Produce and Consume Linked Data with Drupal! Stéphane Corlosquet, Renaud Delbru, Tim Clark, Axel Polleres and Stefan Decker ISWC 2009 DERI NUI Galway, MGH October 27th, 2009 Copyright All rights reserved. Chapter 1

2 Loads of Data on the Web in CMS... 2

3 Some Motivations... Status of the current web Data contained in millions of documents Disparate platforms and systems Wide range of topics (personal blogs, news, etc.) Various types of resources (text, pictures, video, etc.) Note: Lots of Structured data in Content Management Systems Problem Not possible to reuse this data outside the CMS (except RSS) Not available as unified machine readable format 3

4 So, here s our idea of CMS: PROJECT BLOGS DBLP SPARQL endpoint REMOTE DRUPAL SITE SPARQL endpoint Tim... SELECT?name?title WHERE {?person foaf:made?pub.?person rdfs:label?name.?pub dc:title?title. FILTER regex(?title, "knowledge", "i") } SPARQL endpoint Figure 3.5: Extended example in a typical Linked Data eco-system. 4

5 Approach Our Goal Integrate "any" CMS site to the Web of Data A challenging task Little incentive for users to annotate their data manually Site owners do not have the resources to convert their data to RDF Per-site schema: each site is different and its structure cannot be predefined Solutions Expose the CMS site structure in a unified format AUTOMATICALLY! Use Semantic Web standards (RDFa, SPARQL) 5

6 Approach Implementation in Drupal Why? One of the most popular CMS out there Modules to take the burden off the site users What our modules allow: 1. Automatic site vocabulary generation 2. Mapping Content Models to existing ontologies 3. Data endpoint for SPARQL querying 4. Lazy loading of external data (data import) 6

7 Pre-Existing work Semantic Content Management Systems Ontology-based CMS: Semantic community Web portals (2000) OntoWebber: Model-Driven Ontology-Based Web Site Management (2001) Our approach is reverse: from existing CMS structure to ontologies 7

8 The Drupal CMS Drupal* Easy to use Large community Popular on the Web Hundreds of thousands of sites Modular design Drupal site workflow Site administrator: set up the site and install modules they like/need Site editors: create the content of the site following the schema defined by the site administrator * 8

9 Drupal: Content Construction Kit Content Construction Kit (CCK) module GUI for extending the internal schema of a Drupal site Used on many Drupal sites Can build new types of pages, known as content types Can create fields for each content types. Fields can be of various types: plain text fields, dates, addresses, file uploads, reference to other pages 9

10 Drupal: Content Construction Kit Demo use case: project blogs site* Community Various site content: People Organizations Projects Blogs PROJECT BLOGS DBLP SPARQL endpoint SPARQL endpoint SELECT?name?title WHERE {?person foaf:made?pub.?person rdfs:label?name.?pub dc:title?title. FILTER regex(?title, "knowledge", "i") } REMOTE DRUPAL SITE Tim... SPARQL endpoint Figure 3.5: Extended example in a typical Linked Data eco-system. * one for bridging the DBLP SPARQL endpoint to the project blogs website, and a second for bridging the Science Collaboration Framework website. When visiting Tim s profile page, the relevant publication information will be fetched from both DBLP and SCF websites, and either new nodes will be created on the site or older ones will be updated if necessary Neologism: Easy RDFS vocabulary publishing Neologism11 is a web-based vocabulary editor and publishing platform designed to

11 Drupal: Content Construction Kit CCK User Interface 11

12 Drupal: Content Construction Kit CCK User Interface 12

13 Drupal: Content Construction Kit CCK User Interface 13

14 What do we add? 1, 2 14

15 1. Site Vocabulary Automatic site vocabulary in RDFS/OWL from CCK Describes the content types and fields Content type <=> RDF class Field <=> RDF property RDFa output on site 15

16 1. Site Vocabulary Automatic site vocabulary in RDFS/OWL Field constraints Example with cardinalities: the name of a Person is required max. 5 projects per person 16

17 2. Mapping Content Models to existing ontologies Mapping Content Models to Existing Ontologies Import of any vocabulary published online External ontology search service Local terms are subclasses/subproperties of public terms site:person rdfs:subclassof foaf:person site vocabulary; wherever a mapping is definined, extra trip Ensure safe vocabulary re-use: only subclassing/subproperty avoids redefinition adding cardinalities might introduce inconsistencies still, possible to avoid in the user interface 17

18 2. Mapping Content Models to existing ontologies RDF mappings page 18

19 2. Mapping Content Models to existing ontologies RDF mappings page 19

20 What do we add? 3 1, 2 20

21 3. Data endpoint for complex querying Local RDF data exposed in a SPARQL endpoint Enables interoperability across sites Built on the PHP ARC2 library All RDF data indexed in the endpoint Each page stored as graph and kept up to date 21

22 3. Data endpoint for complex querying Local RDF data exposed in a SPARQL endpoint enable interoperability across sites built on the PHP ARC2 library all RDF data indexed in the endpoint Each page stored as graph and kept up to date 22

23 What do we add? 4 3 1, 2 23

24 4. Lazy loading of external data Lazy loading (caching) of distant RDF resources Enables interoperability across sites Built on the PHP ARC2 library CONSTRUCT query to map distant schema to local schema 24

25 4. Lazy loading of external data Lazy loading of distant RDF resources 25

26 Where is it used? 26

27 Science Collaboration Framework Web application toolkit based on Drupal Enables online scientific collaboration publishing, annotating, sharing and discussing any content articles, papers, reviews, perspectives, interviews, news, biographies profile information on community members Targets biomedecine communities, but generic in essence Networked sites producing Linked Data 27

28 SCF collaborating sites Stembook (Stem Cell articles and reviews) 28

29 SCF collaborating sites Michael J Fox Foundation (Parkinson disease) 29

30 Conclusion 30

31 Conclusion Structure of CMS sites contain valuable schema information Our suggested workflow : site vocabulary from the local structure (RDF CCK) enables out-of-the-box RDF export: expose your Drupal site to the Web of Data without any additional effort from site admin or content editors (RDF CCK) mapping to existing RDF vocabularies improves integration in the LOD cloud (evoc) SPARQL endpoint Lazy loading of RDF resources (RDF Proxy) 31

32 Conclusion Drupal 6 modules available for download Online prototype 32

33 Good news from Drupal 7: RDF mapping feature committed to Drupal 7 core RDFa output by default (blogs, forums, comments, etc.) using FOAF, SIOC, DC, SKOS. Download development snapshot Currently more than * sites on Drupal 6 waiting to make the switch to Drupal 7 waiting to massively increase the amount of RDF data on the Web Discussion * 33