My presentation on RDFauthor at EKAW2010, Lisbon. For more information on RDFauthor visit http://aksw.org/Projects/RDFauthor; for the code visit http://code.google.com/p/rdfauthor/.

1. Employing RDFa for Collaborative
Knowledge Engineering
Sebastian Tramp, Norman Heino,
Sören Auer, Philipp Frischmuth
Agile Knowledge Engineering and Semantic Web (AKSW) – Universität Leipzig

2. Knowledge Engineering
on the Web
• HTML forms are
unaware of semantics
• HTML5 allows pre-
defined input state
semantics
• Sophisticated user
support requires
definable semantics!
Currently: hard-wired semantics, abuse of class attributes

3. RDFa
• Annotating XML
documents with RDF
• Human and machine-
readable
• MVC – declare view in
model language
Images: http://www.w3.org/TR/xhtml-rdfa-primer/

4. Knowledge Engineering
by Employing RDFa
• RDFa page, updatable
knowledge store HTTP
Web XHTML
• + Edit
"Intelligent" editing Server
+
RDF Store
RDFa
components (widgets)
SPARQL/Update
• Supporting the user

5. Requirements
for RDFauthor
• Editing data chunks
• Standards-based
update
• Light-weight addition
• Extensible widget pool
• Multiple sources

6. Named Graphs and Provenance
Extending RDFa
• Data source for each
triple
• Update endpoint
(SPARQL/Update)
• Query endpoint for
reference (SPARQL)

7. RDFa Example
<p about="http://sebastian.tramp.name" typeof="foaf:Person">
<img rel="foaf:depiction" src="http://aksw.org/img/…" />
<strong property="foaf:name">Sebastian Tramp</strong>
</p>

8. RDFa Example
from Two Sources
<p about="http://sebastian.tramp.name" typeof="foaf:Person">
<img rel="foaf:depiction" src="http://aksw.org/img/…" />
<strong property="foaf:name">Sebastian Tramp</strong>
</p>
<p about="http://www2009.eprints.org/63/1/p621.pdf"
typeof="foaf:Document">
<span property="dc:description">…</span>
Author: <span rel="foaf:maker"
resource="http://sebastian.tramp.name">…</span>
</p>

9. RDFa Example
with Named Graphs
<div update:from="http://showcase.ontowiki.net/">
<p about="http://sebastian.tramp.name" typeof="foaf:Person">
<img rel="foaf:depiction" src="http://aksw.org/img/…" />
<strong property="foaf:name">Sebastian Tramp</strong>
</p>
</div>
<div update:from="http://publications.aksw.org">
<p about="http://www2009.eprints.org/63/1/p621.pdf"
typeof="foaf:Document">
<span property="dc:description">…</span>
Author: <span rel="foaf:maker"
resource="http://sebastian.tramp.name">…</span>
</p>
</div>
http://buzzword.org.uk/2009/rdfa4/spec

10. Provenance
<link about="http://showcase.ontowiki.net/"
rel="update:updateEndpoint"
href="http://trunk.ontowiki.net/sparql/" />
<link about="http://showcase.ontowiki.net/"
rel="update:updateEndpoint"
href="http://trunk.ontowiki.net/sparql/" />
@prefix update: <http://ns.aksw.org/update/> .

11. Implementation
• Page creation
Extracted Triples
• Client-side page
processing XHTML
+
RDFa
• Widget selection/form
HTML Form
creation
RDF Store
• Update propagation

12. System Architecture
RDFauthor3
W3C RDFa
rdfQuery1
parser2 (+NG)
1http://code.google.com/p/rdfquery/
2http://www.w3.org/2006/07/SWD/RDFa/impl/js/
3http://code.google.com/p/rdfauthor/

13. Widgets
• Semantics-aware
• Hide confusing options
by default
• One widget edits one
statement's object
• Register for widget
hooks

14. Widget Hooks
Hook name Hook value (example)
subject URI http://id.feedface.de/me
rdfs:range of predicate rdfs:Literal
rdfs:Datatype of object xsd:string
predicate URI http://xmlns.com/foaf/0.1/name
rdf:type of object rdfs:Literal

15. Widgets (contd.)
xsd:date
rdf:Resource

16. Overlay Form
• Structure-agnostic
• Widgets can be
grouped by predicate
• Decelerated workflow

17. Inline Form
• Seamless integration
• Form layout follows
markup structure
• Structure-aware
• Problems with certain
RDFa features

18. Update Propagation
• Widgets update graphs
• Calculate diff graphs
RDF Store
• Sent via SPARQL/Update
to each source

19. Use Cases
and Evaluation

20. OntoWiki

21. Wiki Pages

22. Wiki Pages (contd.)

23. Data Collection

24. Data Collection (contd.)

25. Conclusions
• RDFauthor allows to create editable
semantic mashups
• Shields the user from RDF model
intricacies
• Minimal impact on the web page being
edited

26. Demo Session
Wednesday, 4 – 6pm, Room 2
… or anytime