Ozone Browser: Augmenting the Web with Semantic
                       Overlays

                 Grégoire Burel1, Amparo E. Cano1 and Vitaveska Lanfranchi1
            1
                OAK Group, Department of Computer Science, University of Sheffield,
                                  Sheffield, United Kingdom
                       {G.Burel, A.Cano,V.Lanfranchi}@dcs.shef.ac.uk


   This paper presents Ozone Browser1 (OB), a JavaScript tool that uses the semantics
embedded in Web documents for improving the user interaction experience.
   Recently, the introduction of Microformats2 and then RDFa3 created a bridge
between the Semantic Web and the Syntactic Web by embedding semantics into Web
documents. This bridge facilitates the consumption of semantic data by third party
applications such as screen scrappers, or search engines. However, until now the
human-readable presentation of these semantic meta-information has been set aside.
From the reader’s point of view, the actual interpretation of a rendered document
relies on: 1) The contextual knowledge provided by the hyperlinks contained in a
document; 2) The background knowledge of the reader that helps him to bind
unlinked information to known concepts. However, when following hyperlinks the
reader may be disturbed on its cognitive process as it loses the information given by
the previous document. Moreover, the association process with the user knowledge
rather than the publisher knowledge may conduct to misinterpretation or partial
understanding of the document. As computers, a reader should use the document’s
internal and external semantics for leading him to a better understanding of it. For
making it possible, it is required to augment the document's representation by making
explicit this underlying and external knowledge in a human readable way. OB is a
graphical overlay that uses RDFa enabled documents for fulfilling these requirements.
It uses a progressive enhancement strategy based on RDFa markups for adding
different presentation layers to an existing document.
   First, OB extracts the semantic content from a document by creating a lightweight
client-side triple store from which inferences from the document's RDFa statements
can be derived. Then, it binds a graphical overlay on the top of the current web
document, highlighting all the RDFa statements containing the property tag in the
document via icons. The reader can request more information about these statements
by pointing on them. When doing so, inferences from inside and outside the page are
executed for that statement, a contextualized view of the obtained knowledge is
presented and the related information within the document (statements with the same
predicate) is visualised as lines superimposed on the document itself. In order to
provide these visualisations, OB dynamically generates views accordingly to the
name space of the RDFa statement using a plug-in approach (Fig. 1).

1
  Sparks Ozone Browser, http://www.dcs.shef.ac.uk/~gregoire/sparks/
2
  Microformats, http://microformats.org/
3
  RDFa, http://www.w3.org/TR/xhtml-rdfa-primer/
Fig. 1. Ozone Browser in action: a) the summary of an event; b) the related developer’s view.

   Currently two experimental views are implemented. The first one provides a view
of a Twitter4 account (last Tweets of the considered account and the last public
Tweets). The second one, an Event Visualiser, displays a summary of geotagged
events using a map interface. This summary is generated from the inferences derived
from the statements contained in the triple store. When no suitable views are
available, a default visualisation is provided. It displays the RDFa triple object
alongside with the possibility of finding the related information using search engines.
OB also provides a developer view targeting people aware of Semantic Web
technologies. This view shows the triples of the document in a raw format and offers
an experimental interface for performing simple SPARQL5 queries on the triple store.
   OB is implemented as a bookmarklet6 and can be applied to any web document
with RDFa embedded metadata. It is built on top of two toolkits and uses a JSONP7
bridge from Yahoo Pipes8. It uses the rdfquery library9, which is a lightweight client-
side toolkit for RDFa, and the Sparks framework1, both implemented in JavaScript.
   OB has been designed within the WeKnowIt10 project as a solution for interacting
implicitly with knowledge outside and inside the document boundaries, while
preserving the knowledge context. Future work includes: 1) Refining the context-
based views and introducing more sophisticated visualisation plug-ins; 2) Providing
means to manipulate the knowledge objects in the page, thus offering easy ways to
enrich a document with the user knowledge.

Acknowledgements
  The research leading to these results has received funding from the EU project
WeKnowIt10 (ICT-215453).

4
  Twitter, http://twitter.com/
5
  SPARQL, http://www.w3.org/TR/rdf-sparql-query/
6
  A bookmarklet consists of a snippet of JavaScript code that can be dragged/dropped into the
   browser's tool bar and can be applied to any web page in order to process a Web document.
7
  JSONP, http://bob.pythonmac.org/archives/2005/12/05/remote-json-jsonp/
8
  Yahoo Pipes, http://pipes.yahoo.com/pipes/
9
  Rdfquery Library, http://code.google.com/p/rdfquery/
10
   WeKnowIt, http://www.weknowit.eu/