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A Semantic Web, Linked Data application |
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Topos
is a web application that uses Linked Data and other sources of information from
Web services to present a specialized view for a given geographic location.
This view is composed from three user interface components: the location is
shown on a map, news stories about this location are placed in a timeline and
Linked Data collected for this location are presented in a concept graph.
Topos demonstrates the ability to query and connect Linked Data from the Web,
make inferences using the ontologies underlying the data and present the
syndicated information through a specialized browser with a rich user
interface. Technical Overview Topos
is a client / server application. At the client side is a web application
consisting of a Adobe Flex – based user interface component for selecting the
location and the query options, and for presenting the RDF / linked data
results as a graph using the FlexViz
visualization library. Additionally, the Google maps API is used to show
a map for the selected location and the Simile Timeline component is used
to present in a timeline the NYT stories for the selected location.
Topos
client screenshot Usage
is very simple. The user can select a location either from a list of
locations (top left in the screen) or from the pointers in the map (bottom
left) then presses the ‘Get Linked Data’ button. The provided options are i)
to load or not the linked data (dereference owl:sameAs IRIs), ii) to analyze
or not NYT stories using the Open Calais service and iii) to present the
resulting linked data as either an RDF/triples graph or as a Concept graph. Client
– Server communication Communication
between the client and the server is done via HTTP. The Web client is POSTing
XML encoded requests and similarly receives XML encoded responses. No
authorization is required for accessing the server and the XML data are not
encrypted and no session information is used by either the client or the
server. Topos
server The
HTTP server is implemented using SWI
Prolog and Thea Prolog
library for OWL. Thea library is used for parsing initially the Linked Data
ontologies and subsequently for converting the collected RDF triples into OWL
ontology axioms and perform reasoning on the triples based on the underlying
Ontologies. The SWI’s HTTP package library is used to implement a simple but
efficient HTTP server. Prolog DCG is used for parsing the NYT search API
results. The body text of the stories is then fed to the Open Calais service using Thea Open
Calais service wrapper. Using the application,
fairly straightforward, open select location and options, view the timeline
and graphs.
Topos
server functions Topos web application can accessed from here A short paper describing Topos has been
submitted to the Linked Data
triplification challenge 2010. Topos is open source and support is provided on a
"best-effort" basis by its developer. For any questions, comments
and suggestions please contact: |
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