The application showcases the ideas of a distributed, SemanticWeb enabled microblogging architecture, providing a way to leverage this new Web 2.0 practice to the Semantic Web. Microblogging is one of the recent social phenomena of Web 2.0 but unlike blogs or wikis has not yet been leveraged to the Semantic Web. To achieve this goal, we designed a semantically-enabled distributed architecture for semantic microblogging, which relies on an open world of publishing clients and aggregation servers that exchange data modelled in RDF. When users write microblog posts within their clients, RDF les are created on the client webservers, describing the posts using FOAF [3] and SIOC [2], and pushed live to a number of aggregation servers. Thus, the user really owns his data and can reuse it locally for other purposes, either browsing or merging with other RDF data, while aggregation servers are mainly dedicated to providing a browsing interface for shared communities. To model updates, we extended the SIOC types module [1] with a MicroblogPost class, as well as Microblog to model the service itself. Thanks to the use of existing libraries, the code of both the client and the server is really light1. The client uses the SIOC PHP API2 to create the RDF les from an HTML form submission, and is only 57 lines of code. This le is pushed to some aggregation servers (chosed from the list of servers stored in the client con guration le) using CURL. Regarding the server, we rely on ARC23 which provides a lightweight environment for developing RDF-based applications in PHP. The server uses the SPARUL LOAD instruction to store received updates in the server backend store, and a single SPARQL query to render a view of public updates. To make the interface fancier, we use Exhibit [4] to display a faceted view of these latest updates. These facets include date and author but also some user-de ned data. Indeed, the server features a preprocessor 1 http://code.google.com/p/smob/ 2 http://wiki.sioc-project.org/index.php/PHPExportAPI 3 http://arc.semsol.org
Alexandre Passant, Tuukka Hastrup, Uldis Bojars, John Breslin that allows users to use some semantic hashtags in their updates. The current implementation includes a GeoNames4 mapping, allowing users to use tags like #geo:paris france to retrieve the URI of the related resource, thus providing a way to leverage location-based microblogging to the Linked Data Web. Consequently, this mapping permits the use of the geographical rendering part of Exhibit, as shown on Fig. 1 Other simple topics can be extracted with a similar processor and can also be linked to DBPedia with a given pre x.
This material is based upon work supported by Science Foundation Ireland under grant number SFI/02/CE1/I131. 4 http://geonames.org