Say hello to lodr.info

In one of my recent post, I mentionned LODr, a semantic-tagging application based on MOAT. While I started it a few months ago, it’s finally online now. I put the code in svn last friday and twitted about it, but did not make any official announcement yet, so here it is. I certainly should have released before, but as the source code involves lots of classes, I wanted to be sure of the architecture.

So, what is it about ?

LODr aims to apply to MOAT principles (in a few words, link your tags to concepts URIs - people URI, Musicbrainz artists, DBpedia resources … - , share those relationships in a community and then tag content with those URIs) to existing Web 2.0 content. So you can “re-tag” your existing Flickr pics, slideshare presentations, etc, using those principles and make your social data enter the LOD cloud. I think focusing on the existing word is important here, as LODr lets you keep your Web 2.0 habits by using your favourite tools, but provides a separate service to semantically-enrich it. I don’t want to go into too much details here, but in brief, some interesting points regarding the applications are:

• While tags / URIs relationships are shared within the LODr community in a central RDF-base (following the MOAT architecture principles), LODr is a personal application, so that you just need to install the software on your webserver to enjoy it. Moreover, as it’s local, you can re-use your data immediately for any mash-up;
• LODr is completely RDF-based. It might be a bit geeky, but as some were recently wondering where are all the RDF-based applications, here’s one. And of course RDF-based means using standard vocabularies, such as SIOC, FOAF, DC, the Tag Ontology and of course MOAT. The RDF-backend is powered by ARC2, so you can enjoy a SPARQL endpoint for your data. Last but not least, each item page features RDFa, using the previous vocabularies, even if you decide not to use MOAT for a particular item (so that any Web 2.0 item you aggregate is RDFa-ized);
• Aggregated data will provide you a complete tagcloud for your social activity (which might be SCOT-ed in the next updates), as seen here. Each tag link redirects to a list of items provided using Exhibit, and you can restrict by source (i.e. the service it’s from) or creation date. And if a tag have been assigned a URI, you’ll get a link to browse the related items using a similar interface;
• When browsing all items tagged with a particular URI, you’ll get suggested some related URIs. Related because of co-occurence as usually in tag-based applications, but also because they’re directly interlinked, or because they share a common property. To avoid information overload, only the URIs you used to re-tag some of your items will be shown;
• The application can be easily extended. LODr uses wrappers to retrieve your data, and each wrapper is only a few lines of code (e.g. 24 lines for the Flickr one). At the moment, wrappers use RSS to retrieve data and the feeds are automatically discovered from the user FOAF profile - dataportability rocks ! Yet, the architecture allows to use authenticated wrappers (to use services API) but also SIOC exports for those tools;
• As the MOAT process is more time-consuming that simple tagging (since you must define tag/URI relationships, at least at the first time as you can do automated tagging after) the URIs can be displayed as labels when you need to choose which one is relevant for your tag (using the inference capabilities described here as not all resources have a direct rdfs:label property ) . When you need a new URI, the application relies on the Sindice search widget, as done in the Drupal MOAT module. And the system then checks if the new URI is valid, but I’ll blog about that particular point later;
• Finally, in addition of the previous features, LODr can be used to discover all the community content. This feature is not provided by the local application, but by LODr.info, that aggregates your RDF data when you re-tag it to provide search capabilities. Then, you can directly list all items linked to a particular URI. Want to find content related to the Forbidden City ? Or to SPARQL ? And to be even more enjoyable, I added a Ubiquity command so that from any Wikipedia page (more services will be supported soon), you can get the list of all related items (through DBpedia in order to find the concept URI from a document page). While it provides a really-straightforward way to discover related Web 2.0 content when browsing the Web, I also hope it can convice people of the complete process.

So, you can simply download the code from the website and install it. For those who just want to have a look, you can check my LODr instance (while you won’t be able to edit it, you can check the display interfaces). As there might be some bugs and I’m still adding features, please consider using the SVN version instead of the tgz. And then, enjoy the power of Linked Data for your Web 2.0 content

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• About

  This is the personal website of Alexandre Passant, PhD student in the Semantic Web and Social Software area.

• Websites

  • doap:store
  • FOAFMap
  • MOAT Project

• Current highlights

  

• Recent Posts

  • SDoW2008 tagcloud
  • SDoW2008: Program and proceedings
  • SIOC goes OWL-DL
  • Were are all the Semantic Web presentations ?
  • Say hello to lodr.info