Copia

Like a pheonix from the flames, I've resurrected an old RDF querying interface called Triclops. It used to be coupled with the 4Suite repository's defunct Dashboard (which I've also tried to resurrect as an XForms interface to a live 4Suite repository - there is more to come on that front, thanks to FormFaces) but I've broken it out into it's own stand alone application. It's driven by this stylesheet which makes use of two XSLT extensions (http://metacognition.info/extensions/remote-query.dd#query and http://metacognition.info/extensions/remote-query.dd#graph) both of which are defined here.

I've updated the tabled,triple result page to include ways to navigate graphs by clicking on subjects (which takes you to a subsequent triple result page for that particular subject), predicates (which takes you to another triple result page with statements which use that predicate), and objects (which allows you to jump from graph to graph along rdfs:seeAlso / rdfs:isDefinedBy relationships). Note that it assumes the objects of rdfs:seeAlso and rdfs:isDefined by are live URIs that return an RDF graph (the most common use for these is for FOAF networks and relationships between ontologies).

I've also included buttons for common, 'canned' queries that can be executed on any graph, such as:

• All classes: type(list(rdfs:Class,owl:Class))
• rss:items: type(rss:item)
• Dated Resources: all()|-dc:date->*
• Today's Items: all()|-dc:date->contains(.,".. today's date ..")
• Annotated Resources: all()|-list(rdfs:label,rdfs:comment,dc:title,dc:description,rss:title,rss:description)->*
• Ontologies: type(owl:Ontology)
• People: type(foaf:Person)
• Everything: all()

In addition, I've added some documentation

P.S.: The nodes in the RDF diagrams generated by Triclops (as an alternative to raw triples) are live links. The JPEG diagrams are associated with image maps (generated by graphviz) that allow you to click on the nodes and the SVG diagrams are rendered with links as well (depending on the level of maturity of your SVG viewer - this might or might not be the prefered diagram format). The SVG diagrams have alot potential for things such as styling and the other possibilities that are standard to SVG.

In all, I think it provides a very user-friendly way to quickly traverse, whittle, and circumnavigate the "Semantic Web" - whoops, there is that phrase again :)

4Suite Repository and 4Suite RDF have become sort of bastard children of recent 4Suite development and I've been focusing my efforts lately in moving the latter along - The former (the Repository) only lacks documentation IMHO as Metacognition is run entirely as a 4Suite Repository instance.

Chimezie Ogbuji

I recently merged an old RDF graphing library (within 4Suite) into the 4Suite 4RDF command-line in preperation for the beta release. The library is called Triclops. With this addition, the 4RDF command-line can now render RDF graphs into a representative SVG or Jpeg diagram.

Using Graphviz

Triclops makes use of Graphviz to render .dot graphs (generated from RDF serializations) into various formats. One of the advantages is that Graphviz's neato can be used to apply a spring graph layout algorithm to the final graph. This often results in a more informative layout of the final graph than the default. The downside is the large amount of processing needed by this function.

4RDF Options

Below is a listing of the 4RDF command-line options

The Triclops integration consists of 3 additions:

First, the additional values to the -s / --serialize option:

• svg
• jpeg

Second, the -g / --graphviz option (which is required when either of the above options are used) takes the path to the dot / neato executables. And finally, the -l / --spring option requests that neato is used instead of dot. This results in the spring algorithm being applied to the graph.

FOAF example

To demonstrate, I'm using the Dan Brickley FOAF example (as listed in the specification). In the terminal below, I list the content of the FOAF document, then convert it to a jpeg diagram first and then an SVG diagram right afterwards (using neato to layout the graph). On my machine, the dot and neato executables are located in /usr/bin, so I set the -g option accordingly:

The generated jpg diagram is below while its svg alternative is here.

Another example

Below are jpeg and svg diagrams of the 4Suite Repository Ontology (modeled in OWL):

• 4SuiteRepository.svg (full graph with spring algorithm applied)
• 4SuiteRepository.jpeg (zoomed out to bird's eye view of graph)

My long-term plan is to make Triclops completely configurable so that the generated graphs are tailored to the user's specification for things such as the font used for text, how to format blank nodes, etc. Porting it to use Pydot might go a long way in this regard.

[Chimezie Ogbuji]