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Archive for November, 2010

Creating a SPARQL Endpoint Using Joseki

Monday, November 29th, 2010

Being a consumer of semantic data I thought creating a SPARQL endpoint would be an interesting exercise.  It would require having some data to publish as well as working with a SPARQL library.  For data, I chose a set of mileage information that I have been collecting on my cars for the last 5 years.  For technology, I decided to use the Joseki SPARQL Server, since I was already using Jena.

For those who want to skip the “how” and see the result, the SPARQL endpoint along with sample queries and a link to the ontology and data is at: http://monead.com/semantic/query.html

The first step in this project was to convert my mileage spreadsheets into triples.  I looked briefly for an existing ontology in the automobile domain but didn’t find anything I could use.  I created an ontology that would reflect my approach to recording automobile mileage data.  My data  records the miles traveled between fill-ups as well as the number of gallons used.  I also record the car’s claimed MPG as well as calculating the actual MPG.

The ontology reflects this perspective of calculating the MPG at each fill-up.  This means that the purchase of gas is abstracted to a class with information such as miles traveled, gallons used and date of purchase as attributes.  I abstracted the gas station and location as classes, assuming that over time I might be able to flesh these out (in the spreadsheet I record the name of the station and the town/state).

A trivial Java program converts my spreadsheet (CSV) data into triples matching the ontology.  I then run the ontology and data through Pellet to derive any additional triples from the ontology.  The entire ontology and current data are available at http://monead.com/semantic/data/HybridMileageOntologyAll.Inferenced.xml.

It turns out that the ontology creation and data conversion were the easy parts of this project.  Getting Joseki to work as desired took some time, mostly because I couldn’t find much documentation for deploying it as a servlet rather than using its standalone server feature.  I eventually downloaded the Joseki source in order to understand what was going wrong.  The principle issue is that Joseki doesn’t seem to understand the WAR environment and relative paths (e.g. relative to its own WAR).

I had two major PATH issues: 1) getting Joseki to find its configuration (joseki-config.ttl); and 2) getting Joseki to find the triple store (in this case a flat file).


Semantic Web Summit (East) 2010 Concludes

Thursday, November 18th, 2010

I attended my first semantic web conference this week, the Semantic Web Summit (East) held in Boston.  The focus of the event was how businesses can leverage semantic technologies.  I was interested in what people were actually doing with the technology.  The one and a half days of presentations were informative and diverse.

Our host was Mills Davis, a name that I have encountered frequently during my exploration of the semantic web.  He did a great job of keeping the sessions running on time as well as engaging the audience.  The presentations were generally crisp and clear.  In some cases the speaker presented a product that utilizes semantic concepts, describing its role in the value chain.  In other cases we heard about challenges solved with semantic technologies.

My major takeaways were: 1) semantic technologies work and are being applied to a broad spectrum of problems and 2) the potential business applications of these technologies are vast and ripe for creative minds to explore.  This all bodes well for people delving into semantic technologies since there is an infrastructure of tools and techniques available upon which to build while permitting broad opportunities to benefit from leveraging them.

As a CTO with 20+ years focused on business environments, including application development, enterprise application integration, data warehousing, and business intelligence I identified most closely with the sessions geared around intra-business and B2B uses of semantic technology.  There were other sessions looking a B2C which were well done but not applicable to the world in which I find myself currently working.

Talks by Dennis Wisnosky and Mike Dunn were particularly focused on the business value that can be achieved through the use of semantic technologies.  Further, they helped to define basic best practices that they apply to such projects.  Dennis in particular gave specific information around his processes and architecture while talking about the enormous value that his team achieved.

Heartening to me was the fact that these best practices, processes and architectures are not significantly different than those used with other enterprise system endeavors.  So we don’t need to retool all our understanding of good project management practices and infrastructure design, we just need to internalize where semantic technology best fits into the technology stack.