David S. Read

I had the pleasure of attending the Semantic Technology and Business Conference in Washington, DC last week.  I have a strong interest in semantic technology and its capabilities to enhance the way in which we leverage information systems.  There was a good selection of topics discussed by people with a variety of  backgrounds working in different verticals.

To begin the conference I attended the half day “Ontology 101” presented by Elisa Kendall and Deborah McGuinness.  They indicated that this presentation has been given at each semantic technology conference and the interest is still strong.  The implication being that new people continue to want to understand this art.

Their material was very useful and if you are someone looking to get a grounding in ontologies (what are they?  how do you go about creating them?) I recommend attending this session the next time it is offered.  Both leaders clearly have deep experience and expertise in this field.  Also, the discussion was not tied to a technology (e.g. RDF) so it was applicable regardless of underlying implementation details.

I wrapped up the first day with Richard Ordowich who discussed the process of reverse engineering semantics (meaning) from legacy data.  The goal of such projects being to achieve a data harmonization of information across the enterprise.

A point he stressed was that a business really needs to be ready to start such a journey.  This type of work is very hard and very time consuming.  It requires an enterprise wide discipline.  He suggests that before working with a company on such an initiative one should ask for examples of prior enterprise program success (e.g. something like BPM, SDLC).

Fundamentally, a project that seeks to harmonize the meaning of data across an enterprise requires organization readiness to go beyond project execution.  The enterprise must put effective governance in place to operate and maintain the resulting ontologies, taxonomies and metadata.

The full conference kicked off the following day.  One aspect that jumped out for me was that a lot of the presentations dealt with government-related projects.  This could have been a side-effect of the conference being held in Washington, DC but I think it is more indicative that spending in this technology is more heavily weighted to public rather than private industry.

Being government-centric I found any claims of “value” suspect.  A project can be valuable, or show value, without being cost effective.  Commercial businesses have gone bankrupt even though they delivered value to their customers.  More exposure of positive-ROI commercial projects will be important to help accelerate the adoption of these technologies.

Other than the financial aspect, the presentations were incredibly valuable in terms of presenting lessons learned, best practices and in-depth tool discussions.  I’ll highlight a few of the sessions and key thoughts that I believe will assist as we continue to apply semantic technology to business system challenges.

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I was recently asked about the SPARQL support in Sparql Droid and whether it could serve as a way for other Android applications to execute SPARQL queries against remote data sources.  It could be used in this way but there is a simpler alternative I’d like to discuss here.

On the Android platform it is actually quite easy to execute SPARQL against remote SPARQL endpoints, RDF data and local models.  The heavy lifting is handled by Androjena’s ARQoid, an Android-centric port of HP’s Jena ARQ engine.

Both engines (the original and the port) do a great job of simplifying the execution of SPARQL queries and consumption of the resulting data.  In this post I’ll go through a simple example of using ARQoid.  Note that all the code being shown here is available for download.  This post is based specifically on the queryRemoteSparqlEndpoint() method in the com.monead.androjena.demo.arqoid.SparqlExamples class.

Setup

To begin, some environment setup needs to be done in order to have a properly configured Android project ready to use ARQoid.

First, obtain the ARQoid JAR and its dependencies.  This is easily accomplished using the download page on the ARQoid Wiki and obtaining the latest ARQoid ZIP file.  Unzip the downloaded archive.   Since I’m discussing an Android application I’d expect that you would have created an Android project and that it contains a libs directory where the JAR files should be placed.

Second, add the JAR files to the classpath for your Android project.  I use the ADT plugin for Eclipse to do Android development.  So to add the JARs to my project I choose the Project menu item, select Properties, choose Build Path, select the Libraries tab, click the Add JARs… button, navigate to the libs directory, select the JAR files and click OK on the open dialogs.

Third, setup a minimal Android project.  The default layout, with a small change to its definition will work fine.

Overview

Now we are ready to write the code that uses ARQoid to access some data.  For this first blog entry I’ll focus on a trivial query against a SPARQL endpoint.  There would be some small differences if we wanted to query a local model or a remote data set.  Those will be covered in follow-on entries.

Here is a list of the ARQoid classes we will be using for this initial example:

• com.hp.hpl.jena.query.Query – represents the query being executed
• com.hp.hpl.jena.query.Syntax – represents the query syntaxes supported by ARQoid
• com.hp.hpl.jena.query.QueryFactory – creates a Query instance based on supplied parameters such as the query string and syntax definition
• com.hp.hpl.jena.query.QueryExecution – provides the service to  execute the query
• com.hp.hpl.jena.query.QueryExecutionFactory – creates a QueryExecution instance based on supplied parameters such as a Query instance and SPARQL endpoint URI
• com.hp.hpl.jena.query.ResultSet – represents the returned data and metadata associated with the executed query
• com.hp.hpl.jena.query.QuerySolution – represents one row of data within the ResultSet.

We’ll use these classes to execute a simple SPARQL query that retrieves some data associated with space exploration.  Talis provides an endpoint that we can use to access some interesting space exploration data.  The endpoint is located at http://api.talis.com/stores/space/services/sparql.
The query we will execute is:

SELECT ?dataType ?data
WHERE {
  <http://nasa.dataincubator.org/launch/1961-012> ?dataType ?data.
}

This query will give us a little information about Vostok 1 launched by the USSR in 1961.

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