sesame-playground

This is my first attempt to use Sesame, a Java-based semantic web toolkit from Clojure. You'll find simple Leiningen project along with three sample queries (see resources/queries) against 3 ontologies:

GoodRelations: an established vocabulary for e-commerce with wide industry support
an early development snapshot two other ontologies for the domain of printers and perfumes developed for the OPDM project

The project contains a few useful functions that will help you create an in-memory triple store (a kind of database if you will), load arbitrary RDF/XML data into the triple store and run SPARQL queries against the data.

Requirements

I assume you have at least JDK 1.6 installed on your machine.

Before you start, make sure you have Leiningen installed. If not, simply download this script, place it on your $PATH and run

lein self-install

Download and unzip the source into an empty folder or simply clone the repository:

git clone https://github.com/laczoka/sesame-playground.git
cd sesame-playground
lein deps

Usage

Run the tests

This is not very informative, but it leverages the standard test framework of clojure.

lein test

Check out the code under in the test directory.

Experiment with a triple store form the REPL

The REPL (Read-Eval-Print-Loop) is an interactive environment that you can use to experiment with Sesame and the code in this project.

For a start, go to the project's directory and run

lein repl

You are now in an interactive programming environment that resembles a shell. Let's import the central namespace so we can start working:

(use 'sesame-playground.core)

Let's create a triple store:

(def ts (create-triple-store))

Now that we have a triple store let's insert some triples into it using the n-triples syntax:

(insert-triples ts ["<http://name.me/Laszlo> <http://xmlns.com/foaf/0.1/name> \"Laszlo\"."])

You can also load RDF/XML (e.g. the GoodRelations ontology) files and insert them into the triple store:

(insert-triples ts (java.io.File. "resources/ontologies/gr.owl"))

So now we have some data in our triple store, let's issue a few queries. Let's get all foaf:name values in our store:

(query-result-set ts (with-common-ns-prefixes "SELECT ?name WHERE { ?s foaf:name ?name.}"))

and we get

#{{:name "\"Laszlo\""}}

#{ .. } denotes a set, the result set returned by the query. {:name ""Laszlo""} is a map (or dictionary), where :name corresponds to ?name in the SPARQL query and "Laszlo" is the string literal.

Note: the with-common-ns-prefixes simply prepends the SPARQL query with the most common namespace prefixes to save you some typing effort.

You can clear a store by calling:

(clear-store ts)

Test this by issuing:

(.isEmpty (.getConnection ts))

should return

true

At this point you now how to create a triple store, how to add triples to it and how to query the triple store. Check out the code for technical details!

License

Provided as is!