Ad-hoc light weight SPARQL endpoint from a file, using Python Flask and RDFLib

Sometimes one needs to set up a quick SPARQL endpoint for a local Turtle file without installing a triplestore. This is a quick demo how to use the Python 3 microframework Flask and RDFLib to provide an Ad-Hoc SPARQL endpoint based on a Turtle or RDF/XML file.

Example:

./adhs.py file.ttl -i turtle -p 5000

The -i parameter is optional but should be used to specify the format of the file. If it's missing, rdflib.util.guess_format() will be used.

The -p parameter is optional as well. If not provided, flask will be accessible on default port 5000. Navigate to

http://localhost:5000/sparql

to get a very basic form to enter and submit your queries (the form is just some icing on the cake).

Additionally, the SPARQL endpoint accepts GET requests:

http://localhost:5000/sparql?query=select distinct ?s where { ?s a ?c }

The answer format will always be JSON, there is no content negotiation at the moment but will probably be implemented in the future.

One use case behind the adhs was to provide a quick possibility to set up different ontologies to test them with the Visual SPARQL Builder (VSB) without having to load them into a triplestore like Virtuoso. Additionally, since the VSB needs SPARQL 1.1, it is a convenient alternative on systems don't have high enough version of Virtuoso installed.

ADHS is actually the German abbreviation for ADHD.

moved to TODO.md