Have you ever been taught how to knit? I you have, then you'll know that you are not usually taught how to cast on (or start off) on your first lesson. That's because it much easier to learn how to knit than it is to cast on.
So it is with the Semantic Web. Once you have a resource URL, it's reasonably easy to extract information linked to that resource, but finding the starting resource is a bit trickier.
So let's just recap how we might get the abstract description for London from DBpedia.
If we know the URL then that's pretty straight forward:
(If you want to follow this tutorial, then you had better copy the sparql.py file from there.)
|RDF types for the DBpedia entry for London|
Just to be a smart ass as I finish off, you can get both at the same time by doing this, but don't forget that doing this will stress the SPARQL endpoint more than is probably necessary. Be kind.