Over a year ago, in Querying geospatial data with SPARQL: Part 1, I described my dream of pulling geospatial data down from Open Street Map, loading it into a local triplestore, and then querying it with queries that conformed to the GeoSPARQL standard. At the time, I tried several triplestores and data sources and never quite got there. When I tried it recently with Ontotext’s free version of GraphDB, it all turned out to be quite easy.
I’ve often thought that named graphs could provide an infrastructure for managing inferenced triples, and a recent Twitter exchange with Adrian Gschwend inspired me to follow through with a little demo.
There is a reasonable chance that you’ve never heard of SQLite and are unaware that this database management program and many database files in its format may be stored on all of your computing devices. Firefox and Chrome in particular use it to keep track of your cookies and, as I’ve recently learned, many other things. Of course I want to query all that data with SPARQL, so I wrote some short simple scripts to convert these tables of data to Turtle.
OpenStreetMap, or “OSM” to geospatial folk, is a crowd-sourced online map that has made tremendous achievements in its role as the Wikipedia of geospatial data. (The Wikipedia page for OpenStreetMap is really worth a skim to learn more about its impressive history.) OSM offers a free alternative to commercial mapping systems out there—and you better believe that the commercial mapping systems are reading that great free data into their own databases.
Last month I wrote about how we can treat the growing amount of JSON-LD in the world as RDF. By “treat” I mean “query it with SPARQL and use it with the wide choice of RDF application development tools out there”. While I did demonstrate that JSON-LD does just fine with URIs from outside of the schema.org vocabulary, the vast majority of JSON-LD out there uses schema.org.
I paid little attention to JSON-LD until recently. I just thought of it as another RDF serialization format that, because it’s valid JSON, had more appeal to people normally uninterested in RDF. Dan Brickley’s December tweet that “JSON-LD is much more widely used than Turtle” inspired me to look a little harder at the JSON-LD ecosystem, and I found a lot of great things. To summarize: the amount of JSON-LD data out there is exploding, and we can query it with SPARQL, so…
After I posted Reification is a red herring (and you don’t need property graphs to assign data to individual relationships) last month, I had an amusingly difficult time explaining to my wife how that would generate so much Twitter activity. This month I wanted to make it clear that I’m not opposed to reification in and of itself, and I wanted to describe the fun I’ve been having playing with Olaf Hartig and Bryan Thompson’s RDF* and and SPARQL* extensions to these…