## Hidden gems included with Jena’s command line utilities

Lots of ways to manipulate your RDF from the open-source multiplatform tool kit

On page 5 of my book Learning SPARQL I described how the open source RDF processing framework Apache Jena includes command line utilities called arq and sparql that let you run SPARQL queries with a simple command line like this:

## Pulling Turtle RDF triples from the Google Knowledge Graph

Even querying by type!

When I wrote about my first deep dive into Knowledge Graphs, I mentioned that although the term was around well before 2012, the idea of a Knowledge Graph was blessed as an official Google thing that year when one of their engineering SVPs published the article Introducing the Knowledge Graph: things, not strings. This blessing gave some focus to many members of the graph database community because they could say that what they had been doing was similar, if not the same, as what Google was…

## Linking different knowledge graphs together

Really linking them, not doing ETL.

Lately I’ve been thinking about some aspects of RDF technology that I have taken for granted as basic building blocks of dataset design but that Knowledge Graph fans who are new to RDF may not be fully aware of—especially when they compare RDF to alternative ways to build knowledge graphs. A key building block is the ability to link independently created knowledge graphs.

## Transforming data with inferencing and (partial!) schemas

An excellent compromise between schemas and "schemaless" development.

I originally planned to title this “Partial schemas!” but as I assembled the example I realized that in addition to demonstrating the value of partial, incrementally-built schemas, the steps shown below also show how inferencing with schemas can implement transformations that are very useful in data integration. In the right situations this can be even better than SPARQL, because instead of using code—whether procedural or declarative—the transformation is driven by the data model…

## Knowledge Graphs!

Semantic Linked Knowledge Web Data Graphs?

For several years I thought of “knowledge graphs” as the buzzphrase that had partially replaced “Linked Data”, which was the buzzphrase that had partially replaced “Semantic Web”. In a 2012 blog entry I explained how Hadoop and the new-at-the-time NoSQL databases had convinced me that even if a technology has a funny name, selling it based on the problems it solves makes more sense and ages better than selling a buzz phrase vision and then, if that goes well,…

## Using SPARQL to combine Wikidata and OSM triples

I recently needed to join two datasets at work, cross-referencing one property in a spreadsheet with another in a JSON file. I used a combination of jq, perl, sort, uniq, and… I won’t go into details.