A Preview of Stardog 4

Jul 15, 2015, 3 minute read
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Let’s preview the big changes coming in Stardog 4. Watch this space for the release soon.

Gremlin Joins SPARQL

Stardog 4 supports property graphs, Gremlin, and TinkerPop 3. Stardog is now a polyglot graph database and handles both RDF and property graphs. In fact Stardog is the only graph system that exposes the full power of rules and OWL reasoning to graph traversals and the property graph model generally.

Apache TinkerPop is the de facto API for property graph implementations, and Gremlin is a DSL for traversing graphs. Gremlin is to property graphs as SPARQL is to RDF graphs.

Stardog users understand that smart graphs are better than dumb graphs and that smart data is better than smart code. They want to query and traverse (and search and learn and…) semantic graphs, which is why Stardog 4’s support for Gremlin including rules and axiomatic reasoning.

Namespace-less Mode

Our property graph friends don’t use URIs for node or edge labels; and sometimes even semantic graph applications don’t really need to pay that cost upfront. Stardog already supported stored namespaces and using these namespaces in SPARQL queries without prefix declarations making it easier to work with URIs.

Stardog 4 supports omitting namespace declarations in RDF files as well. Namespaces for RDF, RDFS, OWL, and XSD vocabularies are automatically added to Stardog databases along with a default namespace making it possible to insert, delete, and query data without any prefix declarations at all.

Virtual Graphs and Enterprise Integration

Stardog 4 supports Virtual Graphs for enterprise integration. In the enterprise, where the data comes from is an important consideration. Put another way, the relationship between systems of record data and graph data is crucial and largely ignored in graph databases. Stardog takes this relationship to be central: it can model (and integrate and analyze) data that lives in non-graph (and graph!) systems of record.

Stardog 4 virtual graphs support declarative mappings of any JDBC-accessible RDBMS into a Stardog graph with query-time instatiation of the mappings.

The real potential of graph databases is integrating hetereogenous enterprise data to reduce the cost and increase the quality of analytics.

Geospatial Query

Stardog 4 includes geospatial query support. Graph data that uses the WGS 84 or OGC GeoSPARQL vocabulary to encode latitude & longitude will trigger Stardog 4 to spatially index every geo:Feature it can find. Then you can do geo:relate, geo:distance, geo:within, and geo:area, etc. in SPARQL queries.

All of this is user extensible by grabbing JTS and dropping the JAR into the classpath, then setting spatial.use.jts=true, which enables WKT shapes, including polygons, etc.

What does it look like? Check it out.

Java 8

Stardog 4 requires Java 8 and will not work with an earlier version of Java. Java 6 and 7 are officially dead. So we jumped all the way to Java 8, especially since it offers some new capabilities we were dying to bake into Stardog like lambdas, parallelism, streams, etc.

Core API Changes

Stardog 4 includes core API changes. Some of these changes are to take advantage of Java 8 features like Stream and java.nio.file#Path. Others are cleanups to move Stardog to RDF 1.1.

What’s Next?

In the 4.1 we’ll release Pelorus—our faceted graph browser—integrated into the Stardog Web Console. Then in the remainder of the 4.x release cycle we’ll focus on scalability, HDFS integration, SPARQL performance, and refinement of existing capabilities.

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