This project was a POC and is no longer maintained. However, a maintained fork can be found right here:

https://github.com/LITMUS-Benchmark-Suite/sparql-to-gremlin

image::https://raw.githubusercontent.com/dkuppitz/sparql-gremlin/master/docs/images/sparql-gremlin-logo.png[SPARQL-Gremlin]

SPARQL-Gremlin

SPARQL-Gremlin is a compiler used to transform SPARQL queries into Gremlin traversals. It is based on the https://jena.apache.org/index.html[Apache Jena] SPARQL processor https://jena.apache.org/documentation/query/index.html[ARQ], which provides access to a syntax tree of a SPARQL query.

The current version of SPARQL-Gremlin only uses a subset of the features provided by Apache Jena. The examples below show each implemented feature.

Quick Start

Console Application

The project contains a console application that can be used to compile SPARQL queries and evaluate the resulting Gremlin traversals. For usage examples simply run `${PROJECT_HOME}/bin/sparql-gremlin.sh`.

Gremlin Shell Plugin

To use Gremlin-SPARQL as a Gremlin shell plugin, run the following commands (be sure sparql-gremlin-xyz.jar is in the classpath):

[source]

gremlin> :install com.datastax sparql-gremlin 0.1 ==>Loaded: [com.datastax, sparql-gremlin, 0.1] gremlin> :plugin use datastax.sparql ==>datastax.sparql activated

Once the plugin is installed and activated, establish a remote connection to execute SPARQL queries:

[source]

gremlin> :remote connect datastax.sparql graph ==>SPARQL[graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]] gremlin> :> SELECT ?name ?age WHERE { ?person v:name ?name . ?person v:age ?age } ==>[name:marko, age:29] ==>[name:vadas, age:27] ==>[name:josh, age:32] ==>[name:peter, age:35]

Prefixes

SPARQL-Gremlin supports the following prefixes to traverse the graph:

[options="header"] |================= |Prefix |Purpose |e:<label> |out-edge traversal |p:<name> |property traversal |v:<name> |property-value traversal |=================

Note that element IDs and labels are treated like normal properties, hence they can be accessed using the same pattern:

[source]

SELECT ?name ?id ?label WHERE { ?element v:name ?name . ?element v:id ?id . ?element v:label ?label }

Examples

Select All

.Select all vertices in the graph.
[source,SPARQL]
----
SELECT * WHERE {
}
----

Match Constant Values

.Select all vertices with the label person. [source,SPARQL]

SELECT * WHERE { ?person v:label "person" }

Select Specific Elements

.Select the values of the properties `name` and `age` for each `person` vertex.
[source,SPARQL]
----
SELECT ?name ?age
WHERE {
  ?person v:label "person" .
  ?person v:name ?name .
  ?person v:age ?age
}
----

Pattern Matching
~~~~~~~~~~~~~~~~

.Select only those persons who created a project.
[source,SPARQL]
----
SELECT ?name ?age
WHERE {
  ?person v:label "person" .
  ?person v:name ?name .
  ?person v:age ?age .
  ?person e:created ?project
}
----

Filtering
~~~~~~~~~

.Select only those persons who are older than 30.
[source,SPARQL]
----
SELECT ?name ?age
WHERE {
  ?person v:label "person" .
  ?person v:name ?name .
  ?person v:age ?age .
  ?person e:created ?project .
    FILTER (?age > 30)
}
----

Deduplication
~~~~~~~~~~~~~

.Select the distinct names of the created projects.
[source,SPARQL]
----
SELECT DISTINCT ?name
WHERE {
  ?person v:label "person" .
  ?person e:created ?project .
  ?project v:name ?name .
    FILTER (?age > 30)
}
----

Multiple Filters
~~~~~~~~~~~~~~~~

.Select the distinct names of all Java projects.
[source,SPARQL]
----
SELECT DISTINCT ?name
WHERE {
  ?person v:label "person" .
  ?person e:created ?project .
  ?project v:name ?name .
  ?project v:lang ?lang .
    FILTER (?age > 30 && ?lang == "java")
}
----

Pattern Filter
~~~~~~~~~~~~~~

.A different way to filter all person who created a project.
[source,SPARQL]
----
SELECT ?name
WHERE {
  ?person v:label "person" .
  ?person v:name ?name .
    FILTER EXISTS { ?person e:created ?project }
}
----

.Filter all person who did not create a project.
[source,SPARQL]
----
SELECT ?name
WHERE {
  ?person v:label "person" .
  ?person v:name ?name .
    FILTER NOT EXISTS { ?person e:created ?project }
}
----

Meta-Property Access
~~~~~~~~~~~~~~~~~~~~

[source,SPARQL]
----
SELECT ?name ?startTime
WHERE {
  ?person v:name "daniel" .
  ?person p:location ?location .
  ?location v:value ?name .
  ?location v:startTime ?startTime
}
----