Neo4j-core 
This gem only contains the JRuby mapping of the Neo4j graph database and does not wrap nodes and relationship in ruby objects. The neo4j.rb gem consists of three gems, neo4j-core, neo4j-wrapper and neo4j. This gem contains two modules: Neo4j and Neo4j::Core The Neo4j module is public and the Neo4j::Core(::*) are internal modules.
Documentation
The public API
Neo4j::Node The Java Neo4j Node
Neo4j::Relationship The Java Relationship
Neo4j The Database
Neo4j::Cypher} Cypher Query DSL, see Wiki
{Neo4j::Algo Included algorithms, like shortest path
License
-
Neo4j.rb - MIT, see the LICENSE file github.com/andreasronge/neo4j-core/tree/master/LICENSE.
-
Lucene - Apache, see lucene.apache.org/java/docs/features.html
-
Neo4j - Dual free software/commercial license, see neo4j.org/
Notice there are different license for the neo4j-community, neo4j-advanced and neo4j-enterprise jar gems. Only the neo4j-community gem is by default required.
