Neo4j

https://dzone.com/articles/dynamic-rule-based-decision-trees-in-neo4j-part-2
http://www.sitepoint.com/efficient-user-timelines-php-application-neo4j/
http://www.sitepoint.com/create-neo4j-graph-database-using-rest-api
http://www.sitepoint.com/why-you-should-use-neo4j-in-your-next-ruby-app/
https://medium.com/@scbarrus/graphql-is-the-king-long-live-the-king-r-i-p-rest-cf04ce38f6c#.lym0dshvz