For consistency with other Blueprints implementations, it would be great to open OrientDB graphs with local engine by default (when the engine is not specified).
gremlin> g = new OrientGraph('../data/orient/tinkergraph')
Error in database URL: the engine was not specified. Syntax is: <engine>:<db-type>:<db-name>[?<db-param>=<db-value>[&]]*. URL was: ../data/orient/tinkergraph
Display stack trace? [yN]
gremlin> g = new OrientGraph('local:../data/orient/tinkergraph')
==>orientgraph[local:../data/orient/tinkergraph]