History

• Originally called Titan. It was renamed to JanusGraph in 2015.

Data Model

Query Interface

JanusGraph uses Gremlin graph query language to retrieve data from and modify data in the graph. Gremlin is a functional language whereby traversal operators are chained together to form path-like expressions, expressing query or data modification on graphs.

A Gremlin query is a chain of operations/functions that are evaluated from left to right. A simple example of gremlin language to query the name of Alex's grandson on his genealogy graph is provided below

g.V().has('name', 'Alex').out('father').out('father').values('name')

The query can be read as

g: for the current graph

V: for the vertices in the graph

has('name', 'Alex'): filters the vertices down to those with the "name" property "Alex"

out('father'): traverse outgoing through edges whose type is "father" from "Alex" (Notice here the result can be more than one vertices)

out('father'): traverse outgoing through edges whose type is "father" from "Alex"' son (the result from the last traversal)

values('name'): get the property of "name"