Implementation of graph database for OpenCog artificial general intelligence framework using Neo4j

We create a graph backing store[1l for OpenCog[2, 3, 26, 27, 28] using Neo4j graph database[4]. The GraphBackingStore API extends the current BackingStore C++ API. It can take special queries that map naturally into Cypher queries and simple manipulations of Neo4j graph traversals. The Neo4j node-relationship structures and custom indices are optimized for AtomSpace[5] usage and performance, with considerations for integration with Linked Data[17]. This makes it easier to integrate projects which use common Linked Data foundation, such as Lumen Robot Friend[29]. Data access is using Protocol Buffers-based[6] protocol over ZeroMQ[7] messaging transport. The initial work for Neo4j Graph Backing Store for OpenCog was implemented during Google Summer of Code 2015[8]. All source code is open source and available at https://github.com/ceefour/opencog-neo4j, https://github.com/opencog/atomspace, andhttps://github.com/opencog/opencog.