hydra-pg 0.16.0

Property graph support for Hydra

Hydra-PG

hydra-pg is the translingual support package for the property graph data model in Hydra. It is generated into Haskell, Java, and Python from a common set of DSL sources, and depends on hydra-kernel and hydra-rdf.

For background on Hydra's approach to property graphs, see the Property graphs wiki page.

What it provides

• PG data model — vertices, edges, properties, and graph schemas, with a coder that maps Hydra types and terms onto graph elements.
• GraphSON coder — emits TinkerPop-compatible GraphSON 3.0 from Hydra-PG graphs.
• Cypher syntax model — the openCypher grammar plus Cypher feature/function metadata.
• GQL syntax model — the ISO/IEC GQL grammar and a path-algebra syntax model.
• TinkerPop syntax model — Gremlin grammar plus TinkerPop feature metadata.
• Graphviz coder and DOT serializer — for rendering property graphs as diagrams.
• PG-to-RDF mappings — produces RDF descriptions of property-graph vertices and edges, for use with hydra-rdf.
• PG validator — checks property graphs against a schema; runs identically across Haskell, Java, and Python.

Demos

Four demos exercise this package end-to-end:

• demos/avro — bidirectional Avro coder; one of its modes maps Avro data to a TinkerPop-annotated property graph and emits GraphSON.
• demos/genpg — generates a property graph from relational CSV data and emits it as either GraphSON or RDF/SHACL N-Triples.
• demos/pg-formats — shows three views of the TinkerPop "Modern" reference graph: Hydra-PG JSON, GraphSON 3.0, and JSON Schema.
• demos/validatepg — translingual property-graph validation, running the same Hydra validation logic in Haskell, Java, and Python.

See also

• HydraPop — translingual extensions for Apache TinkerPop, built on top of this package.