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Cypher for GremlinoCIM 4

Apache TinkerPop

Apache TinkerPop™ is a graph computing framework for both graph databases (OLTP) and graph analytic systems (OLAP).

Gremlin is a graph traversal language developed by Apache TinkerPop.

Gremlin in the wild

Gremlin in the wild

IBM Graph

Gremlin in the wild

IBM Graph

Gremlin in the wild

IBM Graph

Azure Cosmos DB

Gremlin in the wild

IBM Graph

Azure Cosmos DB

Amazon Neptune

Gremlin language

gremlin> g.V().count()==>0gremlin> g.addV('City').property('name', 'København')gremlin> g.V().count()==>1gremlin> g.V().hasLabel('City').values('name')==>København

Declarative vs imperative querying

// Cypher: what to getMATCH (b:Boat)-[:SAILS_TO]->(:Location {name: 'Denmark'})RETURN b

// Gremlin: how to get itg.V().hasLabel('Boat').as('b') .out('SAILS_TO') .hasLabel('Location').has('name', 'Denmark') .select('b')

Gremlin traversal

g.V().hasLabel('Boat').as('b') .out('SAILS_TO') .hasLabel('Location').has('name', 'Denmark') .select('b') .profile()

Step Count

TinkerGraphStep(vertex,[~label.eq(Boat)])@[b] 100000

VertexStep(OUT,[SAILS_TO],vertex) 100000

HasStep([~label.eq(Location), name.eq(Denmark)]) 1

SelectOneStep(last,b) 1

Gremlin traversal (the right way)

g.V().hasLabel('Location').has('name', 'Denmark') .in('SAILS_TO') .hasLabel('Boat') .profile()

Step Count

TinkerGraphStep(vertex,[~label.eq(Location), name.eq(Denmark)]) 1

VertexStep(IN,[SAILS_TO],vertex) 1

HasStep([~label.eq(Boat)]) 1

Cypher in Gremlin

// MATCH (b:Boat)-[:SAILS_TO]->(:Location {name: 'Denmark'})// RETURN b.name

g.V().hasLabel('Boat').as('b') .out('SAILS_TO') .hasLabel('Location').has('name', 'Denmark') .select('b').values('name')

==>"Havhingsten fra Glendalough"==>"Roar Ege"

Cypher in Gremlin: return columns

// MATCH (b:Boat)-[:SAILS_TO]->(:Location {name: 'Denmark'})// RETURN b.name

g.V().hasLabel('Boat').as('b') .out('SAILS_TO') .hasLabel('Location').has('name', 'Denmark') .select('b').project('b.name').by(values('name'))

==>{"b.name": "Havhingsten fra Glendalough"}==>{"b.name": "Roar Ege"}

Null handling in Gremlin

gremlin> g.addV('Boat').property('name', 'Roar Ege')==>v[0]gremlin> g.addV('Boat')==>v[1]gremlin> g.V().count()==>2gremlin> g.V().hasLabel('Boat').values('name')==>Roar Egegremlin> g.V().hasLabel('Boat').project('name').by(values('name'))==>[name:Roar Ege]The provided traverser does not map to a value: v[5]->[PropertiesStep([name],value)]

Cypher in Gremlin: nulls

// MATCH (b:Boat)-[:SAILS_TO]->(:Location {name: 'Denmark'})// RETURN b.name

g.V().hasLabel('Boat').as('b') .out('SAILS_TO') .hasLabel('Location').has('name', 'Denmark') .select('b').project('b.name').by( choose(neq('NULL'), coalesce(values('name'), constant('NULL')), constant('NULL')))

Cypher in Gremlin: traversal-based logic

// RETURN $a AND $b

g.inject('START').project('$a AND $b').by( choose( and(constant(a).is(eq(true)), constant(b).is(eq(true))), constant(true), choose( or(constant(a).is(eq(false)), constant(b).is(eq(false))), constant(false), constant('NULL'))))

Translation flow

82.5%731 scenarios

(with Server plugin)

Cypher TCK progress

● Functionality exclusive to Gremlin Servers with Cypher plugin:

○ List access by non-constant index

○ Map access

○ Non-numeric plus operator

○ Path comprehensions

○ Functions with non-native implementation: length, nodes, percentileCont, percentileDisc, properties,

relationships, size, toBoolean, toFloat, toInteger, toString

● Multiple labels and label modification are not supported

○ TinkerPop graph elements have a single, immutable string label

○ No plans for a workaround

Major limitations

Cypher for Gremlin integration

Gremlin Serverwithout Cypher plugin

Gremlin Serverwith Cypher plugin

Gremlin driver ❌ ✔ server-side translation

Cypher Gremlin clientfor Java ✔ client-side translation ✔ server-side translation

Gremlin Console ❌ ❌

Gremlin Consolewith Cypher plugin ✔ client-side translation ✔ server-side translation

It’s on GitHub!

https://github.com/opencypher/cypher-for-gremlin

● Cypher to Gremlin translation library for Java

● Cypher plugin for Gremlin Server

● Cypher plugin for Gremlin Console

● Cypher wrapper for Gremlin client

● Neo4j driver API wrapper

● TCK implementation for Gremlin

It’s on GitHub!

https://github.com/opencypher/cypher-for-gremlin

Java APIs: translation

String cypher = "MATCH (p:Person) WHERE p.age > 25 RETURN p.name";CypherAstWrapper ast = CypherAstWrapper.parse(cypher);

Translator<String, GroovyPredicate> translator =Translator.builder().gremlinGroovy().build();

String gremlin = ast.buildTranslation(translator);

Java APIs: Gremlin Server client

Cluster cluster = Cluster.open(configuration);Client gremlinClient = cluster.connect();CypherGremlinClient cypherGremlinClient =

CypherGremlinClient.translating(gremlinClient);

String cypher = "MATCH (p:person) WHERE p.age > 25 RETURN p.name";CypherResultSet resultSet = cypherGremlinClient.submit(cypher);List<Map<String, Object>> results = resultSet.all();

Java APIs: Neo4j driver

Config config = Config.build() .withTranslation() .toConfig();Driver driver = GremlinDatabase.driver("//localhost:8182", config);

String cypher = "MATCH (p:person) WHERE p.age > 25 RETURN p.name";try (Session session = driver.session()) { StatementResult result = session.run(cypher); List<Record> records = result.list();}

Java APIs: In-memory graphs

TinkerGraph graph = TinkerFactory.createModern();GraphTraversalSource traversal = graph.traversal();

// Gremlin Server clientCypherGremlinClient cypherGremlinClient = CypherGremlinClient.inMemory(traversal);

// Neo4j driverDriver driver = GremlinDatabase.driver(traversal);

Java APIs: In-memory graphs

// SimpleGraph ExcelExcelSystem excelSystem = new ExcelSystem();excelSystem.connect();excelSystem.moveTo(new File("graph.xlsx").toURI().toString());GraphTraversalSource traversal = excelSystem.g();

CypherGremlinClient cypherGremlinClient = CypherGremlinClient.inMemory(traversal);

Quick start

// Add dependenciescompile "org.apache.tinkerpop:tinkergraph-gremlin:3.3.2"compile "org.opencypher.gremlin:cypher-gremlin-neo4j-driver:0.9.6"

// Create an in-memory graphTinkerGraph graph = TinkerFactory.createModern();GraphTraversalSource traversal = graph.traversal();Driver driver = GremlinDatabase.driver(traversal);

// Query as usual: driver.session()... etc// (Except transactions)