Neo4j for Java Developers

All about the „4j“Michael.Hunger@Neo4j.org

(Michael)-[:WORKS_FOR]->(Neo4j)

michael@neo4j.org | @mesirii | github.com/jexp | jexp.de/blog

Michael Hunger - Community Caretaker @Neo4j

• From Pain to Graph• Graphs Are Everywhere• For once no Java Haters• Demo(s)!• Q&A

Today‘s Entertainment

Once Upon A Time in SwedenOnce Upon a Time in Sweden

Solution

History of Neo4j

• 0.x ... small embeddable persistent graph library

• 1.x ... adding indexes, server, first stab of Cypher

• 2.x ... ease of use, data-model, optional schema, cost based optimizer, import, Neo4j-Browser

• 3.x …binary protocol, bytecode compiled queries,sharding

(graphs)-[:ARE]->(everywhere)

Value from Data RelationshipsCommon Use Cases

Internal ApplicationsMaster Data Management

Network and IT Operations

Fraud Detection

Customer-Facing ApplicationsReal-Time Recommendations

Graph-Based SearchIdentity and

Access Management

http://neo4j.com/use-cases

The Whiteboard Model Is the Physical Model

CAR

DRIVES

name: "Dan"born: May 29, 1970

twitter: "@dan"name: "Ann"

born: Dec 5, 1975

since: Jan 10, 2011

brand: "Volvo"model: "V70"

Property Graph Model

Nodes• The objects in the graph• Can have name-value properties• Can be labeled

Relationships• Relate nodes by type and direction• Can have name-value properties

LOVES

LOVES

LIVES WITH

OWN

S

PERSON PERSON

http://neo4j.com/developer/graph-database/#property-graph

Relational to Graph

Relational Graph

KNOWS

KNOWS

KNOWS

ANDREAS

TOBIAS

MICA

DELIA

Person FriendPerson-Friend

ANDREASDELIA

TOBIAS

MICA

http://neo4j.com/developer/graph-db-vs-rdbms/

Neo4j: All About Patterns

(:Person { name:"Dan"} ) -[:LOVES]-> (:Person { name:"Ann"} )

LOVES

Dan Ann

LABEL PROPERTY

NODE NODE

LABEL PROPERTY

http://neo4j.com/developer/cypher

Cypher: Find Patterns

MATCH (:Person { name:"Dan"} ) -[:LOVES]-> (love:Person) RETURN love

LOVES

Dan ?

LABEL

NODE NODE

LABEL PROPERTY ALIAS ALIAS

http://neo4j.com/developer/cypher

Demo

http://neo4j.com/developer/guide-neo4j-browser

Neo4j from Java

Good Old Days

<dependency> <groupId>org.neo4j</groupId> <artifactId>neo4j</artifactId> <version>2.2.5</version></dependency>

Neo4j‘s Java API

GraphDatabaseService db = ...Node dan= db.createNode(Person);dan.setProperty("name","Dan");

Relationship rel = dan.createRelationshipTo(ann,LOVES);rel.setProperty("how","very");db.shutdown();

http://neo4j.com/docs/stable/tutorials-java-embedded.html

Neo4j is Transactional

GraphDatabaseService db = ...try (Transaction tx = db.beginTx()) { Node dan = ... Node ann = ... Relationship rel = ... tx.success();}db.shutdown();

Heavy Lifting - Demo

https://gist.github.com/jexp/a54cfa99a1028743858e

Extend Neo4j Server

Extend Neo4j Server

@Path( "/meta" )public class MetaInfoResource { @GET @Produces( MediaType.APPLICATION_JSON ) @Path( "/{node}" ) public Response meta(@PathParam("node") long id, @Context GraphDatabaseService db) {

Iterable labels = db.getNodeById(id).getLabels(); return Response.status( OK ).entity( labels ).build(); }}

http://neo4j.com/docs/stable/server-unmanaged-extensions.html

Cypher from Java

Running Cypher from Javaquery = "MATCH (:Person {name:{name}})-[:LOVES]->(p) RETURN p.name AS loved";params = map("name", "Dan");

try (result = db.execute(query, params)) { for (Map row : result) { row.get("loved"); }} http://neo4j.com/docs/stable/tutorials-cypher-java.html

Running Cypher from Java - Remoteurl = "http://.../db/data/transaction/commit";query = "MATCH ... RETURN loved";params = map("name", "Dan");

r = HTTP.POST(url,"{statements: [{statement:query, parameters:params}]}")r.status() == 200r.content().get("errors") == []r.content().get("results").get(0) ==[{"columns":["loved"],"data": [{"row": ["Ann"]}]}] http://neo4j.com/docs/stable/rest-api-transactional.html

Connect via JDBCconn = driver.connect("jdbc:neo4j://localhost:7474");PreparedStatement ps = conn.prepareStatement(" MATCH (:Person {name:{1}})-[:LOVES]->(loved) RETURN loved.name as loved");

ps.setLong(1,"Dan");ResultSet rs = ps.executeQuery();

while (rs.next()) { rs.getString("loved");} http://neo4j.com/developer/java/#neo4j-jdbc

Database-Tools, ETL, BI-Tools

JVM Languages

Clojure - neocons(ns neocons.docs.examples (:require [clojurewerkz.neocons.rest :as nr] [clojurewerkz.neocons.rest.cypher :as cy]))(defn -main [& args] (nr/connect! "http://host:port/db/data/") (let [query "MATCH (:Person {name:{name}})-[:LOVES]->(loved) RETURN lover.name as loved" res (cy/tquery query {:name "Dan"})] (println res))) http://neo4j.com/developer/clojure

Scala (AnormCypher – Spark)

import org.anormcypher._import org.apache.spark.graphx._

val dbConn = Neo4jREST("localhost", 7474, "/db/data/")val q = """MATCH (p1:Page)-[:Link]->(p2) RETURN id(p1) AS from, id(p2) AS to LIMIT 100000000"""val r = Cypher(q).apply()(dbConn)val links = sc.parallelize(r,100).map( Edge(row[Int]("from").toLong,row[Int]("to").toLong, None)) links.count

http://neo4j.com/developer/scala

Groovy – Batch-Import@Grab('org.neo4j:neo4j:2.2.5')import org.neo4j.graphdb.*

batch = BatchInserters.inserter(store,config)for (line in parseCsv(csv)) { author = batch.createNode([name:line.author],Labels.Author) article= batch.createNode( [title:line.title, date:date],Labels.Article) batch.createRelationship(author,article, WROTE, NO_PROPS)}batch.createDeferredSchemaIndex(Labels.Article) .on("title").create()http://jexp.de/blog/2014/10/flexible-neo4j-batch-import-with-groovy

Convenient Object Graph Mapping

Spring Data Neo4j@NodeEntity class Person { @GraphId Long id; String name; @Relationship(type="LOVES") Person loved;}

interface PersonRepository extends GraphRepository<Person> { @Query("MATCH ... RETURN loved") Set<Person> findLoved(String person)}

https://neo4j.com/developer/spring-data-neo4j

Spring Data Neo4j@EnableNeo4jRepositories(basePackages="sample.repositories")public class MyNeo4jConfiguration extends Neo4jConfiguration {

@Bean public Neo4jServer neo4jServer() { return new RemoteServer(System.getenv("NEO4J_URL")); }

@Bean public SessionFactory getSessionFactory() { return new SessionFactory("sample.domain"); }}

Spring Data Neo4j

@RelationshipEntity(type="LOVES")class Love { @GraphId Long id; @StartNode Person lover; @EndNode Person loved; Date since;}

https://github.com/spring-projects/spring-boot/pull/3899

Demo(s)

The Sky is the Limit

Learn More

http://neo4j.com/developer/resources

Thank YouQuestions ? Books!

michael@neo4j.org@mesirii