There are many ways to use Neo4j from Java. In this talk I want to demonstrate different APIs and examples on how to build solutions on top of Neo4j using a Java based stack.

1. Neo4j for Java Developers
All about the „4j“
Michael.Hunger@Neo4j.org

2. (Michael)-[:WORKS_FOR]->(Neo4j)
michael@neo4j.org | @mesirii | github.com/jexp | jexp.de/blog
Michael Hunger - Community Caretaker @Neo4j

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

4. Once Upon A Time in Sweden
Once Upon a Time in Sweden

5. Solution

6. 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

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

8. Value from Data Relationships
Common Use Cases
Internal Applications
Master Data Management
Network and
IT Operations
Fraud Detection
Customer-Facing Applications
Real-Time Recommendations
Graph-Based Search
Identity and
Access Management

9. The Whiteboard Model Is the Physical Model

10. CAR
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
PERSON PERSON

11. Relational to Graph
Relational Graph
KNOWS
ANDREAS
TOBIAS
MICA
DELIA
Person FriendPerson-Friend
ANDREAS
DELIA
TOBIAS
MICA

12. Neo4j: All About Patterns
(:Person { name:"Dan"} ) -[:LOVES]-> (:Person { name:"Ann"} )
LOVES
Dan Ann
LABEL PROPERTY
NODE NODE
LABEL PROPERTY

13. Cypher: Find Patterns
MATCH (:Person { name:"Dan"} ) -[:LOVES]-> (love:Person) RETURN love
LOVES
Dan ?
LABEL
NODE NODE
LABEL PROPERTY ALIAS ALIAS

14. Demo

15. Neo4j from Java

16. Good Old Days
<dependency>
<groupId>org.neo4j</groupId>
<artifactId>neo4j</artifactId>
<version>2.2.5</version>
</dependency>

17. 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();

18. Neo4j is Transactional
GraphDatabaseService db = ...
try (Transaction tx = db.beginTx()) {
Node dan = ...
Node ann = ...
Relationship rel = ...
tx.success();
}
db.shutdown();

19. Heavy Lifting - Demo

20. Extend Neo4j Server

21. 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();
}
}

22. Cypher from Java

23. Running Cypher from Java
query =
"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");
}
}

24. Running Cypher from Java - Remote
url = "http://.../db/data/transaction/commit";
query = "MATCH ... RETURN loved";
params = map("name", "Dan");
r = HTTP.POST(url,"{statements:
[{statement:query, parameters:params}]}")
r.status() == 200
r.content().get("errors") == []
r.content().get("results").get(0) ==
[{"columns":["loved"],"data": [{"row": ["Ann"]}]}]

25. Connect via JDBC
conn = 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");
}

26. Database-Tools, ETL, BI-Tools

27. JVM Languages

28. 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)))

29. 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

30. 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()

31. Convenient Object Graph Mapping

32. 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)
}

33. 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");
}
}

34. Spring Data Neo4j
@RelationshipEntity(type="LOVES")
class Love {
@GraphId Long id;
@StartNode Person lover;
@EndNode Person loved;
Date since;
}

36. Demo(s)

37. The Sky is the Limit

38. Learn More

39. Thank You
Questions ? Books!
michael@neo4j.org
@mesirii