Introducing Neo4j SDN⚡️RX

Neo4j SDN⚡RX „What the hell, it’s 2020 and you’re writing
a new object mapping framework?“ 15th May 2020 Michael Simons introducing

Neo4j SDN⚡ RX at Spring I/O Bridge 2020 by @rotnroll666
Agenda • About Neo4j • Who are the folks working on the Object mapping things? • Some history • SDN/RX • What do we want? • New building blocks for Spring Boot • Neo4j Client, Template and Repositories • Cypher DSL 2

About Neo4j

Ecosystem Neo4j Professional Services 300+ partners 47,000 group members 61,000
trained engineers 3.5M downloads Mindset “Graph Thinking” is all about considering connections in data as important as the data itself. Native Graph Platform Neo4j is an internet-scale, native graph database which executes connected workloads faster than any other database management system. Neo4j 4

Who are the folks working on the object mapping things?

Team SDN+OGM (Object Graph Mapping) 6

• Neo4j since July 2018 • Java Champion • Co-Founder and current lead of Java User Group EuregJUG • Author (Spring Boot 2 und Arc42 by example) About me 7 First contact to Neo4j through

Some history

9 It’s a kind of magic? Custom Spring Boot Starter Michael Simons @rotnroll666

WITH previous_month AS (SELECT p.track_id, count(*) as cnt, dense_rank() over(order
by count(*) desc) as position FROM plays p WHERE trunc(p.played_on, 'DD') BETWEEN date'2016-04-01' and date'2016-04-30' GROUP BY p.track_id), current_month AS (SELECT p.track_id, count(*) as cnt, dense_rank() over(order by count(*) desc) as position FROM plays p WHERE trunc(p.played_on, 'DD') BETWEEN date'2016-05-01' and date'2016-05-31' GROUP BY p.track_id) SELECT a.artist !" ' - ' !" t.name !" ' (' !" t.album !" ')' as label, current_month.cnt, previous_month.position - current_month.position as change FROM tracks t JOIN artists a on a.id = t.artist_id JOIN current_month current_month on current_month.track_id = t.id LEFT OUTER join previous_month on previous_month.track_id = t.id ORDER BY current_month.cnt desc, label asc FETCH FIRST 20 ROWS ONLY;

Tracking musical data (at Spring I/O 2017)

Known for 11

12 Diﬀerent approaches • Just query what’s needed • Use special database functions • Work on aggregates • Use analytic queries • Or graph queries Some examples to follow…

13 © https://www.enerko-informatik.de/projekte/ihl/ © https://www.enerko-informatik.de/produkte/ensupply/ Both backed by a relational database…

14 https://github.com/michael-simons/bootiful-music Backed by Neo4j

15 https://github.com/michael-simons/bootiful-music Backed by Neo4j

16 Current Spring Data Neo4 + OGM • start.spring.io gives you SDN and OGM • 3 diﬀerent modes available (Embedded, HTTP and native) • Custom queries are possible but go all through the OGM abstraction • Some building parts stack vertically, some horizontally ➡ Confusing options for beginners

Neo4j SDN⚡RX

What do we want?

19 What do we want? • A composable stack • Nicely integrated in Spring Boot • Access at all abstraction levels • Raw queries (outside application level transactions) • Raw queries (inside application level transactions) • Plus ad-hoc mapping • Mapping • Repository abstraction • Reactive (and imperative) database access

20 A composable stack

21 Spring Boot starter revisited <dependency> <groupId>org.neo4j.driver!#groupId> <artifactId>neo4j-java-driver-spring-boot-starter!#artifactId> <version>4.0.1.1!#version> !#dependency> Gives you: • Dependencies • spring.factories • Conﬁguration properties • Automatic conﬁguration

@ConfigurationProperties(prefix = "org.neo4j.driver") public class Neo4jDriverProperties { public static class Authentication { /** The login of the user connecting to the database.!% private String username; /** The password of the user connecting to the database. !% private String password; /** The realm to connect to.!% private String realm; } /** The uri this driver should connect to. The driver supports bolt or neo4j as schemes.!% private URI uri; /** The authentication the driver is supposed to use. Maybe null. !% private Authentication authentication = new Authentication(); } 22 Property mapping

23 Automatic conﬁguration for the Driver @Configuration(proxyBeanMethods = false) @AutoConfigureBefore(Neo4jDataAutoConfiguration.class) @ConditionalOnClass(Driver.class) @EnableConfigurationProperties(Neo4jDriverProperties.class) @Import({ DriverConfiguration.class, AdditionalDataConfiguration.class }) public class Neo4jDriverAutoConfiguration { } @Configuration(proxyBeanMethods = false) class DriverConfiguration { @Bean @ConditionalOnMissingBean(Driver.class) @ConditionalOnProperty(prefix = "org.neo4j.driver", name = "uri") Driver neo4jDriver(final Neo4jDriverProperties driverProperties) { final AuthToken authToken = driverProperties.getAuthentication().asAuthToken(); final Config config = driverProperties.asDriverConfig(); return GraphDatabase.driver(driverProperties.getUri(), authToken, config); } }

24 Automatic conﬁguration for the Driver • Spring Boot 2.2 got enhanced to recognise the presence of a Driver-Bean!

<dependency> <groupId>org.neo4j.springframework.data!#groupId> <artifactId>spring-data-neo4j-rx-spring-boot-starter!#artifactId> <version>1.0.1!#version> !#dependency> 25 Similar starter for SDN/RX

Moving upwards on abstraction levels

27 @Autowired org.neo4j.driver.Driver @RestController public class MoviesController { private final Driver driver; public MoviesController(Driver driver) { this.driver = driver; } @GetMapping(path = "/movies", produces = MediaType.TEXT_EVENT_STREAM_VALUE) public Flux<String> getMovieTitles() { !& Using an implicit, driver managed transaction return Flux.usingWhen( Mono.fromSupplier(driver!'rxSession), s !( Flux.from(s.run("MATCH (m:Movie) RETURN m ORDER BY m.name ASC").records()), RxSession!'close ).map(r !( r.get("m").asNode().get("title").asString()); } }

27 @Autowired org.neo4j.driver.Driver @RestController public class MoviesController { private final Driver driver; public MoviesController(Driver driver) { this.driver = driver; } @GetMapping(path = "/movies", produces = MediaType.TEXT_EVENT_STREAM_VALUE) public Flux<String> getMovieTitles() { !& Using an implicit, driver managed transaction return Flux.usingWhen( Mono.fromSupplier(driver!'rxSession), s !( Flux.from(s.run("MATCH (m:Movie) RETURN m ORDER BY m.name ASC").records()), RxSession!'close ).map(r !( r.get("m").asNode().get("title").asString()); } } Based on open standards: Reactive Streams. Can be used with RxJava2, too.

@Service public class MovieService { private final ReactiveNeo4jClient client; public MovieService(ReactiveNeo4jClient client) { this.client = client; } !& Fully integrated with Springs declarative !& or explicit transactions (via TransactionalOperator or TransactionTemplate) @Transactional public Flux<String> getMovieTitles() { return client.query("MATCH (m:Movie) RETURN m ORDER BY m.name ASC") .fetchAs(String.class) .mappedBy((typeSystem, record) !( record.get("m").asNode().get("title").asString()) .all(); } } 28 @Autowired org.neo4j.s…k.data.core.ReactiveNeo4jClient

29 @Autowired org.neo4j.s…k.data.core.ReactiveNeo4jTemplate @Service public class MovieService { private final ReactiveNeo4jTemplate template; public MovieService(ReactiveNeo4jTemplate template) { this.template = template; } @Transactional public Flux<String> getMovieTitles() { !& Overload with custom query available return template.findAll(MovieEntity.class) .map(MovieEntity!'getTitle); } } @Node("Movie") class MovieEntity { private @Id final String title; private @Property("tagline") final String description; @Relationship(type = "ACTED_IN", direction = INCOMING) private final Map<PersonEntity, Roles> actorsAndRoles; !& Full immutable class, works also with @Data, !& Kotlin and JDK 14 records public MovieEntity(String title, String description, Map<PersonEntity, Roles> actorsAndRoles ) { this.title = title; this.description = description; this.actorsAndRoles = actorsAndRoles; } }

public interface MovieRepository extends ReactiveNeo4jRepository<MovieEntity, String> {} @Service public class MovieService { private final MovieRepository repository; public MovieService(MovieRepository repository) { this.repository = repository; } @Transactional public Flux<String> getMovieTitles() { !& Custom query via @Query on a method !& For simple cases, use derived query methods !& repository.findAllByOrderByTitle return repository.findAll() .map(MovieEntity!'getTitle); !& For the first time with Spring Data and Neo4j, query by Example !& return repository.findAll(Example.of(new MovieEntity("The Matrix", null))); } } 30 @Autowired org.neo4j.s…k.data.core.ReactiveNeo4jRepository

And more…

32 Non-functional concerns • Compose only vertically • Less surprises • No smart guess, better fail fast • „When in Spring land, do as the Spring Data team does“ • Well deﬁned extension points for • Custom queries • Adhoc mappings

33 No more string concatenation: CypherDSL • Started as internal API • Heavily inspired by both jOOQ and Spring Data JDBC • Compile-time checked query construction • Used internally for every query generated

34 No more string concatenation: CypherDSL var tom = node("Person").named("tom").properties("name", literalOf("Tom Hanks")); var coActors = anyNode("coActors"); var cocoActors = anyNode("cocoActors"); var strength = count(asterisk()).as("Strength"); var statement = Cypher .match( tom.relationshipTo(anyNode("m"), "ACTED_IN").relationshipFrom(coActors, "ACTED_IN"), coActors.relationshipTo(anyNode("m2"), "ACTED_IN").relationshipFrom(cocoActors, "ACTED_IN") ) .where(not(tom.relationshipTo(anyNode(), "ACTED_IN").relationshipFrom(cocoActors, "ACTED_IN"))) .and(tom.isNotEqualTo(cocoActors)) .returning( cocoActors.property("name").as("Recommended"), strength ).orderBy(strength.asName().descending()) .build(); assertThat(cypherRenderer.render(statement)) .isEqualTo("" + "MATCH " + "(tom:`Person` {name: 'Tom Hanks'})-[:ÀCTED_IN`]"#(m)"$[:ÀCTED_IN`]-(coActors), " + "(coActors)-[:ÀCTED_IN`]"#(m2)"$[:ÀCTED_IN`]-(cocoActors) " + "WHERE (NOT (tom)-[:ÀCTED_IN`]"#()"$[:ÀCTED_IN`]-(cocoActors) AND tom "% cocoActors) " + "RETURN cocoActors.name AS Recommended, count(*) AS Strength ORDER BY Strength DESC");

Available now

36 mkdir bootiful-music !) cd bootiful-music npm install -g generator-jhipster curl -L https:!&r.neo4j.com/hipster-music -o bootiful-music.jh jhipster import-jdl bootiful-music.jh docker-compose -f src/main/docker/neo4j.yml up -d ./mvnw https://medium.com/neo4j/two-hip-friends-jhipster-and-neo4j-774639e9693

37 An OSS group eﬀort across companies • Team Drivers at Neo4j • Shoutout to Zhen and Nigel (@technige) • Spring Data Team at VMWare • Special thanks to Mark (@mp911de) • Spring Boot Team at VMWare • Special thanks to Stéphane (@snicoll) • And also to • Sergei (@bsideup) at VMWare • Frederik (@atomfrede) (JHipster)

38 Available now • Works with Neo4j 3.4+ • Reactive database access needs 4.0 • Multi-database feature needs Neo4j Enterprise Edition • Works with Neo4j Aura https://neo4j.com/aura/ • Provides Neo4j support in JHipster https://www.jhipster.tech • Coordinates: • Driver starter: https://github.com/neo4j/sdn-rx • SDN/RX: https://github.com/neo4j/sdn-rx

39 What to chose for a new project? • Used already by customers • 1.0.0 released in April • Will eventually replace SDN+OGM • Good choice for new projects • When it moves back under Spring Coordinates, packages will change • More eﬀort to migrate existing SDN+OGM code • Diﬀerent packages • More opinionated behaviour

Introducing Neo4j SDN⚡️RX

Introducing Neo4j SDN⚡️RX

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