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Introduction to Spring Data Neo4j
Michael Hunger
1Donnerstag, 27. Oktober 2011
Me & You ?
๏Me: Michael Hunger, Neo Technology
• passionate software developer / Neo4j German Division
• Spring Data Neo4j Project Lead
•Neo4j Cloud Hosting
•michael.hunger@neotechnology.com / @mesirii
๏You:
•NOSQL ?
• Enterprise ?
•Rich Domain ?
( I just assume Java + Spring)
2Donnerstag, 27. Oktober 2011
What‘s up?
๏NOSQL overview
๏Spring Data overview
๏Networks are everywhere
๏Graph Databases
๏Neo4j introduction
๏Spring Data Neo4j introduction
3
3Donnerstag, 27. Oktober 2011
NOSQL overview
4
4Donnerstag, 27. Oktober 2011
What does NOSQL stand for?
5Donnerstag, 27. Oktober 2011
What does NOSQL stand for?
It’s not “No to SQL”
5Donnerstag, 27. Oktober 2011
What does NOSQL stand for?
It’s not “No to SQL”
It’s not “Never SQL”
5Donnerstag, 27. Oktober 2011
What does NOSQL stand for?
It’s not “No to SQL”
It’s not “Never SQL”
It’s “Not Only SQL”
5Donnerstag, 27. Oktober 2011
What does NOSQL stand for?
It’s not “No to SQL”
It’s not “Never SQL”
It’s “Not Only SQL”
NOSQL \no-seek-wool\ n. Describes ongoing trend where developers increasingly opt for non-relational databases to help solve their problems, in an effort to use the right tool for the right job.
5Donnerstag, 27. Oktober 2011
Why NOSQL now?
๏Trend 1: Size of data is growing
๏Trend 2: Data is increasingly connected
๏Trend 3: Data is increasingly semi-structured
๏Trend 4: Change in architecture
We have observed four trends:
6Donnerstag, 27. Oktober 2011
NOSQL categories
We see four main categories in the NOSQL space:•KVDynamo
•Column-familyBigTableDynamo-inspired
•DocumentLotus Notes
•GraphEuler & graph theoryConnections in brain
7Donnerstag, 27. Oktober 2011
NOSQL categories
We see four main categories in the NOSQL space:
•Redis
•Riak
•Voldemort
Key-Value
•KVDynamo
•Column-familyBigTableDynamo-inspired
•DocumentLotus Notes
•GraphEuler & graph theoryConnections in brain
7Donnerstag, 27. Oktober 2011
NOSQL categories
We see four main categories in the NOSQL space:
•Cassandra
•HBase
Column-family/BigTable
•Redis
•Riak
•Voldemort
Key-Value
•KVDynamo
•Column-familyBigTableDynamo-inspired
•DocumentLotus Notes
•GraphEuler & graph theoryConnections in brain
7Donnerstag, 27. Oktober 2011
NOSQL categories
We see four main categories in the NOSQL space:
•Cassandra
•HBase
Column-family/BigTable
•Redis
•Riak
•Voldemort
Key-Value
•MongoDB
•CouchDB
Document
•KVDynamo
•Column-familyBigTableDynamo-inspired
•DocumentLotus Notes
•GraphEuler & graph theoryConnections in brain
7Donnerstag, 27. Oktober 2011
NOSQL categories
We see four main categories in the NOSQL space:
•Cassandra
•HBase
Column-family/BigTable
•Redis
•Riak
•Voldemort
Key-Value
•MongoDB
•CouchDB
Document
•Neo4j
•InfiniteGraph
•OrientDB
•DEX
Graph
•KVDynamo
•Column-familyBigTableDynamo-inspired
•DocumentLotus Notes
•GraphEuler & graph theoryConnections in brain
7Donnerstag, 27. Oktober 2011
Scaling to size vs. Scaling to complexity
8
Size
Complexity
Key-Value stores
Bigtable clones
Document databases
Graph databases
8Donnerstag, 27. Oktober 2011
Scaling to size vs. Scaling to complexity
8
Size
Complexity
Key-Value stores
Bigtable clones
Document databases
Graph databases
Billions of nodesand relationships
8Donnerstag, 27. Oktober 2011
Scaling to size vs. Scaling to complexity
8
Size
Complexity
Key-Value stores
Bigtable clones
Document databases
Graph databases
> 90% of use cases
Billions of nodesand relationships
8Donnerstag, 27. Oktober 2011
Spring Data overview
9Donnerstag, 27. Oktober 2011
What is Spring Data
10
๏VMWare/SpringSource initiative to give Spring developers easy access to the emerging world of NOSQL, including:
•Non-relational databases
•MapReduce
•Grails NOSQL support
•Cross-store persistence
•Object Persistence Mapping Infrastructure
•Generic Repository Infrastructure
• upcoming Spring Roo add-ons
10Donnerstag, 27. Oktober 2011
Spring Data projects
๏Code is in SpringSource git repository:
• http://springsource.org/spring-data
• https://github.com/SpringSource/spring-data-*
๏ Includes:
• data-commons
• spring-data-graph-neo4j
• spring-data-{redis,riak}
• spring-data-mongo
• spring-data-jdbc
• spring-data-jpa
11Donnerstag, 27. Oktober 2011
Spring Data Neo4j
๏Focus on Spring Data Neo4j
๏VMWare is collaborating with Neo Technology, the company behind the Neo4j graph database.
๏Improved programming model: Annotation-based programming model for graph applications
๏Cross-store persistence: Extend existing JPA application with NOSQL persistence
๏Spring Roo support: Add graph persistence with Roo add-on
12Donnerstag, 27. Oktober 2011
13
Graphs are everywhere
13Donnerstag, 27. Oktober 2011
Even in the Matrix- everything is a grpah
14
Google Image Search: „graph OR network“
14Donnerstag, 27. Oktober 2011
Graphs Everywhere
๏Relationships in
• Politics, Economics, History, Science, Transportation
๏Biology, Chemistry, Physics, Sociology
•Body, Ecosphere, Reaction, Interactions
๏ Internet
•Hardware, Software, Interaction
๏Social Networks
• Family, Friends
•Work, Communities
•Neighbours, Cities, Society 15
15Donnerstag, 27. Oktober 2011
Good Relationships
๏the world is rich, messy and related data
๏relationships are as least as important as the things they connect
๏Graphs = Whole > Sum of all parts
๏complex interactions
๏always changing, change of structures as well
๏Graph: Relationships are part of the data
๏RDBMS: Relationships part of the fixed schema
16
16Donnerstag, 27. Oktober 2011
Questions and Answers
๏Complex Questions
๏Answers lie between the lines (things)
๏Locality of the information
๏Global searches / operations very expensive
๏constant query time, regardless of data volume
17
17Donnerstag, 27. Oktober 2011
Categories ?
๏Categories == Classes, Trees ?
๏What if more than one category fits?
๏Tags
๏Categories vi relationships like „IS_A“
๏any number, easy change
๏„virtual“ Relationships - Traversals
๏Category dynamically derived from queries
18
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Fowler & Christakis „Connected“
19
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New York Times R&D „Cascade“
20
20Donnerstag, 27. Oktober 2011
Deb Roy - MIT & Bluefin Labs
21
„Birth of a Word“ TED Talk
Researches Social Reactions to (Media) Events
21Donnerstag, 27. Oktober 2011
Neo4j introduction
22Donnerstag, 27. Oktober 2011
What is Neo4j?data model
23Donnerstag, 27. Oktober 2011
What is Neo4j?
A Graph Databasedata model
23Donnerstag, 27. Oktober 2011
What is Neo4j?
A Graph Databasedata model
23Donnerstag, 27. Oktober 2011
What is Neo4j?
A Graph Databasedata model
23Donnerstag, 27. Oktober 2011
What is Neo4j?
Node Node
A Graph Databasedata model
23Donnerstag, 27. Oktober 2011
What is Neo4j?
Node Node
A Graph Database
Typed relationship
data model
23Donnerstag, 27. Oktober 2011
What is Neo4j?
NodeNode
A Graph Database
Typed relationship
data model
key: value key: value
23Donnerstag, 27. Oktober 2011
For example
24Donnerstag, 27. Oktober 2011
For example
name: Oliver
24Donnerstag, 27. Oktober 2011
For example
name: Oliver name: Michael
24Donnerstag, 27. Oktober 2011
For example
name: Oliver name: MichaelWORKS_WITHproject: spring-data
24Donnerstag, 27. Oktober 2011
For example
name: Oliver name: MichaelWORKS_WITHproject: spring-data
company: VMware
EMPLOYED_BY
city: Dresdencountry: DE
LIVE
S_IN
24Donnerstag, 27. Oktober 2011
For example
name: Oliver name: MichaelWORKS_WITHproject: spring-data
company: VMware
EMPLOYED_BY
city: Dresdencountry: DE
LIVE
S_IN
name: Rod
KNOWS KNOWS
24Donnerstag, 27. Oktober 2011
For example
name: Oliver name: MichaelWORKS_WITHproject: spring-data
company: VMware
EMPLOYED_BY
city: Dresdencountry: DE
LIVE
S_IN
name: Rod
KNOWS KNOWS
food: Chinese
LIKE
S
24Donnerstag, 27. Oktober 2011
Best NOSQL Database for Spring ?Why ? Explain !
•Written in Java •Embeddable or standalone Server•Schema-free - perfect for rich domains•Fully transactional (ACID)•Persistent to custom on-disk file structure•Traversal speeds of 1,000+ hops per ms•24/7 production since 2003•Integrated indexing•Plenthora of language bindings
25Donnerstag, 27. Oktober 2011
Whiteboard friendly
26Donnerstag, 27. Oktober 2011
Whiteboard friendly
Allison
Ally’sBlog
OWNS
26Donnerstag, 27. Oktober 2011
Whiteboard friendly
Allison
Ally’sBlog
BlogPost
BlogPost 2
OWNS
WRO
TE
WROTE
BELONGS_TO
BELONGS_TO
26Donnerstag, 27. Oktober 2011
Whiteboard friendly
Allison
Ally’sBlog
BlogPost
BlogPost 2
Comment
Comment
OWNS
WRO
TE
WROTE
BELONGS_TO
BELONGS_TO
COMMENT_FORCO
MM
ENT_
FOR
26Donnerstag, 27. Oktober 2011
Whiteboard friendly
Allison
Ally’sBlog
BlogPost
BlogPost 2
Comment
Comment
OWNS
WRO
TE
WROTE
BELONGS_TO
BELONGS_TO
COMMENT_FORCO
MM
ENT_
FOR
26Donnerstag, 27. Oktober 2011
Show me some code, please
Node david = graphDb.createNode();Node andreas = graphDb.createNode();
david.setProperty(“name”, “David Montag”);andreas.setProperty(“name”, “Andreas Kollegger”);
Relationship presentedWith = david.createRelationshipTo( andreas, PresentationTypes.PRESENTED_WITH);presentedWith.setProperty(“date”, System.currentTimeMillis());
GraphDatabaseService graphDb = new EmbeddedGraphDatabase(“var/neo4j”);
27Donnerstag, 27. Oktober 2011
Show me some code, please
Node david = graphDb.createNode();Node andreas = graphDb.createNode();
david.setProperty(“name”, “David Montag”);andreas.setProperty(“name”, “Andreas Kollegger”);
Relationship presentedWith = david.createRelationshipTo( andreas, PresentationTypes.PRESENTED_WITH);presentedWith.setProperty(“date”, System.currentTimeMillis());
Transaction tx = graphDb.beginTx();try {
tx.success();} finally { tx.finish();}
GraphDatabaseService graphDb = new EmbeddedGraphDatabase(“var/neo4j”);
27Donnerstag, 27. Oktober 2011
Traversal framework
28Donnerstag, 27. Oktober 2011
Traversal frameworkExample: a dependency graph
A
BDC
28Donnerstag, 27. Oktober 2011
Traversal frameworkExample: a dependency graph
A
BDC
Query: Find all dependencies of A, transitively
28Donnerstag, 27. Oktober 2011
Traversal frameworkExample: a dependency graph
A
BDC
Query: Find all dependencies of A, transitively
28Donnerstag, 27. Oktober 2011
Traversal frameworkExample: a dependency graph
A
BDC
Query: Find all dependencies of A, transitively
28Donnerstag, 27. Oktober 2011
Traversal frameworkExample: a dependency graph
A
BDC
Query: Find all dependencies of A, transitively
28Donnerstag, 27. Oktober 2011
Traversal frameworkExample: a dependency graph
A
BDC
Query: Find all dependencies of A, transitively
TraversalDescription desc = Traversal.description() .relationships(ExampleTypes.DEPENDS_ON, Direction.OUTGOING);
Node a = ...;
for (Node dependency : desc.traverse(a).nodes()) { print(dependency);}
28Donnerstag, 27. Oktober 2011
So how do I find a node to traverse from?
?
29Donnerstag, 27. Oktober 2011
So how do I find a node to traverse from?
?By us
ing in
dexin
g!
29Donnerstag, 27. Oktober 2011
So how do I find a node to traverse from?
?name: DavidBy us
ing in
dexin
g!
29Donnerstag, 27. Oktober 2011
So how do I find a node to traverse from?
?Davidname: DavidBy
using
inde
xing!
29Donnerstag, 27. Oktober 2011
So how do I find a node to traverse from?
?Davidname: David
Ed
Allison
Michael
Andreas
By us
ing in
dexin
g!
29Donnerstag, 27. Oktober 2011
Cypher Query Language
๏Declarative query language
•Describe what you want, not how
•Based on pattern matching
๏Examples:
30
START david=node:people(name=”David M”) # index lookupMATCH david-[:knows]-()-[:knows]-foafWHERE foaf.age > 18RETURN foaf
START user=node(5, 15, 26, 28) # node IDsMATCH user--friendRETURN user, COUNT(friend), SUM(friend.money)
30Donnerstag, 27. Oktober 2011
Cypher Query Language
๏Declarative query language
•Describe what you want, not how
•Based on pattern matching
๏Examples:
30
START david=node:people(name=”David M”) # index lookupMATCH david-[:knows]-()-[:knows]-foafWHERE foaf.age > 18RETURN foaf
START user=node(5, 15, 26, 28) # node IDsMATCH user--friendRETURN user, COUNT(friend), SUM(friend.money)
(Experimental)
30Donnerstag, 27. Oktober 2011
Beyond basics๏Graph algorithm library
•Cheapest path (Dijkstra, A*)
• Shortest path
• Simple paths
•All paths
๏REST API access to Neo4j Standalone Server
๏High availability and online backups
• Provides fault tolerance and horizontal scaling of reads
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Spring Data Neo4j
32Donnerstag, 27. Oktober 2011
Spring Framework Conveniences
๏default enterprise development framework
๏ future Java Cloud stack
๏POJO centric application design
๏made AspectJ aspects socially acceptable (tx-config, @Configurable)
๏Template programming model
๏ Inversion of Control / Dependency Injection
๏Spring Java Config, configuration XML-namespaces
๏ lots of powerful libraries and library abstractions
๏existing, well-known persistence framework for JDBC
๏Spring Data project
33Donnerstag, 27. Oktober 2011
Programming model overview
๏SDN is the brain child of Rod Johnson and Emil Eifrém
•Wrote functional initial prototype
•Developed by Neo Technology and SpringSource teams
๏Uses annotations to define POJO entities
๏Entity state backed by graph database
๏Two modes of Object Graph Mapping
• Spring Data Mapping
• seamless object mapping leverages AspectJ
๏Spring Roo add-on available
34Donnerstag, 27. Oktober 2011
Spring Data Neo4j features
๏ Annotation-based programming model
๏ Spring Data Commons Repository support
๏ Neo4j Query (Cypher, Gremlin) and Traversal support
• on dynamic fields and via repository methods
๏ Neo4j indexing support (includes fulltext and numeric range queries)
๏ Entity types stored in the graph database as well
๏ Dynamic type projection (duck typing)
๏ Cross-store support for partial JPA / graph entities
๏ Support for JSR-303 (bean validation)
๏ Support for the Neo4j Server (remote server and in server extension)
๏ Neo4jTemplate with exception translation, optional transaction management and more
35
35Donnerstag, 27. Oktober 2011
public class Actor { private final Node underlyingNode;
Actor( final Node node ) { underlyingNode = node; }
public Node getUnderlyingNode() { return underlyingNode; }
public final String getName() { return (String) underlyingNode.getProperty( “name” ); }
public void setName( final String name ) { underlyingNode.setProperty( “name”, name ); }}
Classic Neo4j domain class
36Donnerstag, 27. Oktober 2011
Spring Data Neo4j domain class@NodeEntitypublic class Actor {
@Indexed private String name;
public String getName() { return name; }
public void setName(String name) { this.name = name; }}
37Donnerstag, 27. Oktober 2011
What about relationships
public Iterable<Movie> getMovies() { final List<Movie> movies = new LinkedList<Movie>(); for ( Relationship rel : underlyingNode.getRelationships( RelTypes.ACTS_IN, Direction.OUTGOING ) ) { movies.add( new Movie( rel.getEndNode() ) ); } return movies; }
@NodeEntityclass Actor { ...
Old @RelatedTo(type="ACTS_IN", elementCl
ass = Movie.class)
private Set<Movie> movies; public Iterable<Movie> getMovies() {
return movies; }
New
38Donnerstag, 27. Oktober 2011
Defining entity classes
39Donnerstag, 27. Oktober 2011
Defining entity classes
•@NodeEntity
• Represents a node in the graph
• Fields saved as properties on node
• References stored as relationships between nodes
• Instantiated using Java ‘new’ keyword, like any POJO
• Also returned by lookup mechanisms
• Type information stored in the graph
39Donnerstag, 27. Oktober 2011
Defining entity classes
40Donnerstag, 27. Oktober 2011
Defining entity classes
•@RelationshipEntity
• Represents a relationship in the graph
• Fields saved as properties on relationship
• Special fields for start- and end-nodes
• Only returned by lookup methods
40Donnerstag, 27. Oktober 2011
Fields in node entities (@NodeEntity)
• Primitive types and strings are directly persisted
• For all other types, Spring conversion support can be used
• Enum and Date conversion is provided out-of-the-box
•Transient fields not persisted
41
@NodeEntitypublic class Actor { private String name; private int age; private HairColor hairColor; private transient String nickname;}
41Donnerstag, 27. Oktober 2011
Fields in node entities (@NodeEntity)
• Fields of types that represent a node (@NodeEntity)
42
42Donnerstag, 27. Oktober 2011
Fields in node entities (@NodeEntity)
• Fields of types that represent a node (@NodeEntity)
42
@NodeEntitypublic class Movie {}
@NodeEntitypublic class Person { private Movie favoriteMovie;}
42Donnerstag, 27. Oktober 2011
Fields in node entities (@NodeEntity)
• Fields of types that represent a node (@NodeEntity)
42
@NodeEntitypublic class Movie {}
@NodeEntitypublic class Person { private Movie favoriteMovie;}
@NodeEntitypublic class Movie { private Actor topActor;}
@NodeEntitypublic class Actor { // Mirrors topActor in Movie @RelatedTo(type = ”topActor”, direction = Direction.INCOMING) private Movie wasTopActorIn;}
42Donnerstag, 27. Oktober 2011
Fields in node entities (@NodeEntity)
• Fields of collections of node entities: @RelatedTo
43
@NodeEntitypublic class Movie {}
@NodeEntitypublic class Actor { @RelatedTo(type = “ACTS_IN”) private Set<Movie> movies;}
43Donnerstag, 27. Oktober 2011
Fields in node entities (@NodeEntity)
๏Fields of collections of relationship entities: @RelatedToVia
๏Read only view of relationship entities44
@RelationshipEntitypublic class Role { @StartNode private Actor actor; @EndNode private Movie movie; private String roleName;}
@NodeEntitypublic class Actor { @RelatedToVia(type = “ACTS_IN”) private Iterable<Role> roles;}
44Donnerstag, 27. Oktober 2011
Fields in relationship entities (@RelationshipEntity)
• Primitive and convertible types work just the same
• @StartNode and @EndNode provide access to the start and end node entities for the relationship entity
@RelationshipEntitypublic class Role { @StartNode private Actor actor; @EndNode private Movie movie; private String title;}
45Donnerstag, 27. Oktober 2011
Indexing
@NodeEntitypublic class Actor { @Indexed private String name; @Indexed private HairColor hairColor;
GraphRepository<Actor> actorRepo = template.repositoryFor(Actor.class);Actor kevin = actorRepo.findByPropertyValue(“name”, “Kevin Bacon”);Iterable<Actor> allBlondActors = actorRepo.findAllByPropertyValue(“hairColor”, “blond”);
It can then be looked up:
By annotating an entity field with @Indexed it becomes searchable:
46Donnerstag, 27. Oktober 2011
Indexing
@NodeEntitypublic class Actor { @Indexed(type = FULLTEXT) private String name;
๏ Index name defaults to domain class name
๏ Index key defaults to field name
๏Fulltext and spatial index types
๏Repository query methods for any Lucene query, including ranges:
Iterable<Actor> allKevinsOlderThan32 = actorRepo.findAllByQuery(“name:Kevin* AND age>32”);Iterable<Actor> youngActors = actorRepo.findAllByRange(“age”, 3, 18);
47Donnerstag, 27. Oktober 2011
Traversal
48
@NodeEntitypublic class Actor { @GraphTraversal( traversalBuilder = CoactorsTraversalDescriptionBuilder.class) private Iterable<Actor> coactors;}
public class CoactorsTraversalDescriptionBuilder implements FieldTraversalDescriptionBuilder { public TraversalDescription build(...) { return Traversal.description() .evaluator(Evaluators.atDepth(2)) .relationships(RelTypes.ACTS_IN); }}
Example for dynamic field computation
48Donnerstag, 27. Oktober 2011
Cypher query language
49
@NodeEntitypublic class Actor { @Query(“START actor=({self}) ” + “MATCH (actor)-[:ACTS_IN]->(movie)<-[:ACTS_IN]-(coactor) ” + “RETURN coactor”) private Iterable<Actor> coactors;}
@NodeEntitypublic class Actor { @Query(“START actor=({self}) ” + “MATCH (actor)-[:ACTS_IN]->(movie)<-[:ACTS_IN]-(coactor) ” + “RETURN movie.title, coactor.name”) private Iterable<Map<String, Object>> movieCoactorPairs;}
49Donnerstag, 27. Oktober 2011
Spring-Data-Mapping
50
๏Based on Spring-Data-Commons infrastructure
• Extract Mapping Meta Information
‣Neo4jPersistentEntity, Neo4jPersistentProperty
• Entity-Converter Implementations for Object-Graph-Mapping
‣Type-resolution
‣Entity construction
‣Transfer properties
‣loaed for eagerly fetched relationships
•Neo4j-Template for Graph-Interaction
50Donnerstag, 27. Oktober 2011
AspectJ
51
๏ Introduces interface to entities:
•NodeBacked into @NodeEntity classes
• RelationshipBacked into @RelationshipEntity classes
๏NodeBacked introduces methods such as:
• relateTo
• findByQuery
• findAllByTraversal
• ...
๏going to be pulled out in separate Active-Record-Mixin
51Donnerstag, 27. Oktober 2011
AspectJ - Tooling
52
๏ IDE‘s
• latest versions of STS / Eclipse with current AJDT plugin
• IntelliJ IDEA 10.5 compile + run, some editor quirks
‣full AspectJ support in IDEA 11
๏Build Systems
•Maven
•Gradle
•Ant / Ivy
• ...
52Donnerstag, 27. Oktober 2011
AspectJ - NodeBacked.relateTo
53
<T extends RelationshipBacked> T NodeBacked.relateTo( NodeBacked node, Class<T> relationshipEntityType, String relationshipType);
@NodeEntitypublic class Actor { public Role actsIn(Movie movie, String roleName) { Role role = relateTo(movie, Role.class, “ACTS_IN”); role.setName(roleName); return role; }}
usage:
53Donnerstag, 27. Oktober 2011
Interface based Repositories๏ based on Repository infrastructure in Spring Data Commons
๏ just define the interface and the namespace configuration
๏provide out-of-the-box support for
•CRUD-Operations
• Index-Lookups
•Traversal-Execution
•Graph-Queries (Cypher, Gremlin)
• derived Queries
• Spatial Queries
๏extensible via custom methods with provided implementations54
54Donnerstag, 27. Oktober 2011
Repositories
55
interface MovieRepository extends GraphRepository<Movie> { Movie findById(String id); Page<Movie> findByTitle(String title, Pageable page);}
<neo4j:repositories base-package=“com.example.repositories„/
@Controllerpublic class MovieController { @Autowired MovieRepository moviesRepository;
@RequestMapping(value = "/movies/{movieId}",...) public String show(Model model, @PathVariable String movieId) { Movie movie = moviesRepository.findByPropertyValue("id", movieId); Movie movie = moviesRepository.findById(movieId); model.addAttribute("movie", movie); return "/movies/show"; }}
55Donnerstag, 27. Oktober 2011
Other repository query methods
Iterable<Actor> allActors = actorRepo.findAll();
long numberOfActors = actorRepo.count();
Actor jeffGoldblum = actorRepo.findOne(42);
boolean actorExists = actorRepo.exists(42);
Iterable<Actor> actors = actorRepo.findAllByTraversal(movie,traversal);
Page<Actor> actors = actorRepo.findAll(new PageRequest(page, PAGE_SIZE));
Iterable<Actor> actorsByNameAndAge = actorRepo.findAll(new Sort(„name“,“age“));
56Donnerstag, 27. Oktober 2011
Repository-Query-Support
57
interface MovieRepository extends GraphRepository<Movie> {
@Query("start m=({movie}) match m-[ACTS_IN]-actor return actor") Iterable<Actor> getActorsCypher(@Param("movie") Movie m); @Query("start movie =({0}) match (movie)<-[role:ACTS_IN]-(actor) return actor.name, role.title") Iterable<Map<String,Object>> getCast(Movie m);
@Query(value = "g.v(movie).out('ACTS_IN')", type = QueryType.Gremlin) Iterable<Person> getActorsGremlin(@Param("movie") Movie m);}
57Donnerstag, 27. Oktober 2011
Neo4j-Template (I)
๏well known Spring Template Pattern
๏Resource / Transaction Management
๏Convenience Methods
๏Nodes and Entities handling & conversion
๏Fluent Query Result Handling
๏Works also via REST with Neo4j-Server
๏Exception Translation
58
58Donnerstag, 27. Oktober 2011
Neo4j-Template (II)
59
template.lookup("node", "name", "David") .to(String.class, new PropertyContainerNameConverter()).single()
template.traverse(node, traversal) .to(Integer.class,new ResultConverter<Path,Integer>() { public Integer convert(Path path, Class<String> type) { return path.length(); }})
template.query("start movie=(Movies,title, {m}) match movie-->actor return actor", map("m","Matrix")).to(Actor.class)
template.execute("g.v(ref).outE", map("ref",0)).to(Relationship.class)
59Donnerstag, 27. Oktober 2011
REST-Client-Support
60
<bean id="restGraphDatabaseService" class="org.sf.data.neo4j.rest.SpringRestGraphDatabase"> <constructor-arg value="http://localhost:7473/db/data" /> </bean>
<datagraph:config graphDatabaseService="restGraphDatabaseService"/>
๏drop-in replacement for the embedded GraphDatabase
๏works transparently with POJO-Entity-Mapping and
Neo4j-Template
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REST-Server-Support
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public class HelloWorldInitializer extends SpringPluginInitializer { public HelloWorldInitializer() { super(new String[]{"spring/helloWorldServer-Context.xml"}, Pair.of("worldRepository", WorldRepository.class), Pair.of("graphRepositoryFactory", GraphRepositoryFactory.class)); }}
๏ integrate Spring Data Neo4j config with already running
Graph-Database in Neo4j-Server
๏expose Spring Beans as Jersey Injectables
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Cross-store persistence
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A scenario...
You have a traditional web app using JPA to persist data to a relational database
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Option C: Introducing cross-store persistence
๏ JPA data and NOSQL data can share a data model
๏Could be the entire entity, or some fields of an entity
๏We call this cross-store persistence
•One transaction manager to coordinate the NOSQL database with the JPA relational database
•AspectJ support to manage the NOSQL entities and fields
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The JPA data model
Restaurant@Entitypublic class Restaurant {
@Id @GeneratedValue private Long id; private String name; private String city; private String state; private String zipCode;
UserAccount@Entity@Table(name = "user_account")public class UserAccount { @Id @GeneratedValue private Long id; private String userName; private String firstName; private String lastName; @Temporal(TemporalType.TIMESTAMP) private Date birthDate; @ManyToMany(cascade = CascadeType.ALL) private Set<Restaurant> favorites;
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Adding to the data model
Recommendation
@RelationshipEntitypublic class Recommendation { @StartNode private UserAccount user; @EndNode private Restaurant restaurant; private int stars; private String comment;
Restaurant@Entity@NodeEntity(partial = true)public class Restaurant { @Id @GeneratedValue private Long id; private String name; private String city; private String state; private String zipCode;
UserAccount@Entity@Table(name = "user_account")@NodeEntity(partial = true)public class UserAccount { @Id @GeneratedValue private Long id; private String userName; private String firstName; private String lastName; @Temporal(TemporalType.TIMESTAMP) private Date birthDate; @ManyToMany(cascade = CascadeType.ALL) private Set<Restaurant> favorites;
@GraphProperty String nickname; @RelatedTo(type = "friends", elementClass = UserAccount.class) Set<UserAccount> friends; @RelatedToVia(type = "recommends", elementClass = Recommendation.class) Iterable<Recommendation> recommendations;
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Adding to the data model
Recommendation
@RelationshipEntitypublic class Recommendation { @StartNode private UserAccount user; @EndNode private Restaurant restaurant; private int stars; private String comment;
Restaurant@Entity@NodeEntity(partial = true)public class Restaurant { @Id @GeneratedValue private Long id; private String name; private String city; private String state; private String zipCode;
UserAccount@Entity@Table(name = "user_account")@NodeEntity(partial = true)public class UserAccount { @Id @GeneratedValue private Long id; private String userName; private String firstName; private String lastName; @Temporal(TemporalType.TIMESTAMP) private Date birthDate; @ManyToMany(cascade = CascadeType.ALL) private Set<Restaurant> favorites;
@GraphProperty String nickname; @RelatedTo(type = "friends", elementClass = UserAccount.class) Set<UserAccount> friends; @RelatedToVia(type = "recommends", elementClass = Recommendation.class) Iterable<Recommendation> recommendations;
66Donnerstag, 27. Oktober 2011
Adding to the data model
Recommendation
@RelationshipEntitypublic class Recommendation { @StartNode private UserAccount user; @EndNode private Restaurant restaurant; private int stars; private String comment;
Restaurant@Entity@NodeEntity(partial = true)public class Restaurant { @Id @GeneratedValue private Long id; private String name; private String city; private String state; private String zipCode;
UserAccount@Entity@Table(name = "user_account")@NodeEntity(partial = true)public class UserAccount { @Id @GeneratedValue private Long id; private String userName; private String firstName; private String lastName; @Temporal(TemporalType.TIMESTAMP) private Date birthDate; @ManyToMany(cascade = CascadeType.ALL) private Set<Restaurant> favorites;
@GraphProperty String nickname; @RelatedTo(type = "friends", elementClass = UserAccount.class) Set<UserAccount> friends; @RelatedToVia(type = "recommends", elementClass = Recommendation.class) Iterable<Recommendation> recommendations;
66Donnerstag, 27. Oktober 2011
Adding to the data model
Recommendation
@RelationshipEntitypublic class Recommendation { @StartNode private UserAccount user; @EndNode private Restaurant restaurant; private int stars; private String comment;
Restaurant@Entity@NodeEntity(partial = true)public class Restaurant { @Id @GeneratedValue private Long id; private String name; private String city; private String state; private String zipCode;
UserAccount@Entity@Table(name = "user_account")@NodeEntity(partial = true)public class UserAccount { @Id @GeneratedValue private Long id; private String userName; private String firstName; private String lastName; @Temporal(TemporalType.TIMESTAMP) private Date birthDate; @ManyToMany(cascade = CascadeType.ALL) private Set<Restaurant> favorites;
@GraphProperty String nickname; @RelatedTo(type = "friends", elementClass = UserAccount.class) Set<UserAccount> friends; @RelatedToVia(type = "recommends", elementClass = Recommendation.class) Iterable<Recommendation> recommendations;
66Donnerstag, 27. Oktober 2011
Adding to the data model
Recommendation
@RelationshipEntitypublic class Recommendation { @StartNode private UserAccount user; @EndNode private Restaurant restaurant; private int stars; private String comment;
Restaurant@Entity@NodeEntity(partial = true)public class Restaurant { @Id @GeneratedValue private Long id; private String name; private String city; private String state; private String zipCode;
UserAccount@Entity@Table(name = "user_account")@NodeEntity(partial = true)public class UserAccount { @Id @GeneratedValue private Long id; private String userName; private String firstName; private String lastName; @Temporal(TemporalType.TIMESTAMP) private Date birthDate; @ManyToMany(cascade = CascadeType.ALL) private Set<Restaurant> favorites;
@GraphProperty String nickname; @RelatedTo(type = "friends", elementClass = UserAccount.class) Set<UserAccount> friends; @RelatedToVia(type = "recommends", elementClass = Recommendation.class) Iterable<Recommendation> recommendations;
66Donnerstag, 27. Oktober 2011
Spring Data Neo4j Roo add-on
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๏Roo adding support for non-JPA persistence providers
๏Spring Data Neo4j was the first NOSQL persistence Roo Add-On
๏See the chapter on Spring Data Neo4j in the latest O’Reilly Roo book, Getting Started with Roo.
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Spring Data Neo4j Roo add-on
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roo> project --topLevelPackage org.neo4j.imdbroo> graph setup --provider NEO4J --databaseLocation target/imdb
roo> graph entity --class ~.model.Movieroo> field string titleroo> field number --fieldName year --type java.lang.Integer --permitReservedWords --primitive
roo> graph entity --class ~.model.Actorroo> field string name
roo> graph relationship --to Movie --from Actor --fieldName movies --type ACTS_IN --cardinality ONE_TO_MANYroo> graph relationship --via ~.model.Role --to Movie --from Actor --fieldName roles --type ACTS_IN --cardinality ONE_TO_MANYroo> graph relationship --from Movie --to Actor --type ACTS_IN --fieldName actors --direction INCOMING --cardinality MANY_TO_ONEroo> field string --fieldName title --class ~.model.Role
roo> controller scaffold --class ~.web.ActorController --entity ~.model.Actorroo> controller scaffold --class ~.web.MovieController --entity ~.model.Movie
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Spring Data Neo4j Guidebook“Good Relationships”
๏Spring Data Neo4j comes with a great Guide Book, featuring:
• Forewords by Rod Johnson and Emil Eifrem
•An easy to read, narrative tutorial walkthrough for cineasts.net
•A comprehensive reference for all the details
•Check it out here: http://spring.neo4j.org/guide
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“I’m excited about Spring Data Neo4j.... Spring Data Neo4j makes working with Neo4j amazingly easy, and therefore has the potential to make you more successful as a developer.”
Rod Johnson, founder of Spring
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The end (and the beginning!)๏See the Spring Data Neo4j site for more info:
http://spring.neo4j.org
๏Check out the developer notes at GitHub:http://spring.neo4j.org/notes
๏Again, don’t miss our fantastic e-book on Spring Data Neo4j:http://spring.neo4j.org/guide
๏Spring Data Forum at http://spring.neo4j.org/discussions
๏All about Neo4j: http://neo4j.org
๏Neo4j videos and webinars: http://video.neo4j.org
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Cineasts.net
Check Out: http://spring.neo4j.org/tutorial71Donnerstag, 27. Oktober 2011
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