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spring-data-neo4j/developer_notes.html
Johannes Mockenhaupt b86149785c Documentation updates. 
* SDG->SDN renames.
* Couple of typos fixed.
* URL fixes.
* Update AspectJ section on Eclipse IDE integration.
2012-07-29 14:34:43 +02:00

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<title>Spring Data Neo4j - Developer Notes</title>
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<h1 style="text-align: center">Developer Notes</h1>
<div style="padding:1em;">
<img src="http://neo4j.org/wp-content/uploads/2011/09/springdataNeo4j-logo-cmyk-11.png" alt="Spring Data Neo4j Logo"/>
</div>
<div class="note">
<h3>Neo4j - [IS_A] -> Property Graph</h3>
<p><strong>Nodes</strong> with key-value properties are connected by <strong>typed</strong>, directed <strong>relationships</strong> with properties.</p>
<em>TODO put in a pretty picture</em>
<h4>Cypher is a query language:</h4>
<pre>
start movie=(id) match movie<-[:ACTS_IN]-actor
where actor.age > 20 return movie, actor.name
order by movie.title </pre>
<h4>Traversals walk the graph in the prescribed way</h4>
<pre>
TraversalDescription actors = Traversal.description()
.relationships("ACTS_IN").filter(returnAllButStartNode());
for (Node actor : actors.traverse(movie))
...</pre>
<h4>Transactional: TX needed for write operations</h4>
<pre>
Transaction tx=graphDatabaseService.beginTx();
try {
... graph operations ...
tx.success();
} catch(Exception e) {
tx.failure();
} finally {
tx.finish();
}
</pre>
</div>
<div class="note">
<h3> Maven Dependency</h3>
<pre>
&lt;dependency>
&lt;groupId>org.springframework.data&lt;/groupId>
&lt;artifactId>spring-data-neo4j[-aspects]&lt;/artifactId>
&lt;version>2.0.0.RC1&lt;/version>
&lt;/dependency>
</pre>
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<div class="note">
<h3>Spring-Config</h3>
<pre>&lt;beans ...
xmlns:neo4j="http://www.swf.org/schema/data/neo4j"
xsi:schemaLocation=
"http://www.sfw.org/schema/data/neo4j" ...>
...
&lt;neo4j:config store-dir="graph.db"/>
&lt;neo4j:repositories base-package="com.example.repositories"/>
...
&lt;/beans></pre>
<h4>Testing</h4>
<pre>&lt;neo4j:config graphDatabaseService="gds"/>
&lt;bean id="gds" class="...ImpermanentGraphDatabase"/></pre>
<h4>REST</h4>
<pre>&lt;neo4j:config graphDatabaseService="rds"/>
&lt;bean id="rds" class="...SpringRestGraphDatabase"/></pre>
</div>
<div class="note">
<h3>Entity - Annotations</h3>
<ul>
<li><code>@NodeEntity</code> marks a domain class as backed by a node in the graph</li>
<li><code>@RelationshipEntity</code> marks a domain class as backed by a relationship in the graph</li>
<li><code>@GraphId</code> Field for id</li>
<li><code>@Indexed([fulltext=true],[indexName=name])</code> Auto-Indexing</li>
<li><code>@RelatedTo([direction=Direction], [type=TYPE])</code> define type and direction of relationship on <code>Entity, Iterable&lt;E>, Set&lt;E></code> fields</li>
<li><code>@RelatedToVia([direction=Direction], [type=TYPE])</code> like <code>@RelatedTo,</code> but targets Relationship-Entities</li>
<li><code>@Query(query, [type=QueryType])</code> computed field, executes graph query in Cypher or Gremlin</li>
<li><code>@GraphTraversal(traversal=~TraversalBuilder.class, [elementClass=Person.class])</code> computed field, executes traversal starting from entity-node</li>
</ul>
</div>
<div class="note">
<h3>Example</h3>
<pre>
@NodeEntity
public class Movie {
@GraphId Long id;
@Indexed(fulltext = true, indexName = "search")
String title;
Person director;
@RelatedTo(type="ACTS_IN", direction = INCOMING)
Set&lt;Person> actors;
@RelatedToVia(type = "RATED")
Iterable&lt;Rating> ratings;
@Query("start movie=node({self}) match
movie-->genre&lt;--similar return similar")
Iterable&lt;Movie> similarMovies;
}</pre>
</div>
<div class="note">
<h3>Repositories</h3>
<pre>
interface MovieRepository extends GraphRepository&lt;Movie> {
@Query("start movie={0} match m&lt;-[rating:RATED]-user
return rating")
Iterable&lt;Rating> getRatings(Movie movie);
// Co-Actors
Iterable&lt;Person> findByActorsMoviesActorName(name)
}
&lt;neo4j:repositories base-package="com.example.dao"/></pre>
<ul>
<li>Provide CRUD, Finder, Query and Traversal abilities by default.</li>
<li>Automatic Finders can be derived from method names (like (G)Rails) or @Query annotations.</li>
<li>custom method implementations possible</li>
</ul>
</div>
<div class="note">
<h3>Neo4jTemplate</h3>
<ul><li>convenience methods for graph operations, transaction and exception handling</li>
<li>index lookups, cypher and gremlin queries, traversal execution with fluent result converter API</li>
<li>preconfigured and customizable conversion of results to a variety of types</li></ul>
</div>
<div class="note">
<h3>AspectJ - ActiveRecordMixin</h3>
adds the following methods, when implementing the NodeBacked interface
<pre>
getPersistentState()
relateTo(target, ...),
getRelationshipTo(...)
persist(),
remove(),
detach()
...</pre>
</div>
<div class="note">
<h3>Roo Add-on</h3>
<pre>
roo> addon search graph
roo> addon install id --searchResultId 01
roo> project --topLevelPackage net.cineasts
roo> graph setup --provider NEO4J --databaseLocation cineasts
roo> graph entity --class ~.model.Movie
roo> field string title
roo> graph entity --class ~.model.Actor
roo> field string name
roo> graph relationship --to Movie --from Actor
--fieldName movies --type ACTS_IN --cardinality ONE_TO_MANY
roo> controller all --package ~.web</pre>
</div>
<div class="note">
<h3>Libraries</h3>
<h4>spring-data-neo4j</h4>
Provides Repository based Object <-> Graph Mapping that copies data from and to the graph database.
<h4>spring-data-neo4j-aspects</h4>
Provides transparent property and relationship mapping inside of transactions with live read- and write-through to the graph database.
<h4>spring-data-neo4j-cross-store</h4>
Allows to partially store properties and relationships of JPA entities in the graph database.
<h4>spring-data-neo4j-rest</h4>
Provides transparent remote access to Neo4j-Server via its REST Api (uses <code>org.neo4j:neo4j-rest-graphdb</code>)
</div>
<div class="note">
<h3>AspectJ - STS / eclipse setup</h3>
<ul>
<li>STS 2.7.1</li>
<li>import existing maven project or set aspectj nature</li>
<li>Project Properties -> AspectJ -> Aspect Paths</li>
<li>AspectJ Configurator installed</li>
<li>sometimes build after restart required</li></ul>
</div>
<div class="note">
<h3>Links</h3>
<ul style="list-style: none">
<li><a href="http://neo4j.org">http://neo4j.org</a></li>
<li><a href="http://spring-neo4j.org/">http://spring-neo4j.org/</a></li>
<li><a href="http://spring-neo4j.org/guide">http://spring-neo4j.org/guide</a></li>
<li><a href="http://spring-neo4j.org/discussions">http://spring-neo4j.org/discussions</a></li>
<li><a href="http://spring-neo4j.org/docs">http://spring-neo4j.org/docs</a></li>
<li><a href="http://spring-neo4j.org/download">http://spring-neo4j.org/download</a></li>
<li><a href="http://spring-neo4j.org/issues">http://spring-neo4j.org/issues</a></li>
<li><a href="http://spring-neo4j.org/source">http://spring-neo4j.org/source</a></li>
<li><a href="http://cineats.net">http://cineasts.net</a></li>
</ul>
</div>
<div style="background-color: white;display: inline-block;">
<a href="http://spring.neo4j.org" target="_blank"><img width="200" height="200" src="http://spring.neo4j.org/qr"/></a>
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