Group items tagged

Semantic Content Management

"Example - the MATRIX The Graph As mentioned before, Social Networks represent just a tiny fraction of the applications of graph databases, but they are easy to understand for this example. To demonstrate the basic functionality of Neo4j, below is a small graph from the Matrix movie, visualized with the Eclipse RCP based Neoclipse for Neo4j: The graph is connected to a known reference node (id=0) for convenience in order to find the way into the network from a known starting point. This is not necessary, but has proven very usable in practice. The Java implementation looks something like this: Create a new graph database in folder "target/neo" EmbeddedGraphDatabase graphdb = new EmbeddedGraphDatabase("target/neo"); Relationship types can be created on-the-fly: RelationshipType KNOWS = DynamicRelationshipType.withName("KNOWS"); or via typesafe Java Enum: enum Relationships implements RelationshipType { KNOWS, INLOVE, HAS_CODED, MATRIX } Now, create two nodes and attach a "name" property to each of them. Then, connect these nodes witha KNOWS relationship: Node neo = graphdb.createNode(); node.setProperty("name", "Neo"); Node morpheus = graphdb.createNode(); morpheus.setProperty("name", "Morpheus"); neo.createRelationshipTo(morpheus, KNOWS); Any operation modifying the graph or needing isolation levels for data is wrapped in a transaction, so rollback and recovery work out of the box: Transaction tx = graphdb.beginTx(); try { Node neo = graphdb.createNode(); ... tx.success(); } catch (Exception e) { tx.failure(); } finally { tx.finish(); } The full code to create the Matrix graph the looks something like this: graphdb = new EmbeddedGraphDatabase("target/neo4j"); index = new LuceneIndexService(graphdb); Transaction tx = graphdb.beginTx(); try { Node root = graphdb.getReferenceNode(); // we connect Neo with the root node, to gain an entry point to the graph // not neccessary but practical. neo = createAndConnectNode("Neo", root, MATRIX); Node mo