neo4j(4)Java Sample/Scala Client and Routing

neo4j(4)Java Sample/Scala Client and Routing

1. Java Sample
Here is the dependencies for neo4j-java in pom.xml
<dependencies>   

  <dependency>            

    <groupId>commons-logging</groupId>            

    <artifactId>commons-logging</artifactId>            

    <version>1.1.3</version>   

  </dependency>   

  <dependency>         

    <groupId>org.neo4j</groupId>         

    <artifactId>neo4j</artifactId>         

    <version>2.1.3</version>   

  </dependency>   

  <dependency>         

    <groupId>log4j</groupId>         

    <artifactId>log4j</artifactId>         

    <version>1.2.17</version>     

  </dependency>

</dependencies>

RailroadExample.java

package com.sillycat.easyhbase.app;

import java.util.Iterator;

import org.neo4j.graphalgo.GraphAlgoFactory;
import org.neo4j.graphalgo.PathFinder;
import org.neo4j.graphalgo.WeightedPath;
import org.neo4j.graphdb.Direction;
import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Path;
import org.neo4j.graphdb.PathExpanders;
import org.neo4j.graphdb.Relationship;
import org.neo4j.graphdb.Transaction;
import org.neo4j.graphdb.factory.GraphDatabaseFactory;
import org.neo4j.graphdb.index.Index;

import com.sillycat.easyhbase.util.GraphUtil;
import com.sillycat.easyhbase.util.RelTypes;

public class RailroadExample {

     private static String DB_PATH = "/tmp/neo4j";
     
     public static void main(final String[] args) {
          GraphDatabaseService graphDb = new GraphDatabaseFactory().newEmbeddedDatabase(DB_PATH);
          GraphUtil.registerShutdownHook(graphDb);
 
          Transaction tx = graphDb.beginTx();
          try {
               Index<Node> nodeIndex = graphDb.index().forNodes("nodes");
              
               Node londonNode = graphDb.createNode();
               //create node London
               londonNode.setProperty("name", "London");
               //add name into index
               nodeIndex.add(londonNode, "name", "London");
 
               //Brighton
               Node brightonNode = graphDb.createNode();
               brightonNode.setProperty("name", "Brighton");
               nodeIndex.add(brightonNode, "name", "Brighton");
 
               //Portsmouth
               Node portsmouthNode = graphDb.createNode();
               portsmouthNode.setProperty("name", "Portsmouth");
               nodeIndex.add(portsmouthNode, "name", "Portsmouth");
 
               //Bristol
               Node bristolNode = graphDb.createNode();
               bristolNode.setProperty("name", "Bristol");
               nodeIndex.add(bristolNode, "name", "Bristol");
 
               //Oxford
               Node oxfordNode = graphDb.createNode();
               oxfordNode.setProperty("name", "Oxford");
               nodeIndex.add(oxfordNode, "name", "Oxford");
 
               //Gloucester
               Node gloucesterNode = graphDb.createNode();
               gloucesterNode.setProperty("name", "Gloucester");
               nodeIndex.add(gloucesterNode, "name", "Gloucester");
 
               //Northampton
               Node northamptonNode = graphDb.createNode();
               northamptonNode.setProperty("name", "Northampton");
               nodeIndex.add(northamptonNode, "name", "Northampton");
 
               //Southampton
               Node southamptonNode = graphDb.createNode();
               southamptonNode.setProperty("name", "Southampton");
               nodeIndex.add(southamptonNode, "name", "Southampton");
 
               // london -> brighton ~ 52mi
               Relationship r1 = londonNode.createRelationshipTo(brightonNode,
                         RelTypes.LEADS_TO);
               //relationship gets property distance
               r1.setProperty("distance", 52);
 
               // brighton -> portsmouth ~ 49mi
               Relationship r2 = brightonNode.createRelationshipTo(portsmouthNode,
                         RelTypes.LEADS_TO);
               r2.setProperty("distance", 49);
 
               // portsmouth -> southampton ~ 20mi
               Relationship r3 = portsmouthNode.createRelationshipTo(
                         southamptonNode, RelTypes.LEADS_TO);
               r3.setProperty("distance", 20);
 
               // london -> oxford ~95mi
               Relationship r4 = londonNode.createRelationshipTo(oxfordNode,
                         RelTypes.LEADS_TO);
               r4.setProperty("distance", 95);
 
               // oxford -> southampton ~66mi
               Relationship r5 = oxfordNode.createRelationshipTo(southamptonNode,
                         RelTypes.LEADS_TO);
               r5.setProperty("distance", 66);
 
               // oxford -> northampton ~45mi
               Relationship r6 = oxfordNode.createRelationshipTo(northamptonNode,
                         RelTypes.LEADS_TO);
               r6.setProperty("distance", 45);
 
               // northampton -> bristol ~114mi
               Relationship r7 = northamptonNode.createRelationshipTo(bristolNode,
                         RelTypes.LEADS_TO);
               r7.setProperty("distance", 114);
 
               // southampton -> bristol ~77mi
               Relationship r8 = southamptonNode.createRelationshipTo(bristolNode,
                         RelTypes.LEADS_TO);
               r8.setProperty("distance", 77);
 
               // northampton -> gloucester ~106mi
               Relationship r9 = northamptonNode.createRelationshipTo(
                         gloucesterNode, RelTypes.LEADS_TO);
               r9.setProperty("distance", 106);
 
               // gloucester -> bristol ~35mi
               Relationship r10 = gloucesterNode.createRelationshipTo(bristolNode,
                         RelTypes.LEADS_TO);
               r10.setProperty("distance", 35);
 
               tx.success();
 
               System.out.println("searching for the shortest route from London to Bristol..");
               PathFinder<WeightedPath> finder = GraphAlgoFactory.dijkstra(
                         PathExpanders.forTypeAndDirection(RelTypes.LEADS_TO,Direction.OUTGOING), "distance");
 
               WeightedPath path = finder.findSinglePath(londonNode, bristolNode);
               System.out.println("London - Bristol with a distance of: " + path.weight() + " and via: ");
               for (Node n : path.nodes()) {
                    System.out.print(" " + n.getProperty("name"));
               }
              
               System.out.println();
               System.out.println();
              
               System.out.println("searching for all routes from London to southamptonNode..");
               PathFinder<Path> finderAll = GraphAlgoFactory.allPaths(
                         PathExpanders.forTypeAndDirection(RelTypes.LEADS_TO,Direction.OUTGOING), Integer.MAX_VALUE);
              
               Iterable<Path> allPaths = finderAll.findAllPaths(londonNode, southamptonNode);
               Iterator<Path> it = allPaths.iterator();
               while(it.hasNext()){
                    Path tmp_path = (Path) it.next();
                    System.out.println("Path is as follow: ");
                    int distance = 0;
                    for (Node n : tmp_path.nodes()) {
                         System.out.print(" " + n.getProperty("name"));
                         distance = distance + (Integer)n.getRelationships(RelTypes.LEADS_TO, Direction.OUTGOING).iterator().next().getProperty("distance");
                    }
                    System.out.println(" with distance:" + distance);
               }
 
 
          } finally {
               tx.close();;
               graphDb.shutdown();
          }
     }
    
}

Some other Util Classes
package com.sillycat.easyhbase.util; import org.neo4j.graphdb.RelationshipType; publicenum RelTypes implements RelationshipType {      KNOWS, LEADS_TO }



package com.sillycat.easyhbase.util;

import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Relationship;
import org.neo4j.graphdb.index.Index;
import org.neo4j.tooling.GlobalGraphOperations;

public class GraphUtil {

     public static void cleanUp(final GraphDatabaseService graphDb,
               final Index<Node> nodeIndex) {
          for (Node node : GlobalGraphOperations.at(graphDb).getAllNodes()) {
               for (Relationship rel : node.getRelationships()) {
                    rel.delete();
                    //delete all relationship
               }
               //remove all nodes from index
               nodeIndex.remove(node);
               //remote node itself
               node.delete();
          }
 
     }
 
     public static void registerShutdownHook(final GraphDatabaseService graphDb) {
          Runtime.getRuntime().addShutdownHook(new Thread() {
               @Override
               public void run() {
                    graphDb.shutdown();
               }
          });
     }
    
}

It works great. But I do not plan to run neo4j in embedded mode, so I will work to check for other clients.


References:
https://github.com/AnormCypher/AnormCypher

http://www.hascode.com/2012/01/neo4j-graph-database-tutorial-how-to-build-a-route-planner-and-other-examples/
http://jason691353279.iteye.com/blog/2056339

http://docs.neo4j.org.cn/tutorials-java-embedded-traversal.html