GraphDatabase - Titan with AWS DynamoDB

Query and Output 1

#A simple Gremlin query that finds restaurants based on a type of cuisine is shown below:

gremlin> g.V.has('genreId', 'Pizzeria').in.restaurant_name

==>La Fontana Pizza Restaurante and Cafe
==>Dominos Pizza
==>Little Cesarz
==>pizza clasica
==>Restaurante Tiberius

Query and Output 2

# A simple recommendation system
g.V.has('userId','U1101').out('friend').outE('visit').has('visit_food', T.gte, 1).as('x').inV.as('y').out('restaurant_genre').has('genreId', 'Seafood').back('x').transform{e, m -> [food: m.x.visit_food, name:m.y.restaurant_name]}.groupCount{it.name}.cap

==>{Restaurante y Pescaderia Tampico=1, Restaurante Marisco Sam=1, Mariscos El Pescador=2}

RestaurantFactory.java

package com.equb.aws;

import java.io.InputStreamReader;
import java.net.URL;
import java.util.Iterator;

import com.thinkaurelius.titan.core.Multiplicity;
import com.thinkaurelius.titan.core.PropertyKey;
import com.thinkaurelius.titan.core.TitanGraph;
import com.thinkaurelius.titan.core.TitanVertex;
import com.thinkaurelius.titan.core.attribute.Geoshape;
import com.thinkaurelius.titan.core.schema.TitanManagement;
import com.tinkerpop.blueprints.Edge;
import com.tinkerpop.blueprints.Vertex;

public class RestaurantFactory {

	public static final String RESTAURANT_ID = "RestaurantId";
	public static final String USER_ID = "userId";
	public static final String GENRE = "genreId";

	public static final String PROP_RESTAURANT_NAME = "restaurant_name";
	public static final String PROP_VISIT_RATING = "visit_rating";
	public static final String PROP_VISIT_FOOD = "visit_food";
	
	public static void load(final TitanGraph graph) throws Exception {

		// set up the structure of our graph
		TitanManagement mgmt = graph.getManagementSystem();

		if (mgmt.getGraphIndex(RESTAURANT_ID) == null) {
			final PropertyKey RESTAURANTIdKey = mgmt.makePropertyKey(RESTAURANT_ID).dataType(Integer.class).make();
			mgmt.buildIndex(RESTAURANT_ID, Vertex.class).addKey(RESTAURANTIdKey).unique().buildCompositeIndex();
			mgmt.makePropertyKey(PROP_RESTAURANT_NAME).dataType(String.class).make();
		}

		if (mgmt.getGraphIndex(USER_ID) == null) {
			final PropertyKey userKey = mgmt.makePropertyKey(USER_ID).dataType(String.class).make();
			mgmt.buildIndex(USER_ID, Vertex.class).addKey(userKey).unique().buildCompositeIndex();
		}

		if (mgmt.getGraphIndex(GENRE) == null) {
			final PropertyKey genreKey = mgmt.makePropertyKey(GENRE).dataType(String.class).make();
			mgmt.buildIndex(GENRE, Vertex.class).addKey(genreKey).unique().buildCompositeIndex();
		}

		mgmt.makeVertexLabel("restaurant").make();
		mgmt.makeVertexLabel("genre").make();
		mgmt.makeVertexLabel("user").make();

		mgmt.makeEdgeLabel("visit").multiplicity(Multiplicity.MULTI).make();
		mgmt.makePropertyKey(PROP_VISIT_RATING).dataType(Integer.class).make();
		mgmt.makePropertyKey(PROP_VISIT_FOOD).dataType(Integer.class).make();

		mgmt.makeEdgeLabel("restaurant_genre").multiplicity(Multiplicity.MULTI).make();
		mgmt.makeEdgeLabel("friend").multiplicity(Multiplicity.MULTI).make();

		mgmt.commit();

		// load the restaurants

        TitanVertex vertex = graph.addVertexWithLabel("restaurant");
        vertex.addProperty(RESTAURANT_ID, nextLine[0]);
        vertex.addProperty(PROP_RESTAURANT_NAME, nextLine[1]);

		// load the genres (types of cuisine)
        TitanVertex vertex = graph.addVertexWithLabel("genre");
        vertex.addProperty(GENRE, nextLine[0]);

		// load the customers (users)
        TitanVertex vertex = graph.addVertexWithLabel("user");
        vertex.addProperty(USER_ID, nextLine[0]);

		// load some visits (from user to restaurant)
        Vertex userVertex = get(graph, USER_ID, nextLine[0]);
        Vertex RestaurantVertex = get(graph, RESTAURANT_ID, nextLine[1]);

        Edge visitEdge = userVertex.addEdge("visit", RestaurantVertex);

        visitEdge.setProperty(PROP_VISIT_RATING, nextLine[2]);
        visitEdge.setProperty(PROP_VISIT_FOOD, nextLine[3]);

		// load the genre for each restaurant
        Vertex RESTAURANTVertex = get(graph, RESTAURANT_ID, nextLine[0]);
        Vertex genreVertex = get(graph, GENRE, nextLine[1]);

        if (RESTAURANTVertex != null && genreVertex != null) {
            RESTAURANTVertex.addEdge("restaurant_genre", genreVertex);
        }

		// load the friends
		Vertex userVertex = get(graph, USER_ID, nextLine[0]);
        Vertex friendVertex = get(graph, USER_ID, nextLine[2]);

        if (userVertex != null && friendVertex != null) {
            userVertex.addEdge("friend", friendVertex);
        }
    }

	// helper function to get a vertex based on a property
	private static Vertex get(TitanGraph graph, String key, String value) {
		Iterator<Vertex> it = graph.getVertices(key, value).iterator();
		Vertex vertex = null;
		if (it.hasNext()) {
			vertex = it.next();
		}
		return vertex;

	}
}