This Heroku Demo uses the

Spark Java Web Framework by Per Wendel @perwendel.

And the Neo4j Graph Database Heroku Add-On via the Java Rest Bindings.

The Demo can be found at http://spark-neo4j.heroku.com

Code is quote simple:

public class Main {

    private static final String LAST_HELLO = "lastHello";

    public static void main(String[] args) {
        final GraphDatabaseService gdb = new RestGraphDatabase(getenv("NEO4J_REST_URL"), getenv("NEO4J_LOGIN"), getenv("NEO4J_PASSWORD"));
        setPort(Integer.parseInt(getenv("PORT")));
        get(new Route("/") {
            public Object handle(Request request, Response response) {
                gdb.getReferenceNode().setProperty(LAST_HELLO,System.currentTimeMillis());
                response.type("text/html");
                return "Hello World! <a href='/neo'>Neo4j Reference Node</a>";
            }
        });
        get(new Route("/neo") {
            public Object handle(Request request, Response response) {
                final Node node = gdb.getReferenceNode();
                final Date lastHello = new Date((Long) node.getProperty(LAST_HELLO, 0L));
                return "Hello World from the Neo4j-Node id "+ node.getId()+" last hello "+ lastHello;
            }
        });
    }
}