@Override
 public boolean open() {
   BaseConfiguration conf = new BaseConfiguration();
   conf.setProperty("storage.backend", storageBackend);
   conf.setProperty("storage.tablename", storageTableName);
   titanGraph = TitanFactory.open(conf);
   titanGraph.makeKey(vertexUserId).dataType(String.class).indexed(Vertex.class).make();
   titanGraph.makeLabel(edgeMentions).make();
   titanGraph.makeLabel(edgeReTweets).make();
   titanGraph.commit();
   return true;
 }