public String getPastUpdate() {
		String past_update = (String) cache.get("past_update");
		if (past_update != null)
			return past_update;
		Entity past_entity = null;
		DatastoreService datastore = DatastoreServiceFactory
				.getDatastoreService();
		try {
			past_entity = datastore.get(KeyFactory.createKey("past_string",
					"onlyOne"));
		} catch (EntityNotFoundException e) {
		}
		past_update = (String) past_entity.getProperty("past_update");
		return past_update;
	}