public static AGGraphMaker getMarker(String repository_id) {
        try {
            AGCatalog catalog = server.getCatalog(CATALOG_ID);

            AGRepository repository;
            if (catalog.hasRepository(repository_id)) {
                repository = catalog.openRepository(repository_id);
            } else {
                repository = catalog.createRepository(repository_id);
                repository.initialize();
            }

            AGRepositoryConnection conn = repository.getConnection();
            AGGraphMaker marker = new AGGraphMaker(conn);
            return marker;
        } catch (RepositoryException e) {
            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        } catch (OpenRDFException e) {
            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        }

        return null;
    }