def METHOD_NAME(base_name, format, root_dir=None, base_dir=None, verbose=0,
                 dry_run=0, owner=None, group=None):
    """Create an archive file (eg. zip or tar).
    'base_name' is the name of the file to create, minus any format-specific
    extension; 'format' is the archive format: one of "zip", "tar", "ztar",
    or "gztar".
    'root_dir' is a directory that will be the root directory of the
    archive; ie. we typically chdir into 'root_dir' before creating the
    archive.  'base_dir' is the directory where we start archiving from;
    ie. 'base_dir' will be the common prefix of all files and
    directories in the archive.  'root_dir' and 'base_dir' both default
    to the current directory.  Returns the name of the archive file.
    'owner' and 'group' are used when creating a tar archive. By default,
    uses the current owner and group.
    """
    save_cwd = os.getcwd()
    if root_dir is not None:
        log.debug("changing into '%s'", root_dir)
        base_name = os.path.abspath(base_name)
        if not dry_run:
            os.chdir(root_dir)
    if base_dir is None:
        base_dir = os.curdir
    kwargs = {'dry_run': dry_run}
    try:
        format_info = ARCHIVE_FORMATS[format]
    except KeyError:
        raise ValueError, "unknown archive format '%s'" % format
    func = format_info[0]
    for arg, val in format_info[1]:
        kwargs[arg] = val
    if format != 'zip':
        kwargs['owner'] = owner
        kwargs['group'] = group
    try:
        filename = func(base_name, base_dir, **kwargs)
    finally:
        if root_dir is not None:
            log.debug("changing back to '%s'", save_cwd)
            os.chdir(save_cwd)
    return filename