def get_active_topics(host=TASR_HOST, port=TASR_PORT, timeout=TIMEOUT):
    ''' GET /tasr/active_topics
    Retrieves available metadata for active topics (i.e. -- groups) with
    registered schemas.  A dict of <topic name>:<topic metadata> is returned.
    '''
    url = 'http://%s:%s/tasr/active_topics' % (host, port)
    resp = requests.get(url, timeout=timeout)
    if resp == None:
        raise TASRError('Timeout for request to %s' % url)
    if not 200 == resp.status_code:
        raise TASRError('Failed request to %s (status code: %s)' %
                        (url, resp.status_code))
    topic_metas = SubjectHeaderBot.extract_metadata(resp)
    return topic_metas