Cant get only groups:
20: Sending: {"params": {}, "jsonrpc": "2.0", "method": "hostgroup.get", "auth": "", "id": 1}
10: Response Body: {u'jsonrpc': u'2.0', u'result': [

{u'groupid': u'1'}

,

{u'groupid': u'2'}

,

{u'groupid': u'4'}

,

{u'groupid': u'5'}

,

{u'groupid': u'6'}

], u'id': 1}
20: Sending: {"params": {"options":

{"groups": ["1", "2", "4", "5", "6"]}

, "format": "xml"}, "jsonrpc": "2.0", "method": "configuration.export", "auth": "", "id": 2}
10: Response Body:

{u'jsonrpc': u'2.0', u'result': u'<?xml version="1.0" encoding="UTF-8"?>\n<zabbix_export><version>2.0</version><date>2012-07-18T12:55:52Z</date></zabbix_export>\n', u'id': 2}