vnc_cfg_ifmap.py

#
# Copyright (c) 2013 Juniper Networks, Inc. All rights reserved.
#

"""
Layer that transforms VNC config objects to ifmap representation
"""
from cfgm_common.zkclient import ZookeeperClient, IndexAllocator
from gevent import ssl, monkey
monkey.patch_all()
import gevent
import gevent.event
from gevent.queue import Queue, Empty
import sys
import time
from pprint import pformat

from lxml import etree, objectify
import cgitb
import StringIO
import re

import socket
from netaddr import IPNetwork

from cfgm_common import ignore_exceptions, utils
from cfgm_common.ifmap.client import client, namespaces
from cfgm_common.ifmap.request import NewSessionRequest, PublishRequest
from cfgm_common.ifmap.id import Identity
from cfgm_common.ifmap.operations import PublishUpdateOperation,\
    PublishDeleteOperation
from cfgm_common.ifmap.response import Response, newSessionResult
from cfgm_common.ifmap.metadata import Metadata
from cfgm_common.exceptions import ResourceExhaustionError, ResourceExistsError
from cfgm_common.vnc_cassandra import VncCassandraClient
from cfgm_common.vnc_kombu import VncKombuClient

import copy
import json
import uuid
import datetime
import pycassa
import pycassa.util
import pycassa.cassandra.ttypes
from pycassa.system_manager import *
from datetime import datetime
from pycassa.util import *

import signal, os


#from cfgm_common import vnc_type_conv
from provision_defaults import *
import cfgm_common.imid
from cfgm_common.exceptions import *
from vnc_quota import *
from gen.vnc_ifmap_client_gen import *
from gen.vnc_cassandra_client_gen import *
from pysandesh.connection_info import ConnectionState
from pysandesh.gen_py.process_info.ttypes import ConnectionStatus, \
    ConnectionType
from pysandesh.gen_py.sandesh.ttypes import SandeshLevel

from sandesh.traces.ttypes import DBRequestTrace, MessageBusNotifyTrace, \
    IfmapTrace

import logging
logger = logging.getLogger(__name__)

@ignore_exceptions
def get_trace_id():
    try:
        req_id = gevent.getcurrent().trace_request_id
    except Exception:
        req_id = 'req-%s' %(str(uuid.uuid4()))
        gevent.getcurrent().trace_request_id = req_id

    return req_id
# end get_trace_id

@ignore_exceptions
def trace_msg(trace_obj, trace_name, sandesh_hdl, error_msg=None):
    if trace_obj:
        if error_msg:
            trace_obj.error = error_msg
        trace_obj.trace_msg(name=trace_name, sandesh=sandesh_hdl)
# end trace_msg

class VncIfmapClient(VncIfmapClientGen):

    def handler(self, signum, frame):
        file = open("/tmp/api-server-ifmap-cache.txt", "w")
        file.write(str(self._id_to_metas))
        file.close()

    def __init__(self, db_client_mgr, ifmap_srv_ip, ifmap_srv_port,
                 uname, passwd, ssl_options):
        super(VncIfmapClient, self).__init__()
        self._ifmap_srv_ip = ifmap_srv_ip
        self._ifmap_srv_port = ifmap_srv_port
        self._username = uname
        self._password = passwd
        self._ssl_options = ssl_options
        self._queue = Queue(100000)
        self._dequeue_greenlet = gevent.spawn(self._publish_to_ifmap_dequeue)
        self._CONTRAIL_XSD = "http://www.contrailsystems.com/vnc_cfg.xsd"
        self._IPERMS_NAME = "id-perms"
        self._IPERMS_FQ_NAME = "contrail:" + self._IPERMS_NAME
        self._SUBNETS_NAME = "contrail:subnets"
        self._IPAMS_NAME = "contrail:ipams"
        self._SG_RULE_NAME = "contrail:sg_rules"
        self._POLICY_ENTRY_NAME = "contrail:policy_entry"

        self._NAMESPACES = {
            'env':   "http://www.w3.org/2003/05/soap-envelope",
            'ifmap':   "http://www.trustedcomputinggroup.org/2010/IFMAP/2",
            'meta':
            "http://www.trustedcomputinggroup.org/2010/IFMAP-METADATA/2",
            'contrail':   self._CONTRAIL_XSD
        }

        self._db_client_mgr = db_client_mgr
        self._sandesh = db_client_mgr._sandesh

        ConnectionState.update(conn_type = ConnectionType.IFMAP,
            name = 'IfMap', status = ConnectionStatus.INIT, message = '',
            server_addrs = ["%s:%s" % (ifmap_srv_ip, ifmap_srv_port)])
        self._conn_state = ConnectionStatus.INIT

        self._reset_cache()

        # Set the signal handler
        signal.signal(signal.SIGUSR2, self.handler)

        # Initialize ifmap-id handler (alloc|convert|parse etc.)
        self._imid_handler = ImidGen()

        self._init_conn()
        self._publish_config_root()
    # end __init__

    def _init_conn(self):
        mapclient = client(("%s" % (self._ifmap_srv_ip),
                            "%s" % (self._ifmap_srv_port)),
                           self._username, self._password,
                           self._NAMESPACES, self._ssl_options)
        self._mapclient = mapclient

        connected = False
        while not connected:
            try:
                result = mapclient.call('newSession', NewSessionRequest())
                connected = True
            except socket.error as e:
                time.sleep(3)

        ConnectionState.update(conn_type = ConnectionType.IFMAP,
            name = 'IfMap', status = ConnectionStatus.UP, message = '',
            server_addrs = ["%s:%s" % (self._ifmap_srv_ip,
                                       self._ifmap_srv_port)])
        self._conn_state = ConnectionStatus.UP
        msg = 'IFMAP connection ESTABLISHED'
        self.config_log(msg, level=SandeshLevel.SYS_NOTICE)

        mapclient.set_session_id(newSessionResult(result).get_session_id())
        mapclient.set_publisher_id(newSessionResult(result).get_publisher_id())
    # end _init_conn

    def _reset_cache(self):
        # Cache of metas populated in ifmap server. Useful in update to find
        # what things to remove in ifmap server
        self._id_to_metas = {}
    # end _reset_cache


    def _publish_config_root(self):
        # config-root
        buf = cStringIO.StringIO()
        perms = Provision.defaults.perms['config-root']
        perms.exportChildren(buf, level=1, pretty_print=False)
        id_perms_xml = buf.getvalue()
        buf.close()
        update = {}
        meta = Metadata(self._IPERMS_NAME, '',
                        {'ifmap-cardinality': 'singleValue'},
                        ns_prefix='contrail', elements=id_perms_xml)
        self._update_id_self_meta(update, meta)
        self._publish_update("contrail:config-root:root", update)
    # end _publish_config_root

    def config_log(self, msg, level):
        self._db_client_mgr.config_log(msg, level)
    # end config_log

    @ignore_exceptions
    def _generate_ifmap_trace(self, oper, body):
        req_id = get_trace_id()
        ifmap_trace = IfmapTrace(request_id=req_id)
        ifmap_trace.operation = oper
        ifmap_trace.body = body

        return ifmap_trace
    # end _generate_ifmap_trace

    def _publish_to_ifmap_enqueue(self, oper, oper_body, do_trace=True):
        # safety check, if we proceed ifmap-server reports error
        # asking for update|delete in publish
        if not oper_body:
            return
        self._queue.put((oper, oper_body, do_trace))
    # end _publish_to_ifmap_enqueue

    def _publish_to_ifmap_dequeue(self):
        while self._queue.peek():
            publish_discovery = False
            request = ''
            traces = []
            while True:
                try:
                    (oper, oper_body, do_trace) = self._queue.get_nowait()
                    if oper == 'publish_discovery':
                        publish_discovery = True
                        break
                    if do_trace:
                        trace = self._generate_ifmap_trace(oper, oper_body)
                        traces.append(trace)
                    request += oper_body
                    if len(request) > 1024*1024:
                        break
                except Empty:
                    break
            ok = True
            if request:
                ok, msg = self._publish_to_ifmap(request)
            for trace in traces:
                if ok:
                    trace_msg(trace, 'IfmapTraceBuf', self._sandesh)
                else:
                    trace_msg(trace, 'IfmapTraceBuf', self._sandesh,
                              error_msg=msg)
            if publish_discovery and ok:
                self._db_client_mgr._api_svr_mgr.publish_ifmap_to_discovery()
    # end _publish_to_ifmap_dequeue

    def _publish_to_ifmap(self, oper_body):
        try:
            not_published = True
            retry_count = 0
            while not_published:
                sess_id = self._mapclient.get_session_id()
                req_xml = PublishRequest(sess_id, oper_body)
                resp_xml = self._mapclient.call('publish', req_xml)

                resp_doc = etree.parse(StringIO.StringIO(resp_xml))
                err_codes = resp_doc.xpath(
                    '/env:Envelope/env:Body/ifmap:response/errorResult/@errorCode',
                    namespaces=self._NAMESPACES)
                if err_codes:
                    if retry_count == 0:
                        log_str = 'Error publishing to ifmap, req: %s, resp: %s' \
                                  %(req_xml, resp_xml)
                        self.config_log(log_str, level=SandeshLevel.SYS_ERR)

                    retry_count = retry_count + 1
                    result = self._mapclient.call('newSession',
                                                  NewSessionRequest())
                    sess_id = newSessionResult(result).get_session_id()
                    pub_id = newSessionResult(result).get_publisher_id()
                    self._mapclient.set_session_id(sess_id)
                    self._mapclient.set_publisher_id(pub_id)
                else: # successful publish
                    not_published = False
                    break
            # end while not_published

            if retry_count:
                log_str = 'Success publishing to ifmap after %d tries' \
                          %(retry_count)
                self.config_log(log_str, level=SandeshLevel.SYS_ERR)

            return True, resp_xml
        except Exception as e:
            if (isinstance(e, socket.error) and
                self._conn_state != ConnectionStatus.DOWN):
                log_str = 'Connection to IFMAP down. Failed to publish %s' %(
                    oper_body)
                self.config_log(log_str, level=SandeshLevel.SYS_ERR)
                self._conn_state = ConnectionStatus.DOWN
                ConnectionState.update(
                    conn_type=ConnectionType.IFMAP,
                    name='IfMap', status=ConnectionStatus.DOWN, message='',
                    server_addrs=["%s:%s" % (self._ifmap_srv_ip,
                                             self._ifmap_srv_port)])

                self._reset_cache()
                self._db_client_mgr._api_svr_mgr.un_publish_ifmap_to_discovery()
                # this will block till connection is re-established
                self._init_conn()
                self._publish_config_root()
                self._db_client_mgr.db_resync()
                return False, log_str
            else:
                log_str = 'Failed to publish %s to ifmap: %s' %(oper_body,
                                                                str(e))
                self.config_log(log_str, level=SandeshLevel.SYS_ERR)
                return False, log_str
    # end _publish_to_ifmap

    def _build_request(self, id1_name, id2_name, meta_list, delete=False):
            request = ''
            id1 = unicode(Identity(name=id1_name, type="other",
                                   other_type="extended"))
            if id2_name != 'self':
                id2 = unicode(Identity(name=id2_name, type="other",
                                       other_type="extended"))
            else:
                id2 = None
            for m in meta_list:
                if delete:
                    filter = unicode(m) if m else None
                    op = PublishDeleteOperation(id1=id1, id2=id2,
                                                filter=filter)
                else:
                    op = PublishUpdateOperation(id1=id1, id2=id2,
                                                metadata=unicode(m),
                                                lifetime='forever')
                request += unicode(op)
            return request

    def _delete_id_self_meta(self, self_imid, meta_name):
        mapclient = self._mapclient

        del_str = self._build_request(self_imid, 'self', [meta_name], True)
        self._publish_to_ifmap_enqueue('delete', del_str)

        # del meta from cache and del id if this was last meta
        if meta_name:
            prop_name = meta_name.replace('contrail:', '')
            del self._id_to_metas[self_imid][prop_name]
            if not self._id_to_metas[self_imid]:
                del self._id_to_metas[self_imid]
        else:
            del self._id_to_metas[self_imid]
    # end _delete_id_self_meta

    def _delete_id_pair_meta_list(self, id1, meta_list):
        mapclient = self._mapclient
        del_str = ''
        for id2, metadata in meta_list:
            del_str += self._build_request(id1, id2, [metadata], True)

        self._publish_to_ifmap_enqueue('delete', del_str)

        # del meta,id2 from cache and del id if this was last meta
        def _id_to_metas_delete(id1, id2, meta_name):
            if id1 not in self._id_to_metas:
                return
            if meta_name not in self._id_to_metas[id1]:
                return
            if not self._id_to_metas[id1][meta_name]:
                del self._id_to_metas[id1][meta_name]
                if not self._id_to_metas[id1]:
                    del self._id_to_metas[id1]
                return

            # if meta is prop, noop
            if 'id' not in self._id_to_metas[id1][meta_name][0]:
                return
            self._id_to_metas[id1][meta_name] = [
                m for m in self._id_to_metas[id1][meta_name] if m['id'] != id2]
        for id2, metadata in meta_list:
            if metadata:
                meta_name = metadata.replace('contrail:', '')
                # replace with remaining refs
                _id_to_metas_delete(id1, id2, meta_name)
                _id_to_metas_delete(id2, id1, meta_name)
            else: # no meta specified remove all links from id1 to id2
                for meta_name in self._id_to_metas.get(id1, {}).keys():
                    _id_to_metas_delete(id1, id2, meta_name)
                for meta_name in self._id_to_metas.get(id2, {}).keys():
                    _id_to_metas_delete(id2, id1, meta_name)
    # end _delete_id_pair_meta_list

    def _delete_id_pair_meta(self, id1, id2, metadata):
        self._delete_id_pair_meta_list(id1, [(id2, metadata)])
    # end _delete_id_pair_meta

    def _update_id_self_meta(self, update, meta):
        """ update: dictionary of the type
                update[<id> | 'self'] = list(metadata)
        """
        mlist = update.setdefault('self', [])
        mlist.append(meta)
    # end _update_id_self_meta

    def _update_id_pair_meta(self, update, to_id, meta):
        mlist = update.setdefault(to_id, [])
        mlist.append(meta)
     # end _update_id_pair_meta

    def _publish_update(self, self_imid, update):
        if self_imid not in self._id_to_metas:
            self._id_to_metas[self_imid] = {}

        mapclient = self._mapclient
        requests = []
        for id2 in update:
            metalist = update[id2]
            requests.append(self._build_request(self_imid, id2, metalist))

            # remember what we wrote for diffing during next update
            for m in metalist:
                meta_name = m._Metadata__name.replace('contrail:', '')
                if id2 == 'self':
                    self._id_to_metas[self_imid][meta_name] = [{'meta':m}]
                    continue
                if meta_name in self._id_to_metas[self_imid]:
                    for id_meta in self._id_to_metas[self_imid][meta_name]:
                        if id_meta['id'] == id2:
                            id_meta['meta'] = m
                            break
                    else:
                        self._id_to_metas[self_imid][meta_name].append({'meta':m,
                                                                        'id': id2})
                else:
                   self._id_to_metas[self_imid][meta_name] = [{'meta':m,
                                                               'id': id2}]

                if id2 not in self._id_to_metas:
                    self._id_to_metas[id2] = {}
                if meta_name in self._id_to_metas[id2]:
                    for id_meta in self._id_to_metas[id2][meta_name]:
                        if id_meta['id'] == self_imid:
                            id_meta['meta'] = m
                            break
                    else:
                        self._id_to_metas[id2][meta_name].append({'meta':m,
                                                                  'id': self_imid})
                else:
                   self._id_to_metas[id2][meta_name] = [{'meta':m,
                                                         'id': self_imid}]
        upd_str = ''.join(requests)
        self._publish_to_ifmap_enqueue('update', upd_str)
    # end _publish_update

    def fq_name_to_ifmap_id(self, obj_type, fq_name):
        return cfgm_common.imid.get_ifmap_id_from_fq_name(obj_type, fq_name)
    # end fq_name_to_ifmap_id

    def ifmap_id_to_fq_name(self, ifmap_id):
        return cfgm_common.imid.get_fq_name_from_ifmap_id(ifmap_id)
    # end ifmap_id_to_fq_name

# end class VncIfmapClient


class VncServerCassandraClient(VncCassandraClient):
    # Useragent datastore keyspace + tables (used by neutron plugin currently)
    _USERAGENT_KEYSPACE_NAME = 'useragent'
    _USERAGENT_KV_CF_NAME = 'useragent_keyval_table'
    _MAX_COL = 10000000

    @classmethod
    def get_db_info(cls):
        db_info = VncCassandraClient.get_db_info() + \
                  [(cls._USERAGENT_KEYSPACE_NAME, [cls._USERAGENT_KV_CF_NAME])]
        return db_info
    # end get_db_info

    def __init__(self, db_client_mgr, cass_srv_list, reset_config, db_prefix):
        self._db_client_mgr = db_client_mgr
        keyspaces = {
            self._USERAGENT_KEYSPACE_NAME: [(self._USERAGENT_KV_CF_NAME, None)]
        }
        super(VncServerCassandraClient, self).__init__(
            cass_srv_list, reset_config, db_prefix,keyspaces, self.config_log,
            db_client_mgr.generate_url)
        self._useragent_kv_cf = self._cf_dict[self._USERAGENT_KV_CF_NAME]
    # end __init__

    def config_log(self, msg, level):
        self._db_client_mgr.config_log(msg, level)
    # end config_log

    def create(self, method_name, *args, **kwargs):
        method = getattr(self, '_cassandra_%s_create' % (method_name))
        return method(*args, **kwargs)
    # end create

    def read(self, method_name, *args, **kwargs):
        method = getattr(self, '_cassandra_%s_read' % (method_name))
        return method(*args, **kwargs)
    # end read

    def count_children(self, method_name, *args, **kwargs):
        method = getattr(self, '_cassandra_%s_count_children' % (method_name))
        return method(*args, **kwargs)
    # end read


    def update(self, method_name, *args, **kwargs):
        method = getattr(self, '_cassandra_%s_update' % (method_name))
        return method(*args, **kwargs)
    # end update

    def delete(self, method_name, *args, **kwargs):
        method = getattr(self, '_cassandra_%s_delete' % (method_name))
        return method(*args, **kwargs)
    # end delete

    def list(self, method_name, *args, **kwargs):
        method = getattr(self, '_cassandra_%s_list' % (method_name))
        return method(*args, **kwargs)
    # end list


    def ref_update(self, obj_type, obj_uuid, ref_type, ref_uuid, ref_data, operation):
        bch = self._obj_uuid_cf.batch()
        if operation == 'ADD':
            self._create_ref(bch, obj_type, obj_uuid, ref_type, ref_uuid, ref_data)
        elif operation == 'DELETE':
            self._delete_ref(bch, obj_type, obj_uuid, ref_type, ref_uuid)
        else:
            pass
        self.update_last_modified(bch, obj_uuid)
        bch.send()
    # end ref_update

    def _create_prop(self, bch, obj_uuid, prop_name, prop_val):
        bch.insert(obj_uuid, {'prop:%s' % (prop_name): json.dumps(prop_val)})
    # end _create_prop

    def _update_prop(self, bch, obj_uuid, prop_name, new_props):
        if new_props[prop_name] is None:
            bch.remove(obj_uuid, columns=['prop:' + prop_name])
        else:
            bch.insert(
                obj_uuid,
                {'prop:' + prop_name: json.dumps(new_props[prop_name])})

        # prop has been accounted for, remove so only new ones remain
        del new_props[prop_name]
    # end _update_prop

    def _create_child(self, bch, parent_type, parent_uuid,
                      child_type, child_uuid):
        child_col = {'children:%s:%s' %
                     (child_type, child_uuid): json.dumps(None)}
        bch.insert(parent_uuid, child_col)

        parent_col = {'parent:%s:%s' %
                      (parent_type, parent_uuid): json.dumps(None)}
        bch.insert(child_uuid, parent_col)
    # end _create_child

    def _delete_child(self, bch, parent_type, parent_uuid,
                      child_type, child_uuid):
        child_col = {'children:%s:%s' %
                     (child_type, child_uuid): json.dumps(None)}
        bch.remove(parent_uuid, columns=[
                   'children:%s:%s' % (child_type, child_uuid)])
    # end _delete_child

    def _create_ref(self, bch, obj_type, obj_uuid, ref_type,
                    ref_uuid, ref_data):
        bch.insert(
            obj_uuid, {'ref:%s:%s' %
                  (ref_type, ref_uuid): json.dumps(ref_data)})
        if obj_type == ref_type:
            bch.insert(
                ref_uuid, {'ref:%s:%s' %
                      (obj_type, obj_uuid): json.dumps(ref_data)})
        else:
            bch.insert(
                ref_uuid, {'backref:%s:%s' %
                      (obj_type, obj_uuid): json.dumps(ref_data)})
    # end _create_ref

    def _update_ref(self, bch, obj_type, obj_uuid, ref_type,
                    old_ref_uuid, new_ref_infos):
        if ref_type not in new_ref_infos:
            # update body didn't touch this type, nop
            return

        if old_ref_uuid not in new_ref_infos[ref_type]:
            # remove old ref
            bch.remove(obj_uuid, columns=[
                       'ref:%s:%s' % (ref_type, old_ref_uuid)])
            if obj_type == ref_type:
                bch.remove(old_ref_uuid, columns=[
                           'ref:%s:%s' % (obj_type, obj_uuid)])
            else:
                bch.remove(old_ref_uuid, columns=[
                           'backref:%s:%s' % (obj_type, obj_uuid)])
                self._db_client_mgr.dbe_cache_invalidate({'uuid':
                                                         old_ref_uuid})
        else:
            # retain old ref with new ref attr
            new_ref_data = new_ref_infos[ref_type][old_ref_uuid]
            bch.insert(
                obj_uuid,
                {'ref:%s:%s' %
                 (ref_type, old_ref_uuid): json.dumps(new_ref_data)})
            if obj_type == ref_type:
                bch.insert(
                    old_ref_uuid,
                    {'ref:%s:%s' %
                     (obj_type, obj_uuid): json.dumps(new_ref_data)})
            else:
                bch.insert(
                    old_ref_uuid,
                    {'backref:%s:%s' %
                     (obj_type, obj_uuid): json.dumps(new_ref_data)})
                self._db_client_mgr.dbe_cache_invalidate({'uuid':
                                                         old_ref_uuid})
            # uuid has been accounted for, remove so only new ones remain
            del new_ref_infos[ref_type][old_ref_uuid]
    # end _update_ref

    def _delete_ref(self, bch, obj_type, obj_uuid, ref_type, ref_uuid):
        send = False
        if bch is None:
            send = True
            bch = self._cassandra_db._obj_uuid_cf.batch()
        bch.remove(obj_uuid, columns=['ref:%s:%s' % (ref_type, ref_uuid)])
        if obj_type == ref_type:
            bch.remove(ref_uuid, columns=[
                       'ref:%s:%s' % (obj_type, obj_uuid)])
        else:
            bch.remove(ref_uuid, columns=[
                       'backref:%s:%s' % (obj_type, obj_uuid)])
        if send:
            bch.send()
    # end _delete_ref

    def is_latest(self, id, tstamp):
        id_perms_json = self._obj_uuid_cf.get(
            id, columns=['prop:id_perms'])['prop:id_perms']
        id_perms = json.loads(id_perms_json)
        if id_perms['last_modified'] == tstamp:
            return True
        else:
            return False
    # end is_latest

    def update_last_modified(self, bch, obj_uuid, id_perms=None):
        if id_perms is None:
            id_perms = json.loads(
                self._obj_uuid_cf.get(obj_uuid,
                                      ['prop:id_perms'])['prop:id_perms'])
        id_perms['last_modified'] = datetime.datetime.utcnow().isoformat()
        self._update_prop(bch, obj_uuid, 'id_perms', {'id_perms': id_perms})
    # end update_last_modified

    def uuid_to_obj_dict(self, id):
        try:
            obj_cols = self._obj_uuid_cf.get(id)
        except pycassa.NotFoundException:
            raise NoIdError(id)
        return obj_cols
    # end uuid_to_obj_dict

    def uuid_to_obj_perms(self, id):
        try:
            id_perms_json = self._obj_uuid_cf.get(
                id, columns=['prop:id_perms'])['prop:id_perms']
            id_perms = json.loads(id_perms_json)
        except pycassa.NotFoundException:
            raise NoIdError(id)
        return id_perms
    # end uuid_to_obj_perms

    def useragent_kv_store(self, key, value):
        columns = {'value': value}
        self._useragent_kv_cf.insert(key, columns)
    # end useragent_kv_store

    def useragent_kv_retrieve(self, key):
        if key:
            if isinstance(key, list):
                rows = self._useragent_kv_cf.multiget(key)
                return [rows[row].get('value') for row in rows]
            else:
                try:
                    columns = self._useragent_kv_cf.get(key)
                except pycassa.NotFoundException:
                    raise NoUserAgentKey
                return columns.get('value')
        else:  # no key specified, return entire contents
            kv_list = []
            for ua_key, ua_cols in self._useragent_kv_cf.get_range():
                kv_list.append({'key': ua_key, 'value': ua_cols.get('value')})
            return kv_list
    # end useragent_kv_retrieve

    def useragent_kv_delete(self, key):
        self._useragent_kv_cf.remove(key)
    # end useragent_kv_delete

    def walk(self, fn):
        walk_results = []
        obj_infos = [x for x in self._obj_uuid_cf.get_range(
                                          columns=['type', 'fq_name'],
                                          column_count=self._MAX_COL)]
        type_to_object = {}
        for obj_uuid, obj_col in obj_infos:
            try:
                obj_type = json.loads(obj_col['type'])
                obj_fq_name = json.loads(obj_col['fq_name'])
                # prep cache to avoid n/w round-trip in db.read for ref
                self.cache_uuid_to_fq_name_add(obj_uuid, obj_fq_name)

                try:
                    type_to_object[obj_type].append(obj_uuid)
                except KeyError:
                    type_to_object[obj_type] = [obj_uuid]
            except Exception as e:
                self.config_log('Error in db walk read %s' %(str(e)),
                                level=SandeshLevel.SYS_ERR)
                continue

        for obj_type, uuid_list in type_to_object.items():
            try:
                self.config_log('Resync: obj_type %s len %s'
                                %(obj_type, len(uuid_list)),
                                level=SandeshLevel.SYS_INFO)
                result = fn(obj_type, uuid_list)
                if result:
                    walk_results.append(result)
            except Exception as e:
                self.config_log('Error in db walk invoke %s' %(str(e)),
                                level=SandeshLevel.SYS_ERR)
                continue

        return walk_results
    # end walk
# end class VncCassandraClient


class VncServerKombuClient(VncKombuClient):
    def __init__(self, db_client_mgr, rabbit_ip, rabbit_port, ifmap_db,
                 rabbit_user, rabbit_password, rabbit_vhost, rabbit_ha_mode):
        self._db_client_mgr = db_client_mgr
        self._sandesh = db_client_mgr._sandesh
        self._ifmap_db = ifmap_db
        listen_port = db_client_mgr.get_server_port()
        q_name = 'vnc_config.%s-%s' %(socket.gethostname(), listen_port)
        super(VncServerKombuClient, self).__init__(
            rabbit_ip, rabbit_port, rabbit_user, rabbit_password, rabbit_vhost,
            rabbit_ha_mode, q_name, self._dbe_subscribe_callback, self.config_log)

    # end __init__

    def prepare_to_consume(self):
        self._db_client_mgr.wait_for_resync_done()
    # prepare_to_consume

    def config_log(self, msg, level):
        self._db_client_mgr.config_log(msg, level)
    # end config_log

    def dbe_oper_publish_pending(self):
        return self.num_pending_messages()
    # end dbe_oper_publish_pending

    @ignore_exceptions
    def _generate_msgbus_notify_trace(self, oper_info):
        req_id = oper_info.get('request-id',
            'req-%s' %(str(uuid.uuid4())))
        gevent.getcurrent().trace_request_id = req_id

        notify_trace = MessageBusNotifyTrace(request_id=req_id)
        notify_trace.operation = oper_info.get('oper', '')
        notify_trace.body = json.dumps(oper_info)

        return notify_trace
    # end _generate_msgbus_notify_trace

    def _dbe_subscribe_callback(self, oper_info):
        self._db_client_mgr.wait_for_resync_done()
        try:
            msg = "Notification Message: %s" %(pformat(oper_info))
            self.config_log(msg, level=SandeshLevel.SYS_DEBUG)
            trace = self._generate_msgbus_notify_trace(oper_info)

            if oper_info['oper'] == 'CREATE':
                self._dbe_create_notification(oper_info)
            if oper_info['oper'] == 'UPDATE':
                self._dbe_update_notification(oper_info)
            elif oper_info['oper'] == 'DELETE':
                self._dbe_delete_notification(oper_info)

            trace_msg(trace, 'MessageBusNotifyTraceBuf', self._sandesh)
        except Exception as e:
            string_buf = cStringIO.StringIO()
            cgitb.Hook(file=string_buf, format="text").handle(sys.exc_info())
            errmsg = string_buf.getvalue()
            self.config_log(string_buf.getvalue(),
                level=SandeshLevel.SYS_ERR)
            trace_msg(trace, name='MessageBusNotifyTraceBuf',
                              sandesh=self._sandesh, error_msg=errmsg)
    #end _dbe_subscribe_callback

    def dbe_create_publish(self, obj_type, obj_ids, obj_dict):
        req_id = get_trace_id()
        oper_info = {'request-id': req_id,
                     'oper': 'CREATE',
                     'type': obj_type,
                     'obj_dict': obj_dict}
        oper_info.update(obj_ids)
        self.publish(oper_info)
    # end dbe_create_publish

    def _dbe_create_notification(self, obj_info):
        obj_dict = obj_info['obj_dict']

        try:
            r_class = self._db_client_mgr.get_resource_class(obj_info['type'])
            if r_class:
                r_class.dbe_create_notification(obj_info, obj_dict)
        except Exception as e:
            err_msg = ("Failed in type specific dbe_create_notification " +
                       str(e))
            self.config_log(err_msg, level=SandeshLevel.SYS_ERR)
            raise
        finally:
            method_name = obj_info['type'].replace('-', '_')
            method = getattr(self._ifmap_db, "_ifmap_%s_create" % (method_name))
            (ok, result) = method(obj_info, obj_dict)
            if not ok:
                self.config_log(result, level=SandeshLevel.SYS_ERR)
                raise Exception(result)
    #end _dbe_create_notification

    def dbe_update_publish(self, obj_type, obj_ids):
        oper_info = {'oper': 'UPDATE', 'type': obj_type}
        oper_info.update(obj_ids)
        self.publish(oper_info)
    # end dbe_update_publish

    def _dbe_update_notification(self, obj_info):
        (ok, result) = self._db_client_mgr.dbe_read(obj_info['type'], obj_info)
        if not ok:
            raise Exception(result)

        new_obj_dict = result

        try:
            r_class = self._db_client_mgr.get_resource_class(obj_info['type'])
            if r_class:
                r_class.dbe_update_notification(obj_info)
        except:
            msg = "Failed to invoke type specific dbe_update_notification"
            self.config_log(msg, level=SandeshLevel.SYS_ERR)
            raise
        finally:
            ifmap_id = self._db_client_mgr.uuid_to_ifmap_id(obj_info['type'],
                                                            obj_info['uuid'])
            method_name = obj_info['type'].replace('-', '_')
            method = getattr(self._ifmap_db, "_ifmap_%s_update" % (method_name))
            (ok, ifmap_result) = method(ifmap_id, new_obj_dict)
            if not ok:
                raise Exception(ifmap_result)
    #end _dbe_update_notification

    def dbe_delete_publish(self, obj_type, obj_ids, obj_dict):
        oper_info = {'oper': 'DELETE', 'type': obj_type, 'obj_dict': obj_dict}
        oper_info.update(obj_ids)
        self.publish(oper_info)
    # end dbe_delete_publish

    def _dbe_delete_notification(self, obj_info):
        obj_dict = obj_info['obj_dict']

        db_client_mgr = self._db_client_mgr
        db_client_mgr._cassandra_db.cache_uuid_to_fq_name_del(obj_dict['uuid'])

        try:
            r_class = self._db_client_mgr.get_resource_class(obj_info['type'])
            if r_class:
                r_class.dbe_delete_notification(obj_info, obj_dict)
        except:
            msg = "Failed to invoke type specific dbe_delete_notification"
            self.config_log(msg, level=SandeshLevel.SYS_ERR)
            raise
        finally:
            method_name = obj_info['type'].replace('-', '_')
            method = getattr(self._ifmap_db, "_ifmap_%s_delete" % (method_name))
            (ok, ifmap_result) = method(obj_info)
            if not ok:
                self.config_log(ifmap_result, level=SandeshLevel.SYS_ERR)
                raise Exception(ifmap_result)
    #end _dbe_delete_notification

# end class VncKombuClient


class VncZkClient(object):
    _SUBNET_PATH = "/api-server/subnets"
    _FQ_NAME_TO_UUID_PATH = "/fq-name-to-uuid"
    _MAX_SUBNET_ADDR_ALLOC = 65535

    def __init__(self, instance_id, zk_server_ip, reset_config, db_prefix,
                 sandesh_hdl):
        self._db_prefix = db_prefix
        if db_prefix:
            client_pfx = db_prefix + '-'
            zk_path_pfx = db_prefix + '/'
        else:
            client_pfx = ''
            zk_path_pfx = ''

        client_name = client_pfx + 'api-' + instance_id
        self._subnet_path = zk_path_pfx + self._SUBNET_PATH
        self._fq_name_to_uuid_path = zk_path_pfx + self._FQ_NAME_TO_UUID_PATH

        self._sandesh = sandesh_hdl
        while True:
            try:
                self._zk_client = ZookeeperClient(client_name, zk_server_ip,
                                                  self._sandesh)
                break
            except gevent.event.Timeout as e:
                pass

        if reset_config:
            self._zk_client.delete_node(self._subnet_path, True);
            self._zk_client.delete_node(self._fq_name_to_uuid_path, True);
        self._subnet_allocators = {}
    # end __init__

    def create_subnet_allocator(self, subnet, subnet_alloc_list,
                                addr_from_start):
        # TODO handle subnet resizing change, ignore for now
        if subnet not in self._subnet_allocators:
            if addr_from_start is None:
                addr_from_start = False
            self._subnet_allocators[subnet] = IndexAllocator(
                self._zk_client, self._subnet_path+'/'+subnet+'/',
                size=0, start_idx=0, reverse=not addr_from_start,
                alloc_list=subnet_alloc_list,
		max_alloc=self._MAX_SUBNET_ADDR_ALLOC)
    # end create_subnet_allocator

    def delete_subnet_allocator(self, subnet):
        self._subnet_allocators.pop(subnet, None)
        IndexAllocator.delete_all(self._zk_client,
                                  self._subnet_path+'/'+subnet+'/')
    # end delete_subnet_allocator

    def _get_subnet_allocator(self, subnet):
        return self._subnet_allocators.get(subnet)
    # end _get_subnet_allocator

    def subnet_is_addr_allocated(self, subnet, addr):
        allocator = self._get_subnet_allocator(subnet)
        return allocator.read(addr)
    # end subnet_is_addr_allocated

    def subnet_alloc_req(self, subnet, addr=None):
        allocator = self._get_subnet_allocator(subnet)
        try:
            if addr is not None:
                if allocator.read(addr) is not None:
                    return addr
                else:
                    return allocator.reserve(addr)
            else:
                return allocator.alloc()
        except ResourceExhaustionError:
            return None
    # end subnet_alloc_req

    def subnet_free_req(self, subnet, addr):
        allocator = self._get_subnet_allocator(subnet)
        if allocator:
            allocator.delete(addr)
    # end subnet_free_req

    def create_fq_name_to_uuid_mapping(self, obj_type, fq_name, id):
        fq_name_str = ':'.join(fq_name)
        zk_path = self._fq_name_to_uuid_path+'/%s:%s' %(obj_type.replace('-', '_'),
                                             fq_name_str)
        self._zk_client.create_node(zk_path, id)
    # end create_fq_name_to_uuid_mapping

    def delete_fq_name_to_uuid_mapping(self, obj_type, fq_name):
        fq_name_str = ':'.join(fq_name)
        zk_path = self._fq_name_to_uuid_path+'/%s:%s' %(obj_type.replace('-', '_'),
                                             fq_name_str)
        self._zk_client.delete_node(zk_path)
    # end delete_fq_name_to_uuid_mapping

    def is_connected(self):
        return self._zk_client.is_connected()
    # end is_connected

# end VncZkClient


class VncDbClient(object):
    def __init__(self, api_svr_mgr, ifmap_srv_ip, ifmap_srv_port, uname,
                 passwd, cass_srv_list,
                 rabbit_servers, rabbit_port, rabbit_user, rabbit_password,
                 rabbit_vhost, rabbit_ha_mode, reset_config=False,
                 zk_server_ip=None, db_prefix=''):

        self._api_svr_mgr = api_svr_mgr
        self._sandesh = api_svr_mgr._sandesh

        # certificate auth
        ssl_options = None
        if api_svr_mgr._args.use_certs:
            ssl_options = {
                'keyfile': api_svr_mgr._args.keyfile,
                'certfile': api_svr_mgr._args.certfile,
                'ca_certs': api_svr_mgr._args.ca_certs,
                'cert_reqs': ssl.CERT_REQUIRED,
                'ciphers': 'ALL'
            }

        self._db_resync_done = gevent.event.Event()

        msg = "Connecting to ifmap on %s:%s as %s" \
              % (ifmap_srv_ip, ifmap_srv_port, uname)
        self.config_log(msg, level=SandeshLevel.SYS_NOTICE)

        self._ifmap_db = VncIfmapClient(
            self, ifmap_srv_ip, ifmap_srv_port, uname, passwd, ssl_options)

        msg = "Connecting to cassandra on %s" % (cass_srv_list,)
        self.config_log(msg, level=SandeshLevel.SYS_NOTICE)

        self._cassandra_db = VncServerCassandraClient(
            self, cass_srv_list, reset_config, db_prefix)

        msg = "Connecting to zookeeper on %s" % (zk_server_ip)
        self.config_log(msg, level=SandeshLevel.SYS_NOTICE)
        self._zk_db = VncZkClient(api_svr_mgr._args.worker_id, zk_server_ip,
                                  reset_config, db_prefix, self.config_log)

        self._msgbus = VncServerKombuClient(self, rabbit_servers,
                                            rabbit_port, self._ifmap_db,
                                            rabbit_user, rabbit_password,
                                            rabbit_vhost, rabbit_ha_mode)
    # end __init__

    def _update_default_quota(self):
        """ Read the default quotas from the configuration
        and update it in the project object if not already
        updated.
        """
        default_quota = QuotaHelper.default_quota

        proj_id = self.fq_name_to_uuid('project',
                                       ['default-domain', 'default-project'])
        (ok, proj_dict) = self.dbe_read('project', {'uuid':proj_id})
        if not ok:
            return
        quota = QuotaType()

        proj_dict['quota'] = default_quota
        self.dbe_update('project', {'uuid':proj_id}, proj_dict)
    # end _update_default_quota

    def db_resync(self):
        # Read contents from cassandra and publish to ifmap
        mapclient = self._ifmap_db._mapclient
        start_time = datetime.datetime.utcnow()
        self._cassandra_db.walk(self._dbe_resync)
        self._ifmap_db._publish_to_ifmap_enqueue('publish_discovery', 1)
        self.config_log("Cassandra DB walk completed.",
            level=SandeshLevel.SYS_INFO)
        self._update_default_quota()
        end_time = datetime.datetime.utcnow()
        msg = "Time elapsed in syncing ifmap: %s" % (str(end_time - start_time))
        self.config_log(msg, level=SandeshLevel.SYS_DEBUG)
        self._db_resync_done.set()
    # end db_resync

    def wait_for_resync_done(self):
        self._db_resync_done.wait()
    # end wait_for_resync_done

    def db_check(self):
        # Read contents from cassandra and report any read exceptions
        check_results = self._cassandra_db.walk(self._dbe_check)

        return check_results
    # end db_check

    def db_read(self):
        # Read contents from cassandra
        read_results = self._cassandra_db.walk(self._dbe_read)
        return read_results
    # end db_check

    def _uuid_to_longs(self, id):
        msb_id = id.int >> 64
        lsb_id = id.int & ((1 << 64) - 1)
        return msb_id, lsb_id
    # end _uuid_to_longs

    def set_uuid(self, obj_type, obj_dict, id, persist=True):
        if persist:
            # set the mapping from name to uuid in zk to ensure single creator
            fq_name = obj_dict['fq_name']
            self._zk_db.create_fq_name_to_uuid_mapping(obj_type, fq_name,
                                                       str(id))

        # set uuid in the perms meta
        mslong, lslong = self._uuid_to_longs(id)
        obj_dict['id_perms']['uuid'] = {}
        obj_dict['id_perms']['uuid']['uuid_mslong'] = mslong
        obj_dict['id_perms']['uuid']['uuid_lslong'] = lslong

        obj_dict['uuid'] = str(id)

        return True
    # end set_uuid

    def _alloc_set_uuid(self, obj_type, obj_dict):
        id = uuid.uuid4()
        ok = self.set_uuid(obj_type, obj_dict, id)

        return (ok, obj_dict['uuid'])
    # end _alloc_set_uuid

    def match_uuid(self, obj_dict, obj_uuid):
        new_mslong, new_lslong = self._uuid_to_longs(uuid.UUID(obj_uuid))
        old_mslong = obj_dict['id_perms']['uuid']['uuid_mslong']
        old_lslong = obj_dict['id_perms']['uuid']['uuid_lslong']
        if new_mslong == old_mslong and new_lslong == old_lslong:
            return True

        return False
    # end match_uuid

    def update_subnet_uuid(self, vn_dict, do_update=False):
        vn_uuid = vn_dict.get('uuid')

        def _read_subnet_uuid(subnet):
            if vn_uuid is None:
                return None
            pfx = subnet['subnet']['ip_prefix']
            pfx_len = subnet['subnet']['ip_prefix_len']

            network = IPNetwork('%s/%s' % (pfx, pfx_len))
            subnet_key = '%s %s/%s' % (vn_uuid, str(network.ip), pfx_len)
            try:
                return self.useragent_kv_retrieve(subnet_key)
            except NoUserAgentKey:
                return None

        ipam_refs = vn_dict.get('network_ipam_refs', [])
        updated = False
        for ipam in ipam_refs:
            vnsn = ipam['attr']
            subnets = vnsn['ipam_subnets']
            for subnet in subnets:
                if subnet.get('subnet_uuid'):
                    continue

                subnet_uuid = _read_subnet_uuid(subnet) or str(uuid.uuid4())
                subnet['subnet_uuid'] = subnet_uuid
                if not updated:
                    updated = True

        if updated and do_update:
            self._cassandra_db._cassandra_virtual_network_update(vn_uuid,
                                                                 vn_dict)
    # end update_subnet_uuid

    def _dbe_resync(self, obj_type, obj_uuids):
        obj_class = self._api_svr_mgr.str_to_class(utils.CamelCase(obj_type))
        obj_fields = list(obj_class.prop_fields) + list(obj_class.ref_fields)
        (ok, obj_dicts) = self._cassandra_db.read(
                               obj_type, obj_uuids, field_names=obj_fields)
        for obj_dict in obj_dicts:
            # give chance for zk heartbeat/ping
            gevent.sleep(0)

            try:
                obj_uuid = obj_dict['uuid']
                # TODO remove backward compat (use RT instead of VN->LR ref)
                if (obj_type == 'virtual_network' and
                    'logical_router_refs' in obj_dict):
                    for router in obj_dict['logical_router_refs']:
                        self._cassandra_db._delete_ref(None, obj_type, obj_uuid,
                                                       'logical_router',
                                                       router['uuid'])

                if (obj_type == 'virtual_network' and
                    'network_ipam_refs' in obj_dict):
                    self.update_subnet_uuid(obj_dict, do_update=True)
            except Exception as e:
                self.config_object_error(
                    obj_dict.get('uuid'), None, obj_type,
                    'dbe_resync:cassandra_read', str(e))
                continue

            try:
                parent_type = obj_dict.get('parent_type', None)
                method = getattr(self._ifmap_db, "_ifmap_%s_alloc" % (obj_type))
                (ok, result) = method(parent_type, obj_dict['fq_name'])
                (my_imid, parent_imid) = result
            except Exception as e:
                self.config_object_error(
                    obj_uuid, None, obj_type, 'dbe_resync:ifmap_alloc', str(e))
                continue

            try:
                obj_ids = {'uuid': obj_uuid, 'imid': my_imid,
                           'parent_imid': parent_imid}
                method = getattr(self._ifmap_db, "_ifmap_%s_create" % (obj_type))
                (ok, result) = method(obj_ids, obj_dict)
            except Exception as e:
                self.config_object_error(
                    obj_uuid, None, obj_type, 'dbe_resync:ifmap_create', str(e))
                continue
        # end for all objects
    # end _dbe_resync


    def _dbe_check(self, obj_type, obj_uuids):
        for obj_uuid in obj_uuids:
            try:
                (ok, obj_dict) = self._cassandra_db.read(obj_type, [obj_uuid])
            except Exception as e:
                return {'uuid': obj_uuid, 'type': obj_type, 'error': str(e)}
     # end _dbe_check

    def _dbe_read(self, obj_type, obj_uuids):
        results = []
        for obj_uuid in obj_uuids:
            try:
                (ok, obj_dict) = self._cassandra_db.read(obj_type, [obj_uuid])
                result_dict = obj_dict[0]
                result_dict['type'] = obj_type
                result_dict['uuid'] = obj_uuid
                results.append(result_dict)
            except Exception as e:
                self.config_object_error(
                    obj_uuid, None, obj_type, '_dbe_read:cassandra_read', str(e))
                continue

        return results
    # end _dbe_read

    @ignore_exceptions
    def _generate_db_request_trace(self, oper, obj_type, obj_ids, obj_dict):
        req_id = get_trace_id()

        body = dict(obj_dict)
        body['type'] = obj_type
        body.update(obj_ids)
        db_trace = DBRequestTrace(request_id=req_id)
        db_trace.operation = oper
        db_trace.body = json.dumps(body)
        return db_trace
    # end _generate_db_request_trace

    # Public Methods
    # Returns created ifmap_id
    def dbe_alloc(self, obj_type, obj_dict, uuid_requested=None):
        try:
            if uuid_requested:
                obj_uuid = uuid_requested
                ok = self.set_uuid(obj_type, obj_dict,
                                   uuid.UUID(uuid_requested), False)
            else:
                (ok, obj_uuid) = self._alloc_set_uuid(obj_type, obj_dict)
        except ResourceExistsError as e:
            return (False, (409, str(e)))

        parent_type = obj_dict.get('parent_type', None)
        method_name = obj_type.replace('-', '_')
        method = getattr(self._ifmap_db, "_ifmap_%s_alloc" % (method_name))
        (ok, result) = method(parent_type, obj_dict['fq_name'])
        if not ok:
            self.dbe_release(obj_type, obj_dict['fq_name'])
            return False, result

        (my_imid, parent_imid) = result
        obj_ids = {
            'uuid': obj_dict['uuid'],
            'imid': my_imid, 'parent_imid': parent_imid}

        return (True, obj_ids)
    # end dbe_alloc

    def dbe_trace(oper):
        def wrapper1(func):
            def wrapper2(self, obj_type, obj_ids, obj_dict):
                trace = self._generate_db_request_trace(oper, obj_type,
                                                        obj_ids, obj_dict)
                try:
                    ret = func(self, obj_type, obj_ids, obj_dict)
                    trace_msg(trace, 'DBRequestTraceBuf',
                              self._sandesh)
                    return ret
                except Exception as e:
                    trace_msg(trace, 'DBRequestTraceBuf',
                              self._sandesh, error_msg=str(e))
                    raise

            return wrapper2
        return wrapper1
    # dbe_trace

    @dbe_trace('create')
    def dbe_create(self, obj_type, obj_ids, obj_dict):
        method_name = obj_type.replace('-', '_')
        (ok, result) = self._cassandra_db.create(method_name, obj_ids, obj_dict)

        # publish to ifmap via msgbus
        self._msgbus.dbe_create_publish(obj_type, obj_ids, obj_dict)

        return (ok, result)
    # end dbe_create

    # input id is ifmap-id + uuid
    def dbe_read(self, obj_type, obj_ids, obj_fields=None):
        method_name = obj_type.replace('-', '_')
        try:
            (ok, cassandra_result) = self._cassandra_db.read(method_name,
                                                             [obj_ids['uuid']],
                                                             obj_fields)
        except NoIdError as e:
            return (False, str(e))

        return (ok, cassandra_result[0])
    # end dbe_read

    def dbe_count_children(self, obj_type, obj_id, child_type):
        method_name = obj_type.replace('-', '_')
        try:
            (ok, cassandra_result) = self._cassandra_db.count_children(
                method_name, obj_id, child_type)
        except NoIdError as e:
            return (False, str(e))

        return (ok, cassandra_result)
    # end dbe_read

    def dbe_read_multi(self, obj_type, obj_ids_list, obj_fields=None):
        method_name = obj_type.replace('-', '_')
        try:
            (ok, cassandra_result) = self._cassandra_db.read(
                method_name, [obj_id['uuid'] for obj_id in obj_ids_list],
                obj_fields)
        except NoIdError as e:
            return (False, str(e))

        return (ok, cassandra_result)
    # end dbe_read_multi


    def dbe_is_latest(self, obj_ids, tstamp):
        try:
            is_latest = self._cassandra_db.is_latest(obj_ids['uuid'], tstamp)
            return (True, is_latest)
        except Exception as e:
            return (False, str(e))
    # end dbe_is_latest

    @dbe_trace('update')
    def dbe_update(self, obj_type, obj_ids, new_obj_dict):
        method_name = obj_type.replace('-', '_')
        (ok, cassandra_result) = self._cassandra_db.update(
            method_name, obj_ids['uuid'], new_obj_dict)

        # publish to ifmap via redis
        self._msgbus.dbe_update_publish(obj_type, obj_ids)

        return (ok, cassandra_result)
    # end dbe_update

    def dbe_list(self, obj_type, parent_uuids=None, back_ref_uuids=None,
                 obj_uuids=None, count=False, paginate_start=None,
                 paginate_count=None):
        method_name = obj_type.replace('-', '_')
        (ok, cassandra_result) = self._cassandra_db.list(
                 method_name, parent_uuids=parent_uuids,
                 back_ref_uuids=back_ref_uuids, obj_uuids=obj_uuids,
                 count=count)
        return (ok, cassandra_result)
    # end dbe_list

    @dbe_trace('delete')
    def dbe_delete(self, obj_type, obj_ids, obj_dict):
        method_name = obj_type.replace('-', '_')
        (ok, cassandra_result) = self._cassandra_db.delete(method_name,
                                                           obj_ids['uuid'])

        # publish to ifmap via redis
        self._msgbus.dbe_delete_publish(obj_type, obj_ids, obj_dict)

        # finally remove mapping in zk
        fq_name = cfgm_common.imid.get_fq_name_from_ifmap_id(obj_ids['imid'])
        self.dbe_release(obj_type, fq_name)

        return ok, cassandra_result
    # end dbe_delete

    def dbe_release(self, obj_type, obj_fq_name):
        self._zk_db.delete_fq_name_to_uuid_mapping(obj_type, obj_fq_name)
    # end dbe_release

    def dbe_cache_invalidate(self, obj_ids):
        pass
    # end dbe_cache_invalidate

    def dbe_oper_publish_pending(self):
        return self._msgbus.dbe_oper_publish_pending()
    # end dbe_oper_publish_pending

    def useragent_kv_store(self, key, value):
        self._cassandra_db.useragent_kv_store(key, value)
    # end useragent_kv_store

    def useragent_kv_retrieve(self, key):
        return self._cassandra_db.useragent_kv_retrieve(key)
    # end useragent_kv_retrieve

    def useragent_kv_delete(self, key):
        return self._cassandra_db.useragent_kv_delete(key)
    # end useragent_kv_delete

    def subnet_is_addr_allocated(self, subnet, addr):
        return self._zk_db.subnet_is_addr_allocated(subnet, addr)
    # end subnet_is_addr_allocated

    def subnet_alloc_req(self, subnet, addr=None):
        return self._zk_db.subnet_alloc_req(subnet, addr)
    # end subnet_alloc_req

    def subnet_free_req(self, subnet, addr):
        self._zk_db.subnet_free_req(subnet, addr)
    # end subnet_free_req

    def subnet_create_allocator(self, subnet, subnet_alloc_list,
                                addr_from_start):
        self._zk_db.create_subnet_allocator(subnet, subnet_alloc_list,
                                            addr_from_start)
    # end subnet_create_allocator

    def subnet_delete_allocator(self, subnet):
        self._zk_db.delete_subnet_allocator(subnet)
    # end subnet_delete_allocator

    def uuid_vnlist(self):
        return self._cassandra_db.uuid_vnlist()
    # end uuid_vnlist

    def uuid_to_ifmap_id(self, obj_type, id):
        fq_name = self.uuid_to_fq_name(id)
        return self.fq_name_to_ifmap_id(obj_type, fq_name)
    # end uuid_to_ifmap_id

    def fq_name_to_uuid(self, obj_type, fq_name):
        obj_uuid = self._cassandra_db.fq_name_to_uuid(obj_type, fq_name)
        return obj_uuid
    # end fq_name_to_uuid

    def uuid_to_fq_name(self, obj_uuid):
        return self._cassandra_db.uuid_to_fq_name(obj_uuid)
    # end uuid_to_fq_name

    def uuid_to_obj_type(self, obj_uuid):
        return self._cassandra_db.uuid_to_obj_type(obj_uuid)
    # end uuid_to_obj_type

    def ifmap_id_to_fq_name(self, ifmap_id):
        return self._ifmap_db.ifmap_id_to_fq_name(ifmap_id)
    # end ifmap_id_to_fq_name

    def fq_name_to_ifmap_id(self, obj_type, fq_name):
        return self._ifmap_db.fq_name_to_ifmap_id(obj_type, fq_name)
    # end fq_name_to_ifmap_id

    def uuid_to_obj_dict(self, obj_uuid):
        return self._cassandra_db.uuid_to_obj_dict(obj_uuid)
    # end uuid_to_obj_dict

    def uuid_to_obj_perms(self, obj_uuid):
        return self._cassandra_db.uuid_to_obj_perms(obj_uuid)
    # end uuid_to_obj_perms

    def ref_update(self, obj_type, obj_uuid, ref_type, ref_uuid, ref_data,
                   operation):
        self._cassandra_db.ref_update(obj_type, obj_uuid, ref_type, ref_uuid,
                                      ref_data, operation)
        self._msgbus.dbe_update_publish(obj_type.replace('_', '-'),
                                        {'uuid':obj_uuid})
        return obj_uuid
    # ref_update

    def get_resource_class(self, resource_type):
        return self._api_svr_mgr.get_resource_class(resource_type)
    # end get_resource_class

    # Helper routines for REST
    def generate_url(self, obj_type, obj_uuid):
        return self._api_svr_mgr.generate_url(obj_type, obj_uuid)
    # end generate_url

    def config_object_error(self, id, fq_name_str, obj_type,
                            operation, err_str):
        self._api_svr_mgr.config_object_error(
            id, fq_name_str, obj_type, operation, err_str)
    # end config_object_error

    def config_log(self, msg, level):
        self._api_svr_mgr.config_log(msg, level)
    # end config_log

    def get_server_port(self):
        return self._api_svr_mgr.get_server_port()
    # end get_server_port

# end class VncDbClient