path: root/tools/python/xen/xend/XendAPI.py

#============================================================================
# This library is free software; you can redistribute it and/or
# modify it under the terms of version 2.1 of the GNU Lesser General Public
# License as published by the Free Software Foundation.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#============================================================================
# Copyright (C) 2006-2007 XenSource Ltd.
#============================================================================

import inspect
import os
import Queue
import string
import sys
import traceback
import threading
import time
import xmlrpclib

# sets is deprecated as of python 2.6, but set is unavailable in 2.3
try:
    set
except NameError:
    from sets import Set as set

import XendDomain, XendDomainInfo, XendNode, XendDmesg
import XendLogging, XendTaskManager, XendAPIStore

from xen.xend import uuid as genuuid
from XendAPIVersion import *
from XendAuthSessions import instance as auth_manager
from XendError import *
from XendClient import ERROR_INVALID_DOMAIN
from XendLogging import log
from XendNetwork import XendNetwork
from XendTask import XendTask
from XendPIFMetrics import XendPIFMetrics
from XendVMMetrics import XendVMMetrics
from XendPIF import XendPIF
from XendPBD import XendPBD
from XendPPCI import XendPPCI
from XendDPCI import XendDPCI
from XendPSCSI import XendPSCSI, XendPSCSI_HBA
from XendDSCSI import XendDSCSI, XendDSCSI_HBA
from XendXSPolicy import XendXSPolicy, XendACMPolicy
from xen.xend.XendCPUPool import XendCPUPool

from XendAPIConstants import *
from xen.util.xmlrpclib2 import stringify

from xen.util.blkif import blkdev_name_to_number
from xen.util import xsconstants


AUTH_NONE = 'none'
AUTH_PAM = 'pam'

argcounts = {}

# ------------------------------------------
# Utility Methods for Xen API Implementation
# ------------------------------------------

def xen_api_success(value):
    """Wraps a return value in XenAPI format."""
    if value is None:
        s = ''
    else:
        s = stringify(value)
    return {"Status": "Success", "Value": s}

def xen_api_success_void():
    """Return success, but caller expects no return value."""
    return xen_api_success("")

def xen_api_error(error):
    """Wraps an error value in XenAPI format."""
    if type(error) == tuple:
        error = list(error)
    if type(error) != list:
        error = [error]
    if len(error) == 0:
        error = ['INTERNAL_ERROR', 'Empty list given to xen_api_error']

    return { "Status": "Failure",
             "ErrorDescription": [str(x) for x in error] }


def xen_api_todo():
    """Temporary method to make sure we track down all the TODOs"""
    return {"Status": "Error", "ErrorDescription": XEND_ERROR_TODO}


def now():
    return datetime()


def datetime(when = None):
    """Marshall the given time as a Xen-API DateTime.

    @param when The time in question, given as seconds since the epoch, UTC.
                May be None, in which case the current time is used.
    """
    if when is None:
        return xmlrpclib.DateTime(time.gmtime())
    else:
        return xmlrpclib.DateTime(time.gmtime(when))


# ---------------------------------------------------
# Event dispatch
# ---------------------------------------------------

EVENT_QUEUE_LENGTH = 50
event_registrations = {}

def event_register(session, reg_classes):
    if session not in event_registrations:
        event_registrations[session] = {
            'classes' : set(),
            'queue'   : Queue.Queue(EVENT_QUEUE_LENGTH),
            'next-id' : 1
            }
    if not reg_classes:
        reg_classes = classes
    sessionclasses = event_registrations[session]['classes']
    if hasattr(sessionclasses, 'union_update'):
        sessionclasses.union_update(reg_classes)
    else:
        sessionclasses.update(reg_classes)



def event_unregister(session, unreg_classes):
    if session not in event_registrations:
        return

    if unreg_classes:
        event_registrations[session]['classes'].intersection_update(
            unreg_classes)
        if len(event_registrations[session]['classes']) == 0:
            del event_registrations[session]
    else:
        del event_registrations[session]


def event_next(session):
    if session not in event_registrations:
        return xen_api_error(['SESSION_NOT_REGISTERED', session])
    queue = event_registrations[session]['queue']
    events = [queue.get()]
    try:
        while True:
            events.append(queue.get(False))
    except Queue.Empty:
        pass

    return xen_api_success(events)


def _ctor_event_dispatch(xenapi, ctor, api_cls, session, args):
    result = ctor(xenapi, session, *args)
    if result['Status'] == 'Success':
        ref = result['Value']
        event_dispatch('add', api_cls, ref, '')
    return result


def _dtor_event_dispatch(xenapi, dtor, api_cls, session, ref, args):
    result = dtor(xenapi, session, ref, *args)
    if result['Status'] == 'Success':
        event_dispatch('del', api_cls, ref, '')
    return result


def _setter_event_dispatch(xenapi, setter, api_cls, attr_name, session, ref,
                           args):
    result = setter(xenapi, session, ref, *args)
    if result['Status'] == 'Success':
        event_dispatch('mod', api_cls, ref, attr_name)
    return result


def event_dispatch(operation, api_cls, ref, attr_name):
    assert operation in ['add', 'del', 'mod']
    event = {
        'timestamp' : now(),
        'class'     : api_cls,
        'operation' : operation,
        'ref'       : ref,
        'obj_uuid'  : ref,
        'field'     : attr_name,
        }
    for reg in event_registrations.values():
        if api_cls in reg['classes']:
            event['id'] = reg['next-id']
            reg['next-id'] += 1
            reg['queue'].put(event)


# ---------------------------------------------------
# Python Method Decorators for input value validation
# ---------------------------------------------------

def trace(func, api_name = ''):
    """Decorator to trace XMLRPC Xen API methods.

    @param func: function with any parameters
    @param api_name: name of the api call for debugging.
    """
    if hasattr(func, 'api'):
        api_name = func.api
    def trace_func(self, *args, **kwargs):
        log.debug('%s: %s' % (api_name, args))
        return func(self, *args, **kwargs)
    trace_func.api = api_name
    return trace_func


def catch_typeerror(func):
    """Decorator to catch any TypeErrors and translate them into Xen-API
    errors.

    @param func: function with params: (self, ...)
    @rtype: callable object
    """
    def f(self, *args, **kwargs):
        try:
            return func(self, *args, **kwargs)
        except TypeError, exn:
            #log.exception('catch_typeerror')
            if hasattr(func, 'api') and func.api in argcounts:
                # Assume that if the argument count was wrong and if the
                # exception was thrown inside this file, then it is due to an
                # invalid call from the client, otherwise it's an internal
                # error (which will be handled further up).
                expected = argcounts[func.api]
                actual = len(args) + len(kwargs)
                if expected != actual:
                    tb = sys.exc_info()[2]
                    try:
                        sourcefile = traceback.extract_tb(tb)[-1][0]
                        if sourcefile == inspect.getsourcefile(XendAPI):
                            return xen_api_error(
                                ['MESSAGE_PARAMETER_COUNT_MISMATCH',
                                 func.api, expected, actual])
                    finally:
                        del tb
            raise
        except XendAPIError, exn:
            return xen_api_error(exn.get_api_error())

    return f


def session_required(func):
    """Decorator to verify if session is valid before calling method.

    @param func: function with params: (self, session, ...)
    @rtype: callable object
    """    
    def check_session(self, session, *args, **kwargs):
        if auth_manager().is_session_valid(session):
            return func(self, session, *args, **kwargs)
        else:
            return xen_api_error(['SESSION_INVALID', session])

    return check_session


def _is_valid_ref(ref, validator):
    return type(ref) == str and validator(ref)

def _check_ref(validator, clas, func, api, session, ref, *args, **kwargs):
    if _is_valid_ref(ref, validator):
        return func(api, session, ref, *args, **kwargs)
    else:
        return xen_api_error(['HANDLE_INVALID', clas, ref])


def valid_host(func):
    """Decorator to verify if host_ref is valid before calling method.

    @param func: function with params: (self, session, host_ref, ...)
    @rtype: callable object
    """
    return lambda *args, **kwargs: \
           _check_ref(XendNode.instance().is_valid_host,
                      'host', func, *args, **kwargs)

def valid_host_metrics(func):
    """Decorator to verify if host_metrics_ref is valid before calling
    method.

    @param func: function with params: (self, session, host_metrics_ref)
    @rtype: callable object
    """
    return lambda *args, **kwargs: \
           _check_ref(lambda r: r == XendNode.instance().host_metrics_uuid,
                      'host_metrics', func, *args, **kwargs)

def valid_host_cpu(func):
    """Decorator to verify if host_cpu_ref is valid before calling method.

    @param func: function with params: (self, session, host_cpu_ref, ...)
    @rtype: callable object
    """    
    return lambda *args, **kwargs: \
           _check_ref(XendNode.instance().is_valid_cpu,
                      'host_cpu', func, *args, **kwargs)

def valid_vm(func):
    """Decorator to verify if vm_ref is valid before calling method.

    @param func: function with params: (self, session, vm_ref, ...)
    @rtype: callable object
    """    
    return lambda *args, **kwargs: \
           _check_ref(XendDomain.instance().is_valid_vm,
                      'VM', func, *args, **kwargs)

def valid_vbd(func):
    """Decorator to verify if vbd_ref is valid before calling method.

    @param func: function with params: (self, session, vbd_ref, ...)
    @rtype: callable object
    """    
    return lambda *args, **kwargs: \
           _check_ref(lambda r: XendDomain.instance().is_valid_dev('vbd', r),
                      'VBD', func, *args, **kwargs)

def valid_vbd_metrics(func):
    """Decorator to verify if ref is valid before calling method.

    @param func: function with params: (self, session, ref, ...)
    @rtype: callable object
    """    
    return lambda *args, **kwargs: \
           _check_ref(lambda r: XendDomain.instance().is_valid_dev('vbd', r),
                      'VBD_metrics', func, *args, **kwargs)

def valid_vif(func):
    """Decorator to verify if vif_ref is valid before calling method.

    @param func: function with params: (self, session, vif_ref, ...)
    @rtype: callable object
    """
    return lambda *args, **kwargs: \
           _check_ref(lambda r: XendDomain.instance().is_valid_dev('vif', r),
                      'VIF', func, *args, **kwargs)

def valid_vif_metrics(func):
    """Decorator to verify if ref is valid before calling method.

    @param func: function with params: (self, session, ref, ...)
    @rtype: callable object
    """    
    return lambda *args, **kwargs: \
           _check_ref(lambda r: XendDomain.instance().is_valid_dev('vif', r),
                      'VIF_metrics', func, *args, **kwargs)

def valid_vdi(func):
    """Decorator to verify if vdi_ref is valid before calling method.

    @param func: function with params: (self, session, vdi_ref, ...)
    @rtype: callable object
    """
    return lambda *args, **kwargs: \
           _check_ref(XendNode.instance().is_valid_vdi,
                      'VDI', func, *args, **kwargs)

def valid_console(func):
    """Decorator to verify if console_ref is valid before calling method.

    @param func: function with params: (self, session, console_ref, ...)
    @rtype: callable object
    """
    return lambda *args, **kwargs: \
           _check_ref(lambda r: XendDomain.instance().is_valid_dev('console',
                                                                   r),
                      'console', func, *args, **kwargs)

def valid_sr(func):
    """Decorator to verify if sr_ref is valid before calling method.

    @param func: function with params: (self, session, sr_ref, ...)
    @rtype: callable object
    """
    return lambda *args, **kwargs: \
           _check_ref(lambda r: XendNode.instance().is_valid_sr,
                      'SR', func, *args, **kwargs)

def valid_task(func):
    """Decorator to verify if task_ref is valid before calling
    method.

    @param func: function with params: (self, session, task_ref)
    @rtype: callable object
    """
    return lambda *args, **kwargs: \
           _check_ref(XendTaskManager.get_task,
                      'task', func, *args, **kwargs)

def valid_debug(func):
    """Decorator to verify if task_ref is valid before calling
    method.

    @param func: function with params: (self, session, task_ref)
    @rtype: callable object
    """
    return lambda *args, **kwargs: \
           _check_ref(lambda r: r in XendAPI._debug,
                      'debug', func, *args, **kwargs)


def valid_object(class_name):
    """Decorator to verify if object is valid before calling
    method.

    @param func: function with params: (self, session, pif_ref)
    @rtype: callable object
    """
    return lambda func: \
           lambda *args, **kwargs: \
           _check_ref(lambda r: \
                          XendAPIStore.get(r, class_name) is not None,
                      class_name, func, *args, **kwargs)

# -----------------------------
# Bridge to Legacy XM API calls
# -----------------------------

def do_vm_func(fn_name, vm_ref, *args, **kwargs):
    """Helper wrapper func to abstract away from repetitive code.

    @param fn_name: function name for XendDomain instance
    @type fn_name: string
    @param vm_ref: vm_ref
    @type vm_ref: string
    @param *args: more arguments
    @type *args: tuple
    """
    try:
        xendom = XendDomain.instance()
        fn = getattr(xendom, fn_name)
        xendom.do_legacy_api_with_uuid(fn, vm_ref, *args, **kwargs)
        return xen_api_success_void()
    except VMBadState, exn:
        return xen_api_error(['VM_BAD_POWER_STATE', vm_ref, exn.expected,
                              exn.actual])


classes = {
    'session'      : None,
    'event'        : None,
    'host'         : valid_host,
    'host_cpu'     : valid_host_cpu,
    'host_metrics' : valid_host_metrics,
    'VM'           : valid_vm,
    'VBD'          : valid_vbd,
    'VBD_metrics'  : valid_vbd_metrics,
    'VIF'          : valid_vif,
    'VIF_metrics'  : valid_vif_metrics,
    'VDI'          : valid_vdi,
    'console'      : valid_console,
    'SR'           : valid_sr,
    'task'         : valid_task,
    'XSPolicy'     : valid_object("XSPolicy"),
    'ACMPolicy'    : valid_object("ACMPolicy"),
    'debug'        : valid_debug,
    'network'      : valid_object("network"),
    'PIF'          : valid_object("PIF"),
    'VM_metrics'   : valid_object("VM_metrics"),
    'PBD'          : valid_object("PBD"),
    'PIF_metrics'  : valid_object("PIF_metrics"),
    'PPCI'         : valid_object("PPCI"),
    'DPCI'         : valid_object("DPCI"),
    'PSCSI'        : valid_object("PSCSI"),
    'PSCSI_HBA'    : valid_object("PSCSI_HBA"),
    'DSCSI'        : valid_object("DSCSI"),
    'DSCSI_HBA'    : valid_object("DSCSI_HBA"),
    'cpu_pool'     : valid_object("cpu_pool"),
}

autoplug_classes = {
    'network'     : XendNetwork,
    'PIF'         : XendPIF,
    'VM_metrics'  : XendVMMetrics,
    'PBD'         : XendPBD,
    'PIF_metrics' : XendPIFMetrics,
    'PPCI'        : XendPPCI,
    'DPCI'        : XendDPCI,
    'PSCSI'       : XendPSCSI,
    'PSCSI_HBA'   : XendPSCSI_HBA,
    'DSCSI'       : XendDSCSI,
    'DSCSI_HBA'   : XendDSCSI_HBA,
    'XSPolicy'    : XendXSPolicy,
    'ACMPolicy'   : XendACMPolicy,
    'cpu_pool'    : XendCPUPool,
}

class XendAPI(object):
    """Implementation of the Xen-API in Xend. Expects to be
    used via XMLRPCServer.

    All methods that need a valid session are marked with
    a L{session_required} decorator that will
    transparently perform the required session authentication.

    We need to support Python <2.4, so we use the old decorator syntax.

    All XMLRPC accessible methods require an 'api' attribute and
    is set to the XMLRPC function name which the method implements.
    """

    __decorated__ = False
    __init_lock__ = threading.Lock()
    _debug = {}
    
    def __new__(cls, *args, **kwds):
        """ Override __new__ to decorate the class only once.

        Lock to make sure the classes are not decorated twice.
        """
        cls.__init_lock__.acquire()
        try:
            if not cls.__decorated__:
                cls._decorate()
                cls.__decorated__ = True
                
            return object.__new__(cls, *args, **kwds)
        finally:
            cls.__init_lock__.release()
            
    def _decorate(cls):
        """ Decorate all the object methods to have validators
        and appropriate function attributes.

        This should only be executed once for the duration of the
        server.
        """
        global_validators = [session_required, catch_typeerror]


        # Cheat methods
        # -------------
        # Methods that have a trivial implementation for all classes.
        # 1. get_by_uuid == getting by ref, so just return uuid for
        #    all get_by_uuid() methods.
        
        for api_cls in classes.keys():
            # We'll let the autoplug classes implement these functions
            # themselves - its much cleaner to do it in the base class
            if api_cls == 'session' or api_cls in autoplug_classes.keys():
                continue
            
            get_by_uuid = '%s_get_by_uuid' % api_cls
            get_uuid = '%s_get_uuid' % api_cls
            get_all_records = '%s_get_all_records' % api_cls    

            def _get_by_uuid(_1, _2, ref):
                return xen_api_success(ref)

            def _get_uuid(_1, _2, ref):
                return xen_api_success(ref)

            def unpack(v):
                return v.get('Value')

            def _get_all_records(_api_cls):
                return lambda s, session: \
                    xen_api_success(dict([(ref, unpack(getattr(cls, '%s_get_record' % _api_cls)(s, session, ref)))\
                                          for ref in unpack(getattr(cls, '%s_get_all' % _api_cls)(s, session))]))

            setattr(cls, get_by_uuid, _get_by_uuid)
            setattr(cls, get_uuid,    _get_uuid)
            setattr(cls, get_all_records, _get_all_records(api_cls))

        # Autoplugging classes
        # --------------------
        # These have all of their methods grabbed out from the implementation
        # class, and wrapped up to be compatible with the Xen-API.

        def getter(ref, type):
            return XendAPIStore.get(ref, type)
        
        for api_cls, impl_cls in autoplug_classes.items():
            def doit(n):           
                dot_n = '%s.%s' % (api_cls, n)
                full_n = '%s_%s' % (api_cls, n)
                if not hasattr(cls, full_n):
                    f = getattr(impl_cls, n)
                    argcounts[dot_n] = f.func_code.co_argcount + 1
                    g = lambda api_cls: \
                    setattr(cls, full_n, \
                            lambda s, session, ref, *args: \
                               xen_api_success( \
                                   f(getter(ref, api_cls), *args)))
                    g(api_cls) # Force api_cls to be captured
                    
            def doit_func(n):           
                dot_n = '%s.%s' % (api_cls, n)
                full_n = '%s_%s' % (api_cls, n)
                if not hasattr(cls, full_n):
                    f = getattr(impl_cls, n)
                    argcounts[dot_n] = f.func_code.co_argcount
                    setattr(cls, full_n, \
                            lambda s, session, *args: \
                               xen_api_success( \
                                   f(*args)))

            ro_attrs = impl_cls.getAttrRO()
            rw_attrs = impl_cls.getAttrRW()
            methods  = impl_cls.getMethods()
            funcs    = impl_cls.getFuncs()
            
            for attr_name in ro_attrs + rw_attrs:
                doit('get_%s' % attr_name)
            for attr_name in rw_attrs:
                doit('set_%s' % attr_name)
            for method in methods:
                doit('%s' % method)
            for func in funcs:
                doit_func('%s' % func)

        def wrap_method(name, new_f):
            try:
                f = getattr(cls, name)
                wrapped_f = (lambda *args: new_f(f, *args))
                wrapped_f.api = f.api
                wrapped_f.async = f.async
                setattr(cls, name, wrapped_f)
            except AttributeError:
                # Logged below (API call: %s not found)
                pass


        def setter_event_wrapper(api_cls, attr_name):
            setter_name = '%s_set_%s' % (api_cls, attr_name)
            wrap_method(
                setter_name,
                lambda setter, s, session, ref, *args:
                _setter_event_dispatch(s, setter, api_cls, attr_name,
                                       session, ref, args))


        def ctor_event_wrapper(api_cls):
            ctor_name = '%s_create' % api_cls
            wrap_method(
                ctor_name,
                lambda ctor, s, session, *args:
                _ctor_event_dispatch(s, ctor, api_cls, session, args))


        def dtor_event_wrapper(api_cls):
            dtor_name = '%s_destroy' % api_cls
            wrap_method(
                dtor_name,
                lambda dtor, s, session, ref, *args:
                _dtor_event_dispatch(s, dtor, api_cls, session, ref, args))


        # Wrapping validators around XMLRPC calls
        # ---------------------------------------

        for api_cls, validator in classes.items():
            def doit(n, takes_instance, async_support = False,
                     return_type = None):
                n_ = n.replace('.', '_')
                try:
                    f = getattr(cls, n_)
                    if n not in argcounts:
                        argcounts[n] = f.func_code.co_argcount - 1
                    
                    validators = takes_instance and validator and \
                                 [validator] or []

                    validators += global_validators
                    for v in validators:
                        f = v(f)
                        f.api = n
                        f.async = async_support
                        if return_type:
                            f.return_type = return_type
                    
                    setattr(cls, n_, f)
                except AttributeError:
                    log.warn("API call: %s not found" % n)

            if api_cls in autoplug_classes.keys():
                impl_cls = autoplug_classes[api_cls]
                ro_attrs = impl_cls.getAttrRO()
                rw_attrs = impl_cls.getAttrRW()
                methods  = map(lambda x: (x, ""), impl_cls.getMethods())
                funcs    = map(lambda x: (x, ""), impl_cls.getFuncs())
            else:
                ro_attrs = getattr(cls, '%s_attr_ro' % api_cls, []) \
                           + cls.Base_attr_ro
                rw_attrs = getattr(cls, '%s_attr_rw' % api_cls, []) \
                           + cls.Base_attr_rw
                methods  = getattr(cls, '%s_methods' % api_cls, []) \
                           + cls.Base_methods
                funcs    = getattr(cls, '%s_funcs'   % api_cls, []) \
                           + cls.Base_funcs

            # wrap validators around readable class attributes
            for attr_name in ro_attrs + rw_attrs:
                doit('%s.get_%s' % (api_cls, attr_name), True,
                     async_support = False)

            # wrap validators around writable class attrributes
            for attr_name in rw_attrs:
                doit('%s.set_%s' % (api_cls, attr_name), True,
                     async_support = False)
                setter_event_wrapper(api_cls, attr_name)

            # wrap validators around methods
            for method_name, return_type in methods:
                doit('%s.%s' % (api_cls, method_name), True,
                     async_support = True)

            # wrap validators around class functions
            for func_name, return_type in funcs:
                doit('%s.%s' % (api_cls, func_name), False,
                     async_support = True,
                     return_type = return_type)

            ctor_event_wrapper(api_cls)
            dtor_event_wrapper(api_cls)


    _decorate = classmethod(_decorate)

    def __init__(self, auth):
        self.auth = auth

    Base_attr_ro = ['uuid']
    Base_attr_rw = []
    Base_methods = [('get_record', 'Struct')]
    Base_funcs   = [('get_all', 'Set'), ('get_by_uuid', None), ('get_all_records', 'Set')]

    # Xen API: Class Session
    # ----------------------------------------------------------------
    # NOTE: Left unwrapped by __init__

    session_attr_ro = ['this_host', 'this_user', 'last_active']
    session_methods = [('logout', None)]

    def session_get_all(self, session):
        return xen_api_success([session])

    def session_login_with_password(self, *args):
        if len(args) != 2:
            return xen_api_error(
                ['MESSAGE_PARAMETER_COUNT_MISMATCH',
                 'session.login_with_password', 2, len(args)])
        username = args[0]
        password = args[1]
        try:
            session = ((self.auth == AUTH_NONE and
                        auth_manager().login_unconditionally(username)) or
                       auth_manager().login_with_password(username, password))
            return xen_api_success(session)
        except XendError, e:
            return xen_api_error(['SESSION_AUTHENTICATION_FAILED'])
    session_login_with_password.api = 'session.login_with_password'

    # object methods
    def session_logout(self, session):
        auth_manager().logout(session)
        return xen_api_success_void()

    def session_get_record(self, session, self_session):
        if self_session != session:
            return xen_api_error(['PERMISSION_DENIED'])
        record = {'uuid'       : session,
                  'this_host'  : XendNode.instance().uuid,
                  'this_user'  : auth_manager().get_user(session),
                  'last_active': now()}
        return xen_api_success(record)

    def session_get_uuid(self, session, self_session):
        return xen_api_success(self_session)

    def session_get_by_uuid(self, session, self_session):
        return xen_api_success(self_session)

    # attributes (ro)
    def session_get_this_host(self, session, self_session):
        if self_session != session:
            return xen_api_error(['PERMISSION_DENIED'])
        return xen_api_success(XendNode.instance().uuid)

    def session_get_this_user(self, session, self_session):
        if self_session != session:
            return xen_api_error(['PERMISSION_DENIED'])
        user = auth_manager().get_user(session)
        if user is not None:
            return xen_api_success(user)
        return xen_api_error(['SESSION_INVALID', session])

    def session_get_last_active(self, session, self_session):
        if self_session != session:
            return xen_api_error(['PERMISSION_DENIED'])
        return xen_api_success(now())


    # Xen API: Class User
    # ----------------------------------------------------------------
    # TODO: NOT IMPLEMENTED YET

    # Xen API: Class Tasks
    # ----------------------------------------------------------------

    task_attr_ro = ['name_label',
                    'name_description',
                    'status',
                    'progress',
                    'type',
                    'result',
                    'error_info',
                    'allowed_operations',
                    'session'
                    ]

    task_attr_rw = []

    task_funcs = [('get_by_name_label', 'Set(task)'),
                  ('cancel', None)]

    def task_get_name_label(self, session, task_ref):
        task = XendTaskManager.get_task(task_ref)
        return xen_api_success(task.name_label)

    def task_get_name_description(self, session, task_ref):
        task = XendTaskManager.get_task(task_ref)
        return xen_api_success(task.name_description)

    def task_get_status(self, session, task_ref):
        task = XendTaskManager.get_task(task_ref)
        return xen_api_success(task.get_status())

    def task_get_progress(self, session, task_ref):
        task = XendTaskManager.get_task(task_ref)
        return xen_api_success(task.progress)

    def task_get_type(self, session, task_ref):
        task = XendTaskManager.get_task(task_ref)
        return xen_api_success(task.type)

    def task_get_result(self, session, task_ref):
        task = XendTaskManager.get_task(task_ref)
        return xen_api_success(task.result)

    def task_get_error_info(self, session, task_ref):
        task = XendTaskManager.get_task(task_ref)
        return xen_api_success(task.error_info)

    def task_get_allowed_operations(self, session, task_ref):
        return xen_api_success({})

    def task_get_session(self, session, task_ref):
        task = XendTaskManager.get_task(task_ref)
        return xen_api_success(task.session)

    def task_get_all(self, session):
        tasks = XendTaskManager.get_all_tasks()
        return xen_api_success(tasks)

    def task_get_record(self, session, task_ref):
        task = XendTaskManager.get_task(task_ref)
        return xen_api_success(task.get_record())

    def task_cancel(self, session, task_ref):
        return xen_api_error('OPERATION_NOT_ALLOWED')

    def task_get_by_name_label(self, session, name):
        return xen_api_success(XendTaskManager.get_task_by_name(name))

    # Xen API: Class host
    # ----------------------------------------------------------------    

    host_attr_ro = ['software_version',
                    'resident_VMs',
                    'PBDs',
                    'PIFs',
                    'PPCIs',
                    'PSCSIs',
                    'PSCSI_HBAs',
                    'host_CPUs',
                    'cpu_configuration',
                    'metrics',
                    'capabilities',
                    'supported_bootloaders',
                    'sched_policy',
                    'API_version_major',
                    'API_version_minor',
                    'API_version_vendor',
                    'API_version_vendor_implementation',
                    'enabled',
                    'resident_cpu_pools']
    
    host_attr_rw = ['name_label',
                    'name_description',
                    'other_config',
                    'logging']

    host_methods = [('disable', None),
                    ('enable', None),
                    ('reboot', None),
                    ('shutdown', None),
                    ('add_to_other_config', None),
                    ('remove_from_other_config', None),
                    ('dmesg', 'String'),
                    ('dmesg_clear', 'String'),
                    ('get_log', 'String'),
                    ('send_debug_keys', None),
                    ('tmem_thaw', None),
                    ('tmem_freeze', None),
                    ('tmem_flush', None),
                    ('tmem_destroy', None),
                    ('tmem_list', None),
                    ('tmem_set_weight', None),
                    ('tmem_set_cap', None),
                    ('tmem_set_compress', None),
                    ('tmem_query_freeable_mb', None),
                    ('tmem_shared_auth', None)]
    
    host_funcs = [('get_by_name_label', None),
                  ('list_methods', None)]

    # attributes
    def host_get_name_label(self, session, host_ref):
        return xen_api_success(XendNode.instance().name)
    def host_set_name_label(self, session, host_ref, new_name):
        XendNode.instance().set_name(new_name)
        return xen_api_success_void()
    def host_get_name_description(self, session, host_ref):
        return xen_api_success(XendNode.instance().get_description())
    def host_set_name_description(self, session, host_ref, new_desc):
        XendNode.instance().set_description(new_desc)
        return xen_api_success_void()
    def host_get_other_config(self, session, host_ref):
        return xen_api_success(XendNode.instance().other_config)
    def host_set_other_config(self, session, host_ref, other_config):
        node = XendNode.instance()
        node.other_config = dict(other_config)
        node.save()
        return xen_api_success_void()
    def host_add_to_other_config(self, session, host_ref, key, value):
        node = XendNode.instance()
        node.other_config[key] = value
        node.save()
        return xen_api_success_void()
    def host_remove_from_other_config(self, session, host_ref, key):
        node = XendNode.instance()
        if key in node.other_config:
            del node.other_config[key]
            node.save()
        return xen_api_success_void()
    def host_get_API_version_major(self, _, ref):
        return xen_api_success(XEN_API_VERSION_MAJOR)
    def host_get_API_version_minor(self, _, ref):
        return xen_api_success(XEN_API_VERSION_MINOR)
    def host_get_API_version_vendor(self, _, ref):
        return xen_api_success(XEN_API_VERSION_VENDOR)
    def host_get_API_version_vendor_implementation(self, _, ref):
        return xen_api_success(XEN_API_VERSION_VENDOR_IMPLEMENTATION)
    def host_get_software_version(self, session, host_ref):
        return xen_api_success(XendNode.instance().xen_version())
    def host_get_enabled(self, _1, _2):
        return xen_api_success(XendDomain.instance().allow_new_domains())
    def host_get_resident_VMs(self, session, host_ref):
        return xen_api_success(XendDomain.instance().get_domain_refs())
    def host_get_PBDs(self, _, ref):
        return xen_api_success(XendPBD.get_all())
    def host_get_PIFs(self, session, ref):
        return xen_api_success(XendNode.instance().get_PIF_refs())
    def host_get_PPCIs(self, session, ref):
        return xen_api_success(XendNode.instance().get_PPCI_refs())
    def host_get_PSCSIs(self, session, ref):
        return xen_api_success(XendNode.instance().get_PSCSI_refs())
    def host_get_PSCSI_HBAs(self, session, ref):
        return xen_api_success(XendNode.instance().get_PSCSI_HBA_refs())
    def host_get_host_CPUs(self, session, host_ref):
        return xen_api_success(XendNode.instance().get_host_cpu_refs())
    def host_get_metrics(self, _, ref):
        return xen_api_success(XendNode.instance().host_metrics_uuid)
    def host_get_capabilities(self, session, host_ref):
        return xen_api_success(XendNode.instance().get_capabilities())
    def host_get_supported_bootloaders(self, session, host_ref):
        return xen_api_success(['pygrub'])
    def host_get_sched_policy(self, _, host_ref):
        return xen_api_success(XendNode.instance().get_vcpus_policy())
    def host_get_cpu_configuration(self, _, host_ref):
        return xen_api_success(XendNode.instance().get_cpu_configuration())
    def host_set_logging(self, _, host_ref, logging):
        return xen_api_todo()
    def host_get_logging(self, _, host_ref):
        return xen_api_todo()
    def host_get_resident_cpu_pools(self, _, host_ref):
        return xen_api_success(XendCPUPool.get_all())

    # object methods
    def host_disable(self, session, host_ref):
        XendDomain.instance().set_allow_new_domains(False)
        return xen_api_success_void()
    def host_enable(self, session, host_ref):
        XendDomain.instance().set_allow_new_domains(True)
        return xen_api_success_void()
    def host_reboot(self, session, host_ref):
        if not XendDomain.instance().allow_new_domains():
            return xen_api_error(XEND_ERROR_HOST_RUNNING)
        return xen_api_error(XEND_ERROR_UNSUPPORTED)
    def host_shutdown(self, session, host_ref):
        if not XendDomain.instance().allow_new_domains():
            return xen_api_error(XEND_ERROR_HOST_RUNNING)
        return xen_api_error(XEND_ERROR_UNSUPPORTED)        

    def host_dmesg(self, session, host_ref):
        return xen_api_success(XendDmesg.instance().info())

    def host_dmesg_clear(self, session, host_ref):
        return xen_api_success(XendDmesg.instance().clear())

    def host_get_log(self, session, host_ref):
        log_file = open(XendLogging.getLogFilename())
        log_buffer = log_file.read()
        log_buffer = log_buffer.replace('\b', ' ')
        log_buffer = log_buffer.replace('\f', '\n')
        log_file.close()
        return xen_api_success(log_buffer)

    def host_send_debug_keys(self, _, host_ref, keys):
        node = XendNode.instance()
        node.send_debug_keys(keys)
        return xen_api_success_void()

    def host_get_record(self, session, host_ref):
        node = XendNode.instance()
        dom = XendDomain.instance()
        record = {'uuid': node.uuid,
                  'name_label': node.name,
                  'name_description': '',
                  'API_version_major': XEN_API_VERSION_MAJOR,
                  'API_version_minor': XEN_API_VERSION_MINOR,
                  'API_version_vendor': XEN_API_VERSION_VENDOR,
                  'API_version_vendor_implementation':
                  XEN_API_VERSION_VENDOR_IMPLEMENTATION,
                  'software_version': node.xen_version(),
                  'enabled': XendDomain.instance().allow_new_domains(),
                  'other_config': node.other_config,
                  'resident_VMs': dom.get_domain_refs(),
                  'host_CPUs': node.get_host_cpu_refs(),
                  'cpu_configuration': node.get_cpu_configuration(),
                  'metrics': node.host_metrics_uuid,
                  'capabilities': node.get_capabilities(),
                  'supported_bootloaders': ['pygrub'],
                  'sched_policy': node.get_vcpus_policy(),
                  'logging': {},
                  'PIFs': XendPIF.get_all(),
                  'PBDs': XendPBD.get_all(),
                  'PPCIs': XendPPCI.get_all(),
                  'PSCSIs': XendPSCSI.get_all(),
                  'PSCSI_HBAs': XendPSCSI_HBA.get_all(),
                  'resident_cpu_pools': XendCPUPool.get_all(),
                 }
        return xen_api_success(record)

    def host_tmem_thaw(self, _, host_ref, cli_id):
        node = XendNode.instance()
        try:
            node.tmem_thaw(cli_id)
        except Exception, e:
            return xen_api_error(e)
        return xen_api_success_void()

    def host_tmem_freeze(self, _, host_ref, cli_id):
        node = XendNode.instance()
        try:
            node.tmem_freeze(cli_id)
        except Exception, e:
            return xen_api_error(e)
        return xen_api_success_void()

    def host_tmem_flush(self, _, host_ref, cli_id, pages):
        node = XendNode.instance()
        try:
            node.tmem_flush(cli_id, pages)
        except Exception, e:
            return xen_api_error(e)
        return xen_api_success_void()

    def host_tmem_destroy(self, _, host_ref, cli_id):
        node = XendNode.instance()
        try:
            node.tmem_destroy(cli_id)
        except Exception, e:
            return xen_api_error(e)
        return xen_api_success_void()

    def host_tmem_list(self, _, host_ref, cli_id, use_long):
        node = XendNode.instance()
        try:
            info = node.tmem_list(cli_id, use_long)
        except Exception, e:
            return xen_api_error(e)
        return xen_api_success(info)

    def host_tmem_set_weight(self, _, host_ref, cli_id, value):
        node = XendNode.instance()
        try:
            node.tmem_set_weight(cli_id, value)
        except Exception, e:
            return xen_api_error(e)
        return xen_api_success_void()

    def host_tmem_set_cap(self, _, host_ref, cli_id, value):
        node = XendNode.instance()
        try:
            node.tmem_set_cap(cli_id, value)
        except Exception, e:
            return xen_api_error(e)
        return xen_api_success_void()

    def host_tmem_set_compress(self, _, host_ref, cli_id, value):
        node = XendNode.instance()
        try:
            node.tmem_set_compress(cli_id, value)
        except Exception, e:
            return xen_api_error(e)
        return xen_api_success_void()

    def host_tmem_query_freeable_mb(self, _, host_ref):
        node = XendNode.instance()
        try:
            pages = node.tmem_query_freeable_mb()
        except Exception, e:
            return xen_api_error(e)
        return xen_api_success(pages is None and -1 or pages)

    def host_tmem_shared_auth(self, _, host_ref, cli_id, uuid_str, auth):
        node = XendNode.instance()
        try:
            node.tmem_shared_auth(cli_id, uuid_str, auth)
        except Exception, e:
            return xen_api_error(e)
        return xen_api_success_void()

    # class methods
    def host_get_all(self, session):
        return xen_api_success((XendNode.instance().uuid,))
    def host_get_by_name_label(self, session, name):
        if XendNode.instance().name == name:
            return xen_api_success((XendNode.instance().uuid,))
        return xen_api_success([])
    
    def host_list_methods(self, _):
        def _funcs():
            return [getattr(XendAPI, x) for x in XendAPI.__dict__]

        return xen_api_success([x.api for x in _funcs()
                                if hasattr(x, 'api')])

    # Xen API: Class host_CPU
    # ----------------------------------------------------------------

    host_cpu_attr_ro = ['host',
                        'number',
                        'vendor',
                        'speed',
                        'modelname',
                        'stepping',
                        'flags',
                        'utilisation',
                        'features',
                        'cpu_pool']

    host_cpu_funcs  = [('get_unassigned_cpus', 'Set(host_cpu)')]

    # attributes
    def _host_cpu_get(self, ref, field):
        return xen_api_success(
            XendNode.instance().get_host_cpu_field(ref, field))

    def host_cpu_get_host(self, _, ref):
        return xen_api_success(XendNode.instance().uuid)
    def host_cpu_get_features(self, _, ref):
        return self._host_cpu_get(ref, 'features')
    def host_cpu_get_number(self, _, ref):
        return self._host_cpu_get(ref, 'number')
    def host_cpu_get_vendor(self, _, ref):
        return self._host_cpu_get(ref, 'vendor')
    def host_cpu_get_speed(self, _, ref):
        return self._host_cpu_get(ref, 'speed')
    def host_cpu_get_modelname(self, _, ref):
        return self._host_cpu_get(ref, 'modelname')
    def host_cpu_get_stepping(self, _, ref):
        return self._host_cpu_get(ref, 'stepping')
    def host_cpu_get_flags(self, _, ref):
        return self._host_cpu_get(ref, 'flags')
    def host_cpu_get_utilisation(self, _, ref):
        return xen_api_success(XendNode.instance().get_host_cpu_load(ref))
    def host_cpu_get_cpu_pool(self, _, ref):
        return xen_api_success(XendCPUPool.get_cpu_pool_by_cpu_ref(ref))

    # object methods
    def host_cpu_get_record(self, _, ref):
        node = XendNode.instance()
        record = dict([(f, node.get_host_cpu_field(ref, f))
                       for f in self.host_cpu_attr_ro
                       if f not in ['uuid', 'host', 'utilisation', 'cpu_pool']])
        record['uuid'] = ref
        record['host'] = node.uuid
        record['utilisation'] = node.get_host_cpu_load(ref)
        record['cpu_pool'] = XendCPUPool.get_cpu_pool_by_cpu_ref(ref)
        return xen_api_success(record)

    # class methods
    def host_cpu_get_all(self, session):
        return xen_api_success(XendNode.instance().get_host_cpu_refs())
    def host_cpu_get_unassigned_cpus(self, session):
        return xen_api_success(
            [ref for ref in XendNode.instance().get_host_cpu_refs()
                 if len(XendCPUPool.get_cpu_pool_by_cpu_ref(ref)) == 0])


    # Xen API: Class host_metrics
    # ----------------------------------------------------------------

    host_metrics_attr_ro = ['memory_total',
                            'memory_free',
                            'last_updated']
    host_metrics_attr_rw = []
    host_metrics_methods = []

    def host_metrics_get_all(self, _):
        return xen_api_success([XendNode.instance().host_metrics_uuid])

    def _host_metrics_get(self, ref, f):
        return xen_api_success(getattr(node, f)())

    def host_metrics_get_record(self, _, ref):
        return xen_api_success({
            'uuid'         : ref,
            'memory_total' : self._host_metrics_get_memory_total(),
            'memory_free'  : self._host_metrics_get_memory_free(),
            'last_updated' : now(),
            })

    def host_metrics_get_memory_total(self, _1, _2):
        return xen_api_success(self._host_metrics_get_memory_total())

    def host_metrics_get_memory_free(self, _1, _2):
        return xen_api_success(self._host_metrics_get_memory_free())

    def host_metrics_get_last_updated(self, _1, _2):
        return xen_api_success(now())

    def _host_metrics_get_memory_total(self):
        node = XendNode.instance()
        return node.xc.physinfo()['total_memory'] * 1024

    def _host_metrics_get_memory_free(self):
        node = XendNode.instance()
        return node.xc.physinfo()['free_memory'] * 1024

    # Xen API: Class VM
    # ----------------------------------------------------------------        

    VM_attr_ro = ['power_state',
                  'resident_on',
                  'consoles',
                  'VIFs',
                  'VBDs',
                  'DPCIs',
                  'DSCSIs',
                  'DSCSI_HBAs',
                  'tools_version',
                  'domid',
                  'is_control_domain',
                  'metrics',
                  'crash_dumps',
                  'cpu_pool',
                  ]
                  
    VM_attr_rw = ['name_label',
                  'name_description',
                  'user_version',
                  'is_a_template',
                  'auto_power_on',
                  'memory_dynamic_max',
                  'memory_dynamic_min',
                  'memory_static_max',
                  'memory_static_min',
                  'VCPUs_max',
                  'VCPUs_at_startup',
                  'VCPUs_params',
                  'actions_after_shutdown',
                  'actions_after_reboot',
                  'actions_after_suspend',
                  'actions_after_crash',
                  'PV_bootloader',
                  'PV_kernel',
                  'PV_ramdisk',
                  'PV_args',
                  'PV_bootloader_args',
                  'HVM_boot_policy',
                  'HVM_boot_params',
                  'platform',
                  'PCI_bus',
                  'other_config',
                  'security_label',
                  'pool_name',
                  ]

    VM_methods = [('clone', 'VM'),
                  ('start', None),
                  ('pause', None),
                  ('unpause', None),
                  ('clean_shutdown', None),
                  ('clean_reboot', None),
                  ('hard_shutdown', None),
                  ('hard_reboot', None),
                  ('suspend', None),
                  ('resume', None),
                  ('send_sysrq', None),
                  ('set_VCPUs_number_live', None),
                  ('add_to_HVM_boot_params', None),
                  ('remove_from_HVM_boot_params', None),
                  ('add_to_VCPUs_params', None),
                  ('add_to_VCPUs_params_live', None),
                  ('remove_from_VCPUs_params', None),
                  ('add_to_platform', None),
                  ('remove_from_platform', None),
                  ('add_to_other_config', None),
                  ('remove_from_other_config', None),
                  ('save', None),
                  ('set_memory_dynamic_max_live', None),
                  ('set_memory_dynamic_min_live', None),
                  ('send_trigger', None),
                  ('migrate', None),
                  ('destroy', None),
                  ('cpu_pool_migrate', None),
                  ]
    
    VM_funcs  = [('create', 'VM'),
                 ('restore', None),
                 ('get_by_name_label', 'Set(VM)')]

    # parameters required for _create()
    VM_attr_inst = [
        'name_label',
        'name_description',
        'user_version',
        'is_a_template',
        'memory_static_max',
        'memory_dynamic_max',
        'memory_dynamic_min',
        'memory_static_min',
        'VCPUs_max',
        'VCPUs_at_startup',
        'VCPUs_params',
        'actions_after_shutdown',
        'actions_after_reboot',
        'actions_after_suspend',
        'actions_after_crash',
        'PV_bootloader',
        'PV_kernel',
        'PV_ramdisk',
        'PV_args',
        'PV_bootloader_args',
        'HVM_boot_policy',
        'HVM_boot_params',
        'platform',
        'PCI_bus',
        'other_config',
        'security_label']
        
    def VM_get(self, name, session, vm_ref):
        return xen_api_success(
            XendDomain.instance().get_vm_by_uuid(vm_ref).info[name])

    def VM_set(self, name, session, vm_ref, value):
        xd = XendDomain.instance()
        dominfo = xd.get_vm_by_uuid(vm_ref)
        dominfo.info[name] = value
        return self._VM_save(dominfo)

    def _VM_save(self, dominfo):
        XendDomain.instance().managed_config_save(dominfo)
        return xen_api_success_void()

    # attributes (ro)
    def VM_get_power_state(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_power_state())
    
    def VM_get_resident_on(self, session, vm_ref):
        return xen_api_success(XendNode.instance().uuid)
       
    def VM_get_memory_static_max(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_memory_static_max())
    
    def VM_get_memory_static_min(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_memory_static_min())
    
    def VM_get_VIFs(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_vifs())
    
    def VM_get_VBDs(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_vbds())
    
    def VM_get_consoles(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_consoles())

    def VM_get_DPCIs(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_dpcis())
    
    def VM_get_DSCSIs(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_dscsis())

    def VM_get_DSCSI_HBAs(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_dscsi_HBAs())

    def VM_get_tools_version(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return dom.get_tools_version()

    def VM_get_metrics(self, _, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_metrics())

    def VM_get_VCPUs_max(self, _, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_todo()

    def VM_get_VCPUs_at_startup(self, _, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_todo()

    # attributes (rw)
    def VM_get_name_label(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.getName())
    
    def VM_get_name_description(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_todo()
    
    def VM_get_user_version(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_todo()
    
    def VM_get_is_a_template(self, session, ref):
        return self.VM_get('is_a_template', session, ref)
    
    def VM_get_auto_power_on(self, session, vm_ref):
        return self.VM_get('auto_power_on', session, vm_ref)
    
    def VM_get_memory_dynamic_max(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_memory_dynamic_max())

    def VM_get_memory_dynamic_min(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_memory_dynamic_min())
    
    def VM_get_VCPUs_params(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_vcpus_params())
    
    def VM_get_actions_after_shutdown(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_on_shutdown())
    
    def VM_get_actions_after_reboot(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_on_reboot())
    
    def VM_get_actions_after_suspend(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_on_suspend())        
    
    def VM_get_actions_after_crash(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_on_crash())
    
    def VM_get_PV_bootloader(self, session, vm_ref):
        return self.VM_get('PV_bootloader', session, vm_ref)
    
    def VM_get_PV_kernel(self, session, vm_ref):
        return self.VM_get('PV_kernel', session, vm_ref)
    
    def VM_get_PV_ramdisk(self, session, vm_ref):
        return self.VM_get('PV_ramdisk', session, vm_ref)
    
    def VM_get_PV_args(self, session, vm_ref):
        return self.VM_get('PV_args', session, vm_ref)

    def VM_get_PV_bootloader_args(self, session, vm_ref):
        return self.VM_get('PV_bootloader_args', session, vm_ref)

    def VM_get_HVM_boot_policy(self, session, vm_ref):
        return self.VM_get('HVM_boot_policy', session, vm_ref)
    
    def VM_get_HVM_boot_params(self, session, vm_ref):
        return self.VM_get('HVM_boot_params', session, vm_ref)
    
    def VM_get_platform(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_success(dom.get_platform())
    
    def VM_get_PCI_bus(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return dom.get_pci_bus()
    
    def VM_set_PCI_bus(self, session, vm_ref, val):
        return self.VM_set('PCI_bus', session, vm_ref, val)
    
    def VM_get_other_config(self, session, vm_ref):
        return self.VM_get('other_config', session, vm_ref)        

    def VM_get_domid(self, _, ref):
        domid = XendDomain.instance().get_vm_by_uuid(ref).getDomid()
        return xen_api_success(domid is None and -1 or domid)

    def VM_get_is_control_domain(self, session, vm_ref):
        xd = XendDomain.instance()
        return xen_api_success(
            xd.get_vm_by_uuid(vm_ref) == xd.privilegedDomain())

    def VM_get_cpu_pool(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        pool_ref = XendCPUPool.query_pool_ref(dom.get_cpu_pool())
        return xen_api_success(pool_ref)

    def VM_get_pool_name(self, session, vm_ref):
        return self.VM_get('pool_name', session, vm_ref)

    def VM_set_pool_name(self, session, vm_ref, value):
        return self.VM_set('pool_name', session, vm_ref, value)

    def VM_set_name_label(self, session, vm_ref, label):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        dom.setName(label)
        return self._VM_save(dom)
    
    def VM_set_name_description(self, session, vm_ref, desc):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_todo()
    
    def VM_set_user_version(self, session, vm_ref, ver):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_todo()
    
    def VM_set_is_a_template(self, session, vm_ref, is_template):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        return xen_api_todo()
    
    def VM_set_auto_power_on(self, session, vm_ref, val):
        return self.VM_set('auto_power_on', session, vm_ref, val)
    
    def VM_set_memory_dynamic_max(self, session, vm_ref, mem):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        dom.set_memory_dynamic_max(int(mem))
        return self._VM_save(dom)

    def VM_set_memory_dynamic_min(self, session, vm_ref, mem):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        dom.set_memory_dynamic_min(int(mem))
        return self._VM_save(dom)

    def VM_set_memory_static_max(self, session, vm_ref, mem):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        dom.set_memory_static_max(int(mem))
        return self._VM_save(dom)
    
    def VM_set_memory_static_min(self, session, vm_ref, mem):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        dom.set_memory_static_min(int(mem))
        return self._VM_save(dom)

    def VM_set_memory_dynamic_max_live(self, session, vm_ref, mem):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        dom.set_memory_dynamic_max(int(mem))
        # need to pass target as MiB
        dom.setMemoryTarget(int(mem)/1024/1024)
        return xen_api_success_void()

    def VM_set_memory_dynamic_min_live(self, session, vm_ref, mem):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        dom.set_memory_dynamic_min(int(mem))
        # need to pass target as MiB
        dom.setMemoryTarget(int(mem)/1024/1024)
        return xen_api_success_void()

    def VM_set_VCPUs_params(self, session, vm_ref, value):
        return self.VM_set('vcpus_params', session, vm_ref, value)

    def VM_add_to_VCPUs_params(self, session, vm_ref, key, value):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        if 'vcpus_params' not in dom.info:
            dom.info['vcpus_params'] = {}
        dom.info['vcpus_params'][key] = value
        return self._VM_save(dom)

    def VM_add_to_VCPUs_params_live(self, session, vm_ref, key, value):
        self.VM_add_to_VCPUs_params(session, vm_ref, key, value)
        self._VM_VCPUs_params_refresh(vm_ref)
        return xen_api_success_void()

    def _VM_VCPUs_params_refresh(self, vm_ref):
        xendom  = XendDomain.instance()
        xeninfo = xendom.get_vm_by_uuid(vm_ref)

        #update the cpumaps
        for key, value in xeninfo.info['vcpus_params'].items():
            if key.startswith("cpumap"):
                vcpu = int(key[6:])
                try:
                    cpus = map(int, value.split(","))
                    xendom.domain_pincpu(xeninfo.getDomid(), vcpu, cpus)
                except Exception, ex:
                    log.exception(ex)

        #need to update sched params aswell
        if 'weight' in xeninfo.info['vcpus_params'] \
           and 'cap' in xeninfo.info['vcpus_params']:
            weight = xeninfo.info['vcpus_params']['weight']
            xendom.domain_sched_credit2_set(xeninfo.getDomid(), weight)

    def VM_set_VCPUs_number_live(self, _, vm_ref, num):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        dom.setVCpuCount(int(num))
        return xen_api_success_void()
     
    def VM_remove_from_VCPUs_params(self, session, vm_ref, key):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        if 'vcpus_params' in dom.info \
               and key in dom.info['vcpus_params']:
            del dom.info['vcpus_params'][key]
            return self._VM_save(dom)
        else:
            return xen_api_success_void()
    
    def VM_set_VCPUs_at_startup(self, session, vm_ref, num):
        return self.VM_set('VCPUs_at_startup', session, vm_ref, num)

    def VM_set_VCPUs_max(self, session, vm_ref, num):
        return self.VM_set('VCPUs_max', session, vm_ref, num)

    def VM_set_actions_after_shutdown(self, session, vm_ref, action):
        if action not in XEN_API_ON_NORMAL_EXIT:
            return xen_api_error(['VM_ON_NORMAL_EXIT_INVALID', vm_ref])
        return self.VM_set('actions_after_shutdown', session, vm_ref, action)
    
    def VM_set_actions_after_reboot(self, session, vm_ref, action):
        if action not in XEN_API_ON_NORMAL_EXIT:
            return xen_api_error(['VM_ON_NORMAL_EXIT_INVALID', vm_ref])
        return self.VM_set('actions_after_reboot', session, vm_ref, action)
    
    def VM_set_actions_after_suspend(self, session, vm_ref, action):
        if action not in XEN_API_ON_NORMAL_EXIT:
            return xen_api_error(['VM_ON_NORMAL_EXIT_INVALID', vm_ref])
        return self.VM_set('actions_after_suspend', session, vm_ref, action)
    
    def VM_set_actions_after_crash(self, session, vm_ref, action):
        if action not in XEN_API_ON_CRASH_BEHAVIOUR:
            return xen_api_error(['VM_ON_CRASH_BEHAVIOUR_INVALID', vm_ref])
        return self.VM_set('actions_after_crash', session, vm_ref,
                XEN_API_ON_CRASH_BEHAVIOUR_LEGACY[action])

    def VM_set_HVM_boot_policy(self, session, vm_ref, value):
        if value != "" and value != "BIOS order":
            return xen_api_error(
                ['VALUE_NOT_SUPPORTED', 'VM.HVM_boot_policy', value,
                 'Xend supports only the "BIOS order" boot policy.'])
        else:
            return self.VM_set('HVM_boot_policy', session, vm_ref, value)

    def VM_set_HVM_boot_params(self, session, vm_ref, value):
        return self.VM_set('HVM_boot_params', session, vm_ref, value)

    def VM_add_to_HVM_boot_params(self, session, vm_ref, key, value):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        if 'HVM_boot_params' not in dom.info:
            dom.info['HVM_boot_params'] = {}
        dom.info['HVM_boot_params'][key] = value
        return self._VM_save(dom)

    def VM_remove_from_HVM_boot_params(self, session, vm_ref, key):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        if 'HVM_boot_params' in dom.info \
               and key in dom.info['HVM_boot_params']:
            del dom.info['HVM_boot_params'][key]
            return self._VM_save(dom)
        else:
            return xen_api_success_void()

    def VM_set_PV_bootloader(self, session, vm_ref, value):
        return self.VM_set('PV_bootloader', session, vm_ref, value)

    def VM_set_PV_kernel(self, session, vm_ref, value):
        return self.VM_set('PV_kernel', session, vm_ref, value)

    def VM_set_PV_ramdisk(self, session, vm_ref, value):
        return self.VM_set('PV_ramdisk', session, vm_ref, value)

    def VM_set_PV_args(self, session, vm_ref, value):
        return self.VM_set('PV_args', session, vm_ref, value)

    def VM_set_PV_bootloader_args(self, session, vm_ref, value):
        return self.VM_set('PV_bootloader_args', session, vm_ref, value)

    def VM_set_platform(self, session, vm_ref, value):
        return self.VM_set('platform', session, vm_ref, value)
    
    def VM_add_to_platform(self, session, vm_ref, key, value):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        plat = dom.get_platform()
        plat[key] = value
        return self.VM_set_platform(session, vm_ref, plat)

    def VM_remove_from_platform(self, session, vm_ref, key):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        plat = dom.get_platform()
        if key in plat:
            del plat[key]
            return self.VM_set_platform(session, vm_ref, plat)
        else:
            return xen_api_success_void()

    def VM_set_other_config(self, session, vm_ref, value):
        return self.VM_set('other_config', session, vm_ref, value)

    def VM_add_to_other_config(self, session, vm_ref, key, value):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        if dom and 'other_config' in dom.info:
            dom.info['other_config'][key] = value
        return self._VM_save(dom)

    def VM_remove_from_other_config(self, session, vm_ref, key):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        if dom and 'other_config' in dom.info \
               and key in dom.info['other_config']:
            del dom.info['other_config'][key]
            return self._VM_save(dom)
        else:
            return xen_api_success_void()

    def VM_get_crash_dumps(self, _, vm_ref):
        return xen_api_todo()

    # class methods
    def VM_get_all(self, session):
        refs = [d.get_uuid() for d in XendDomain.instance().list('all')]
        return xen_api_success(refs)
    
    def VM_get_by_name_label(self, session, label):
        xendom = XendDomain.instance()
        dom = xendom.domain_lookup_nr(label)
        if dom:
            return xen_api_success([dom.get_uuid()])
        return xen_api_success([])

    def VM_get_security_label(self, session, vm_ref):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        label = dom.get_security_label()
        return xen_api_success(label)

    def VM_set_security_label(self, session, vm_ref, sec_label, old_label):
        dom = XendDomain.instance().get_vm_by_uuid(vm_ref)
        (rc, errors, oldlabel, new_ssidref) = \
                                 dom.set_security_label(sec_label, old_label)
        if rc != xsconstants.XSERR_SUCCESS:
            return xen_api_error(['SECURITY_ERROR', rc,
                                 xsconstants.xserr2string(-rc)])
        if rc == 0:
            rc = new_ssidref
        return xen_api_success(rc)

    def VM_create(self, session, vm_struct):
        xendom = XendDomain.instance()
        domuuid = XendTask.log_progress(0, 100,
                                        xendom.create_domain, vm_struct)
        return xen_api_success(domuuid)
    
    # object methods
    def VM_get_record(self, session, vm_ref):
        xendom = XendDomain.instance()
        xeninfo = xendom.get_vm_by_uuid(vm_ref)
        if not xeninfo:
            return xen_api_error(['HANDLE_INVALID', 'VM', vm_ref])

        domid = xeninfo.getDomid()

        record = {
            'uuid': xeninfo.get_uuid(),
            'power_state': xeninfo.get_power_state(),
            'name_label': xeninfo.getName(),
            'name_description': xeninfo.getName(),
            'user_version': 1,
            'is_a_template': xeninfo.info['is_a_template'],
            'auto_power_on': xeninfo.info['auto_power_on'],
            'resident_on': XendNode.instance().uuid,
            'memory_static_min': xeninfo.get_memory_static_min(),
            'memory_static_max': xeninfo.get_memory_static_max(),
            'memory_dynamic_min': xeninfo.get_memory_dynamic_min(),
            'memory_dynamic_max': xeninfo.get_memory_dynamic_max(),
            'VCPUs_params': xeninfo.get_vcpus_params(),
            'VCPUs_at_startup': xeninfo.getVCpuCount(),
            'VCPUs_max': xeninfo.getVCpuCount(),
            'actions_after_shutdown': xeninfo.get_on_shutdown(),
            'actions_after_reboot': xeninfo.get_on_reboot(),
            'actions_after_suspend': xeninfo.get_on_suspend(),
            'actions_after_crash': xeninfo.get_on_crash(),
            'consoles': xeninfo.get_consoles(),
            'VIFs': xeninfo.get_vifs(),
            'VBDs': xeninfo.get_vbds(),
            'DPCIs': xeninfo.get_dpcis(),
            'DSCSIs': xeninfo.get_dscsis(),
            'DSCSI_HBAs': xeninfo.get_dscsi_HBAs(),
            'PV_bootloader': xeninfo.info.get('PV_bootloader'),
            'PV_kernel': xeninfo.info.get('PV_kernel'),
            'PV_ramdisk': xeninfo.info.get('PV_ramdisk'),
            'PV_args': xeninfo.info.get('PV_args'),
            'PV_bootloader_args': xeninfo.info.get('PV_bootloader_args'),
            'HVM_boot_policy': xeninfo.info.get('HVM_boot_policy'),
            'HVM_boot_params': xeninfo.info.get('HVM_boot_params'),
            'platform': xeninfo.get_platform(),
            'PCI_bus': xeninfo.get_pci_bus(),
            'tools_version': xeninfo.get_tools_version(),
            'other_config': xeninfo.info.get('other_config', {}),
            'domid': domid is None and -1 or domid,
            'is_control_domain': xeninfo.info['is_control_domain'],
            'metrics': xeninfo.get_metrics(),
            'security_label': xeninfo.get_security_label(),
            'crash_dumps': [],
            'pool_name': xeninfo.info.get('pool_name'),
            'cpu_pool' : XendCPUPool.query_pool_ref(xeninfo.get_cpu_pool()),
        }
        return xen_api_success(record)

    def VM_clean_reboot(self, session, vm_ref):
        xendom = XendDomain.instance()
        xeninfo = xendom.get_vm_by_uuid(vm_ref)
        XendTask.log_progress(0, 100, xeninfo.shutdown, "reboot")
        return xen_api_success_void()
    
    def VM_clean_shutdown(self, session, vm_ref):
        xendom = XendDomain.instance()
        xeninfo = xendom.get_vm_by_uuid(vm_ref)
        XendTask.log_progress(0, 100, xeninfo.shutdown, "poweroff")        
        return xen_api_success_void()
    
    def VM_clone(self, session, vm_ref):
        return xen_api_error(XEND_ERROR_UNSUPPORTED)
    
    def VM_destroy(self, session, vm_ref):
        return XendTask.log_progress(0, 100, do_vm_func,
                                     "domain_delete", vm_ref)
    
    def VM_hard_reboot(self, session, vm_ref):
        return XendTask.log_progress(0, 100, do_vm_func,
                                     "domain_reset", vm_ref)
    
    def VM_hard_shutdown(self, session, vm_ref):
        return XendTask.log_progress(0, 100, do_vm_func,
                                     "domain_destroy", vm_ref)
    
    def VM_pause(self, session, vm_ref):
        return XendTask.log_progress(0, 100, do_vm_func,
                                     "domain_pause", vm_ref)
    
    def VM_resume(self, session, vm_ref, start_paused):
        return XendTask.log_progress(0, 100, do_vm_func,
                                     "domain_resume", vm_ref,
                                     start_paused = start_paused)
    
    def VM_start(self, session, vm_ref, start_paused):
        try:
            return XendTask.log_progress(0, 100, do_vm_func,
                                         "domain_start", vm_ref,
                                         start_paused = start_paused)
        except HVMRequired, exn:
            return xen_api_error(['VM_HVM_REQUIRED', vm_ref])

    def VM_suspend(self, session, vm_ref):
        return XendTask.log_progress(0, 100, do_vm_func,
                                     "domain_suspend", vm_ref)
    
    def VM_unpause(self, session, vm_ref):
        return XendTask.log_progress(0, 100, do_vm_func,
                                     "domain_unpause", vm_ref)

    def VM_send_sysrq(self, _, vm_ref, req):
        xeninfo = XendDomain.instance().get_vm_by_uuid(vm_ref)
        if xeninfo.state == XEN_API_VM_POWER_STATE_RUNNING \
               or xeninfo.state == XEN_API_VM_POWER_STATE_PAUSED:
            xeninfo.send_sysrq(req)
            return xen_api_success_void()
        else:
            return xen_api_error(
                ['VM_BAD_POWER_STATE', vm_ref,
                 XendDomain.POWER_STATE_NAMES[XEN_API_VM_POWER_STATE_RUNNING],
                 XendDomain.POWER_STATE_NAMES[xeninfo.state]])

    def VM_send_trigger(self, _, vm_ref, trigger, vcpu):
        xendom = XendDomain.instance()
        xeninfo = xendom.get_vm_by_uuid(vm_ref)
        xendom.domain_send_trigger(xeninfo.getDomid(), trigger, vcpu)
        return xen_api_success_void()

    def VM_migrate(self, _, vm_ref, destination_url, live, other_config):
        xendom = XendDomain.instance()
        xeninfo = xendom.get_vm_by_uuid(vm_ref)

        port = other_config.get("port", 0)
        node = other_config.get("node", -1)
        ssl = other_config.get("ssl", None)
        chs = other_config.get("change_home_server", False)
        
        xendom.domain_migrate(xeninfo.getDomid(), destination_url,
                              bool(live), port, node, ssl, bool(chs))
        return xen_api_success_void()

    def VM_save(self, _, vm_ref, dest, checkpoint):
        xendom = XendDomain.instance()
        xeninfo = xendom.get_vm_by_uuid(vm_ref)
        xendom.domain_save(xeninfo.getDomid(), dest, checkpoint)
        return xen_api_success_void()

    def VM_restore(self, _, src, paused):
        xendom = XendDomain.instance()
        xendom.domain_restore(src, bool(paused))
        return xen_api_success_void()

    def VM_cpu_pool_migrate(self, session, vm_ref, cpu_pool_ref):
        xendom = XendDomain.instance()
        xeninfo = xendom.get_vm_by_uuid(vm_ref)
        domid = xeninfo.getDomid()
        pool = XendAPIStore.get(cpu_pool_ref, XendCPUPool.getClass())
        if pool == None:
            return xen_api_error(['HANDLE_INVALID', 'cpu_pool', cpu_pool_ref])
        if domid is not None:
            if domid == 0:
                return xen_api_error(['OPERATION_NOT_ALLOWED',
                    'could not move Domain-0'])
            try:
                XendCPUPool.move_domain(cpu_pool_ref, domid)
            except Exception, ex:
                return xen_api_error(['INTERNAL_ERROR',
                    'could not move domain'])
        self.VM_set('pool_name', session, vm_ref, pool.get_name_label())
        return xen_api_success_void()


    # Xen API: Class VBD
    # ----------------------------------------------------------------

    VBD_attr_ro = ['VM',
                   'VDI',
                   'metrics',
                   'runtime_properties']
    VBD_attr_rw = ['device',
                   'bootable',
                   'mode',
                   'type']

    VBD_attr_inst = VBD_attr_rw

    VBD_methods = [('media_change', None), ('destroy', None)]
    VBD_funcs = [('create', 'VBD')]
    
    # object methods
    def VBD_get_record(self, session, vbd_ref):
        xendom = XendDomain.instance()
        vm = xendom.get_vm_with_dev_uuid('vbd', vbd_ref)
        if not vm:
            return xen_api_error(['HANDLE_INVALID', 'VBD', vbd_ref])
        cfg = vm.get_dev_xenapi_config('vbd', vbd_ref)
        if not cfg:
            return xen_api_error(['HANDLE_INVALID', 'VBD', vbd_ref])

        valid_vbd_keys = self.VBD_attr_ro + self.VBD_attr_rw + \
                         self.Base_attr_ro + self.Base_attr_rw

        return_cfg = {}
        for k in cfg.keys():
            if k in valid_vbd_keys:
                return_cfg[k] = cfg[k]

        return_cfg['metrics'] = vbd_ref
        return_cfg['runtime_properties'] = {} #todo

        return xen_api_success(return_cfg)

    def VBD_media_change(self, session, vbd_ref, new_vdi_ref):
        xendom = XendDomain.instance()
        xennode = XendNode.instance()

        vm = xendom.get_vm_with_dev_uuid('vbd', vbd_ref)
        if not vm:
            return xen_api_error(['HANDLE_INVALID', 'VBD', vbd_ref])
        cur_vbd_struct = vm.get_dev_xenapi_config('vbd', vbd_ref)
        if not cur_vbd_struct:
            return xen_api_error(['HANDLE_INVALID', 'VBD', vbd_ref])
        if cur_vbd_struct['type'] != XEN_API_VBD_TYPE[0]:   # Not CD
            return xen_api_error(['HANDLE_INVALID', 'VBD', vbd_ref])
        if cur_vbd_struct['mode'] != 'RO':   # Not read only
            return xen_api_error(['HANDLE_INVALID', 'VBD', vbd_ref])

        new_vdi = xennode.get_vdi_by_uuid(new_vdi_ref)
        if not new_vdi:
            return xen_api_error(['HANDLE_INVALID', 'VDI', new_vdi_ref])
        new_vdi_image = new_vdi.get_location()

        valid_vbd_keys = self.VBD_attr_ro + self.VBD_attr_rw + \
                         self.Base_attr_ro + self.Base_attr_rw

        new_vbd_struct = {}
        for k in cur_vbd_struct.keys():
            if k in valid_vbd_keys:
                new_vbd_struct[k] = cur_vbd_struct[k]
        new_vbd_struct['VDI'] = new_vdi_ref

        try:
            XendTask.log_progress(0, 100,
                                  vm.change_vdi_of_vbd,
                                  new_vbd_struct, new_vdi_image)
        except XendError, e:
            log.exception("Error in VBD_media_change")
            return xen_api_error(['INTERNAL_ERROR', str(e)]) 

        return xen_api_success_void()

    # class methods
    def VBD_create(self, session, vbd_struct):
        xendom = XendDomain.instance()
        xennode = XendNode.instance()
        
        if not xendom.is_valid_vm(vbd_struct['VM']):
            return xen_api_error(['HANDLE_INVALID', 'VM', vbd_struct['VM']])
        
        dom = xendom.get_vm_by_uuid(vbd_struct['VM'])
        vdi = xennode.get_vdi_by_uuid(vbd_struct['VDI'])
        if not vdi:
            return xen_api_error(['HANDLE_INVALID', 'VDI', vbd_struct['VDI']])

        # new VBD via VDI/SR
        vdi_image = vdi.get_location()

        try:
            vbd_ref = XendTask.log_progress(0, 100,
                                            dom.create_vbd,
                                            vbd_struct, vdi_image)
        except XendError, e:
            log.exception("Error in VBD_create")
            return xen_api_error(['INTERNAL_ERROR', str(e)]) 
            
        xendom.managed_config_save(dom)
        return xen_api_success(vbd_ref)


    def VBD_destroy(self, session, vbd_ref):
        xendom = XendDomain.instance()
        vm = xendom.get_vm_with_dev_uuid('vbd', vbd_ref)
        if not vm:
            return xen_api_error(['HANDLE_INVALID', 'VBD', vbd_ref])

        vdi_ref = XendDomain.instance()\
                  .get_dev_property_by_uuid('vbd', vbd_ref, "VDI")
        vdi = XendNode.instance().get_vdi_by_uuid(vdi_ref)

        XendTask.log_progress(0, 100, vm.destroy_vbd, vbd_ref)

        xendom.managed_config_save(vm)
        return xen_api_success_void()

    def _VBD_get(self, vbd_ref, prop):
        return xen_api_success(
            XendDomain.instance().get_dev_property_by_uuid(
            'vbd', vbd_ref, prop))

    # attributes (ro)
    def VBD_get_metrics(self, _, vbd_ref):
        return xen_api_success(vbd_ref)

    def VBD_get_runtime_properties(self, _, vbd_ref):
        xendom = XendDomain.instance()
        dominfo = xendom.get_vm_with_dev_uuid('vbd', vbd_ref)
        device = dominfo.get_dev_config_by_uuid('vbd', vbd_ref)

        try:
            devid = int(device['id'])
            device_sxps = dominfo.getDeviceSxprs('vbd')
            device_dicts  = [dict(device_sxp[1][0:]) for device_sxp in device_sxps]
            device_dict = [device_dict
                           for device_dict in device_dicts
                           if int(device_dict['virtual-device']) == devid][0]

            return xen_api_success(device_dict)
        except Exception, exn:
            log.exception(exn)
            return xen_api_success({})

    # attributes (rw)
    def VBD_get_VM(self, session, vbd_ref):
        return self._VBD_get(vbd_ref, 'VM')
    
    def VBD_get_VDI(self, session, vbd_ref):
        return self._VBD_get(vbd_ref, 'VDI')

    def VBD_get_device(self, session, vbd_ref):
        return self._VBD_get(vbd_ref, 'device')

    def VBD_get_bootable(self, session, vbd_ref):
        return self._VBD_get(vbd_ref, 'bootable')

    def VBD_get_mode(self, session, vbd_ref):
        return self._VBD_get(vbd_ref, 'mode')

    def VBD_get_type(self, session, vbd_ref):
        return self._VBD_get(vbd_ref, 'type')

    def VBD_set_bootable(self, session, vbd_ref, bootable):
        bootable = bool(bootable)
        xd = XendDomain.instance()
        vm = xd.get_vm_with_dev_uuid('vbd', vbd_ref)
        vm.set_dev_property('vbd', vbd_ref, 'bootable', int(bootable))
        xd.managed_config_save(vm)
        return xen_api_success_void()

    def VBD_set_mode(self, session, vbd_ref, mode):
        if mode == 'RW':
            mode = 'w'
        else:
            mode = 'r'
        xd = XendDomain.instance()
        vm = xd.get_vm_with_dev_uuid('vbd', vbd_ref)
        vm.set_dev_property('vbd', vbd_ref, 'mode', mode)
        xd.managed_config_save(vm)
        return xen_api_success_void()

    def VBD_get_all(self, session):
        xendom = XendDomain.instance()
        vbds = [d.get_vbds() for d in XendDomain.instance().list('all')]
        vbds = reduce(lambda x, y: x + y, vbds)
        return xen_api_success(vbds)


    # Xen API: Class VBD_metrics
    # ----------------------------------------------------------------

    VBD_metrics_attr_ro = ['io_read_kbs',
                           'io_write_kbs',
                           'last_updated']
    VBD_metrics_attr_rw = []
    VBD_metrics_methods = []

    def VBD_metrics_get_all(self, session):
        return self.VBD_get_all(session)

    def VBD_metrics_get_record(self, _, ref):
        vm = XendDomain.instance().get_vm_with_dev_uuid('vbd', ref)
        if not vm:
            return xen_api_error(['HANDLE_INVALID', 'VBD_metrics', ref])
        return xen_api_success(
            { 'io_read_kbs'  : vm.get_dev_property('vbd', ref, 'io_read_kbs'),
              'io_write_kbs' : vm.get_dev_property('vbd', ref, 'io_write_kbs'),
              'last_updated' : now()
            })

    def VBD_metrics_get_io_read_kbs(self, _, ref):
        return self._VBD_get(ref, 'io_read_kbs')
    
    def VBD_metrics_get_io_write_kbs(self, session, ref):
        return self._VBD_get(ref, 'io_write_kbs')

    def VBD_metrics_get_last_updated(self, _1, _2):
        return xen_api_success(now())


    # Xen API: Class VIF
    # ----------------------------------------------------------------

    VIF_attr_ro = ['network',
                   'VM',
                   'metrics',
                   'runtime_properties']
    VIF_attr_rw = ['device',
                   'MAC',
                   'MTU',
                   'security_label']

    VIF_attr_inst = VIF_attr_rw

    VIF_methods = [('destroy', None)]
    VIF_funcs = [('create', 'VIF')]

                 
    # object methods
    def VIF_get_record(self, session, vif_ref):
        xendom = XendDomain.instance()
        vm = xendom.get_vm_with_dev_uuid('vif', vif_ref)
        if not vm:
            return xen_api_error(['HANDLE_INVALID', 'VIF', vif_ref])
        cfg = vm.get_dev_xenapi_config('vif', vif_ref)
        if not cfg:
            return xen_api_error(['HANDLE_INVALID', 'VIF', vif_ref])
        
        valid_vif_keys = self.VIF_attr_ro + self.VIF_attr_rw + \
                         self.Base_attr_ro + self.Base_attr_rw

        return_cfg = {}
        for k in cfg.keys():
            if k in valid_vif_keys:
                return_cfg[k] = cfg[k]
            
        return_cfg['metrics'] = vif_ref

        return xen_api_success(return_cfg)

    # class methods
    def VIF_create(self, session, vif_struct):
        xendom = XendDomain.instance()
        if not xendom.is_valid_vm(vif_struct['VM']):
            return xen_api_error(['HANDLE_INVALID', 'VM', vif_struct['VM']])

        dom = xendom.get_vm_by_uuid(vif_struct['VM'])
        try:
            vif_ref = dom.create_vif(vif_struct)
            xendom.managed_config_save(dom)
            return xen_api_success(vif_ref)
        except XendError, exn:
            return xen_api_error(['INTERNAL_ERROR', str(exn)])
          
    def VIF_destroy(self, session, vif_ref):
        xendom = XendDomain.instance()
        vm = xendom.get_vm_with_dev_uuid('vif', vif_ref)
        if not vm:
            return xen_api_error(['HANDLE_INVALID', 'VIF', vif_ref])

        vm.destroy_vif(vif_ref)

        xendom.managed_config_save(vm)
        return xen_api_success_void()

    def _VIF_get(self, ref, prop):
        return xen_api_success(
            XendDomain.instance().get_dev_property_by_uuid('vif', ref, prop))

    # getters/setters
    def VIF_get_metrics(self, _, vif_ref):
        return xen_api_success(vif_ref)

    def VIF_get_VM(self, session, vif_ref):
        xendom = XendDomain.instance()
        vm = xendom.get_vm_with_dev_uuid('vif', vif_ref)
        return xen_api_success(vm.get_uuid())

    def VIF_get_MTU(self, session, vif_ref):
        return self._VIF_get(vif_ref, 'MTU')
    
    def VIF_get_MAC(self, session, vif_ref):
        return self._VIF_get(vif_ref, 'MAC')

    def VIF_get_device(self, session, vif_ref):
        return self._VIF_get(vif_ref, 'device')
 
    def VIF_get_network(self, session, vif_ref):
        return self._VIF_get(vif_ref, 'network')
 
    def VIF_get_all(self, session):
        xendom = XendDomain.instance()
        vifs = [d.get_vifs() for d in XendDomain.instance().list('all')]
        vifs = reduce(lambda x, y: x + y, vifs)
        return xen_api_success(vifs)

    def VIF_get_runtime_properties(self, _, vif_ref):
        xendom = XendDomain.instance()
        dominfo = xendom.get_vm_with_dev_uuid('vif', vif_ref)
        device = dominfo.get_dev_config_by_uuid('vif', vif_ref)
        
        try:
            devid = int(device['id'])
        
            device_sxps = dominfo.getDeviceSxprs('vif')
            device_dicts = [dict(device_sxp[1][1:])
                            for device_sxp in device_sxps]
            
            device_dict = [device_dict
                       for device_dict in device_dicts
                       if int(device_dict['handle']) == devid][0]
            
            return xen_api_success(device_dict)
        
        except Exception, exn:
            log.exception(exn)
            return xen_api_success({})

    def VIF_get_security_label(self, session, vif_ref):
        return self._VIF_get(vif_ref, 'security_label')

    def _VIF_set(self, ref, prop, val, old_val):
        return XendDomain.instance().set_dev_property_by_uuid(
                       'vif', ref, prop, val, old_val)

    def VIF_set_security_label(self, session, vif_ref, sec_lab, old_lab):
        xendom = XendDomain.instance()
        dom = xendom.get_vm_with_dev_uuid('vif', vif_ref)
        if not dom:
            return xen_api_error(['HANDLE_INVALID', 'VIF', vif_ref])

        if dom._stateGet() == XEN_API_VM_POWER_STATE_RUNNING:
            raise SecurityError(-xsconstants.XSERR_RESOURCE_IN_USE)

        rc = self._VIF_set(vif_ref, 'security_label', sec_lab, old_lab)
        if rc == False:
            raise SecurityError(-xsconstants.XSERR_BAD_LABEL)
        return xen_api_success(xsconstants.XSERR_SUCCESS)


    # Xen API: Class VIF_metrics
    # ----------------------------------------------------------------

    VIF_metrics_attr_ro = ['io_read_kbs',
                           'io_write_kbs',
                           'io_total_read_kbs',
                           'io_total_write_kbs',
                           'last_updated']
    VIF_metrics_attr_rw = []
    VIF_metrics_methods = []

    def VIF_metrics_get_all(self, session):
        return self.VIF_get_all(session)

    def VIF_metrics_get_record(self, _, ref):
        vm = XendDomain.instance().get_vm_with_dev_uuid('vif', ref)
        if not vm:
            return xen_api_error(['HANDLE_INVALID', 'VIF_metrics', ref])
        return xen_api_success(
            { 'io_read_kbs'  : vm.get_dev_property('vif', ref, 'io_read_kbs'),
              'io_write_kbs' : vm.get_dev_property('vif', ref, 'io_write_kbs'),
              'io_total_read_kbs'  : vm.get_dev_property('vif', ref, 'io_total_read_kbs'),
              'io_total_write_kbs' : vm.get_dev_property('vif', ref, 'io_total_write_kbs'),
              'last_updated' : now()
            })

    def VIF_metrics_get_io_read_kbs(self, _, ref):
        return self._VIF_get(ref, 'io_read_kbs')
    
    def VIF_metrics_get_io_write_kbs(self, session, ref):
        return self._VIF_get(ref, 'io_write_kbs')

    def VIF_metrics_get_io_total_read_kbs(self, _, ref):
        return self._VIF_get(ref, 'io_total_read_kbs')

    def VIF_metrics_get_io_total_write_kbs(self, session, ref):
        return self._VIF_get(ref, 'io_total_write_kbs')

    def VIF_metrics_get_last_updated(self, _1, _2):
        return xen_api_success(now())


    # Xen API: Class VDI
    # ----------------------------------------------------------------
    VDI_attr_ro = ['SR',
                   'VBDs',
                   'physical_utilisation',
                   'type']
    VDI_attr_rw = ['name_label',
                   'name_description',
                   'virtual_size',
                   'sharable',
                   'read_only',
                   'other_config',
                   'security_label']
    VDI_attr_inst = VDI_attr_ro + VDI_attr_rw

    VDI_methods = [('destroy', None)]
    VDI_funcs = [('create', 'VDI'),
                  ('get_by_name_label', 'Set(VDI)')]

    def _get_VDI(self, ref):
        return XendNode.instance().get_vdi_by_uuid(ref)
    
    def VDI_get_VBDs(self, session, vdi_ref):
        vdi = XendNode.instance().get_vdi_by_uuid(vdi_ref)
        return xen_api_success(vdi.getVBDs())
    
    def VDI_get_physical_utilisation(self, session, vdi_ref):
        return xen_api_success(self._get_VDI(vdi_ref).
                               get_physical_utilisation())              
    
    def VDI_get_type(self, session, vdi_ref):
        return xen_api_success(self._get_VDI(vdi_ref).type)
    
    def VDI_get_name_label(self, session, vdi_ref):
        return xen_api_success(self._get_VDI(vdi_ref).name_label)

    def VDI_get_name_description(self, session, vdi_ref):
        return xen_api_success(self._get_VDI(vdi_ref).name_description)

    def VDI_get_SR(self, session, vdi_ref):
        return xen_api_success(self._get_VDI(vdi_ref).sr_uuid)

    def VDI_get_virtual_size(self, session, vdi_ref):
        return xen_api_success(self._get_VDI(vdi_ref).virtual_size)

    def VDI_get_sharable(self, session, vdi_ref):
        return xen_api_success(self._get_VDI(vdi_ref).sharable)

    def VDI_get_read_only(self, session, vdi_ref):
        return xen_api_success(self._get_VDI(vdi_ref).read_only)        

    def VDI_set_name_label(self, session, vdi_ref, value):
        self._get_VDI(vdi_ref).name_label = value
        return xen_api_success_void()

    def VDI_set_name_description(self, session, vdi_ref, value):
        self._get_VDI(vdi_ref).name_description = value
        return xen_api_success_void()

    def VDI_set_virtual_size(self, session, vdi_ref, value):
        return xen_api_error(XEND_ERROR_UNSUPPORTED)

    def VDI_set_sharable(self, session, vdi_ref, value):
        self._get_VDI(vdi_ref).sharable = bool(value)
        return xen_api_success_void()
    
    def VDI_set_read_only(self, session, vdi_ref, value):
        self._get_VDI(vdi_ref).read_only = bool(value)
        return xen_api_success_void()

    def VDI_get_other_config(self, session, vdi_ref):
        return xen_api_success(
            self._get_VDI(vdi_ref).other_config)

    def VDI_set_other_config(self, session, vdi_ref, other_config):
        self._get_VDI(vdi_ref).other_config = other_config
        return xen_api_success_void()

    # Object Methods
    
    def VDI_destroy(self, session, vdi_ref):
        # check no VBDs attached
        image = XendNode.instance().get_vdi_by_uuid(vdi_ref)
        if image.getVBDs():
            raise VDIError("Cannot destroy VDI with VBDs attached",
                           image.name_label)

        sr = XendNode.instance().get_sr_containing_vdi(vdi_ref)
        sr.destroy_vdi(vdi_ref)
        return xen_api_success_void()

    def VDI_get_record(self, session, vdi_ref):
        image = XendNode.instance().get_vdi_by_uuid(vdi_ref)
        return xen_api_success({
            'uuid': vdi_ref,
            'name_label': image.name_label,
            'name_description': image.name_description,
            'SR': image.sr_uuid,
            'VBDs': image.getVBDs(),
            'virtual_size': image.virtual_size,
            'physical_utilisation': image.physical_utilisation,
            'type': image.type,
            'sharable': image.sharable,
            'read_only': image.read_only,
            'other_config': image.other_config,
            'security_label' : image.get_security_label()
            })

    # Class Functions    
    def VDI_create(self, session, vdi_struct):
        sr_ref = vdi_struct.get('SR')
        xennode = XendNode.instance()
        if not xennode.is_valid_sr(sr_ref):
            return xen_api_error(['HANDLE_INVALID', 'SR', sr_ref])

        vdi_uuid = xennode.srs[sr_ref].create_vdi(vdi_struct)
        return xen_api_success(vdi_uuid)

    def VDI_get_all(self, session):
        xennode = XendNode.instance()
        vdis = [sr.get_vdis() for sr in xennode.srs.values()]
        return xen_api_success(reduce(lambda x, y: x + y, vdis))
    
    def VDI_get_by_name_label(self, session, name):
        xennode = XendNode.instance()
        return xen_api_success(xennode.get_vdi_by_name_label(name))

    def VDI_set_security_label(self, session, vdi_ref, sec_lab, old_lab):
        vdi = XendNode.instance().get_vdi_by_uuid(vdi_ref)
        rc = vdi.set_security_label(sec_lab, old_lab)
        if rc < 0:
            return xen_api_error(['SECURITY_ERROR', rc,
                                 xsconstants.xserr2string(-rc)])
        return xen_api_success(rc)

    def VDI_get_security_label(self, session, vdi_ref):
        vdi = XendNode.instance().get_vdi_by_uuid(vdi_ref)
        return xen_api_success(vdi.get_security_label())

    # Xen API: Class console
    # ----------------------------------------------------------------


    console_attr_ro = ['location', 'protocol', 'VM']
    console_attr_rw = ['other_config']
    console_funcs = [('create', 'console')]
    
    def console_get_all(self, session):
        xendom = XendDomain.instance()
        cons = [d.get_consoles() for d in XendDomain.instance().list('all')]
        cons = reduce(lambda x, y: x + y, cons)
        return xen_api_success(cons)

    def console_get_location(self, session, console_ref):
        xendom = XendDomain.instance()
        return xen_api_success(xendom.get_dev_property_by_uuid('console',
                                                               console_ref,
                                                               'location'))

    def console_get_protocol(self, session, console_ref):
        xendom = XendDomain.instance()
        return xen_api_success(xendom.get_dev_property_by_uuid('console',
                                                               console_ref,
                                                               'protocol'))
    
    def console_get_VM(self, session, console_ref):
        xendom = XendDomain.instance()        
        vm = xendom.get_vm_with_dev_uuid('console', console_ref)
        return xen_api_success(vm.get_uuid())
    
    def console_get_other_config(self, session, console_ref):
        xendom = XendDomain.instance()        
        return xen_api_success(xendom.get_dev_property_by_uuid('console',
                                                               console_ref,
                                                               'other_config'))
    
    # object methods
    def console_get_record(self, session, console_ref):
        xendom = XendDomain.instance()
        vm = xendom.get_vm_with_dev_uuid('console', console_ref)
        if not vm:
            return xen_api_error(['HANDLE_INVALID', 'console', console_ref])
        cfg = vm.get_dev_xenapi_config('console', console_ref)
        if not cfg:
            return xen_api_error(['HANDLE_INVALID', 'console', console_ref])
        
        valid_console_keys = self.console_attr_ro + self.console_attr_rw + \
                             self.Base_attr_ro + self.Base_attr_rw

        return_cfg = {}
        for k in cfg.keys():
            if k in valid_console_keys:
                return_cfg[k] = cfg[k]
            
        return xen_api_success(return_cfg)

    def console_create(self, session, console_struct):
        xendom = XendDomain.instance()
        if not xendom.is_valid_vm(console_struct['VM']):
            return xen_api_error(['HANDLE_INVALID', 'VM',
                                  console_struct['VM']])
        
        dom = xendom.get_vm_by_uuid(console_struct['VM'])
        try:
            if 'protocol' not in console_struct:
                return xen_api_error(['CONSOLE_PROTOCOL_INVALID',
                                      'No protocol specified'])
            
            console_ref = dom.create_console(console_struct)
            xendom.managed_config_save(dom)
            return xen_api_success(console_ref)
        except XendError, exn:
            return xen_api_error(['INTERNAL_ERROR', str(exn)])

    def console_set_other_config(self, session, console_ref, other_config):
        xd = XendDomain.instance()
        vm = xd.get_vm_with_dev_uuid('console', console_ref)
        vm.set_console_other_config(console_ref, other_config)
        xd.managed_config_save(vm)
        return xen_api_success_void()

    # Xen API: Class SR
    # ----------------------------------------------------------------
    SR_attr_ro = ['VDIs',
                  'PBDs',
                  'virtual_allocation',
                  'physical_utilisation',
                  'physical_size',
                  'type',
                  'content_type']
    
    SR_attr_rw = ['name_label',
                  'name_description']
    
    SR_attr_inst = ['physical_size',
                    'type',
                    'name_label',
                    'name_description']
    
    SR_methods = []
    SR_funcs = [('get_by_name_label', 'Set(SR)'),
                ('get_by_uuid', 'SR')]

    # Class Functions
    def SR_get_all(self, session):
        return xen_api_success(XendNode.instance().get_all_sr_uuid())
  
    def SR_get_by_name_label(self, session, label):
        return xen_api_success(XendNode.instance().get_sr_by_name(label))
    
    def SR_get_supported_types(self, _):
        return xen_api_success(['local', 'qcow_file'])

    # Class Methods
    
    def SR_get_record(self, session, sr_ref):
        sr = XendNode.instance().get_sr(sr_ref)
        if sr:
            return xen_api_success(sr.get_record())
        return xen_api_error(['HANDLE_INVALID', 'SR', sr_ref])

    # Attribute acceess

    def _get_SR_func(self, sr_ref, func):
        return xen_api_success(getattr(XendNode.instance().get_sr(sr_ref),
                                       func)())

    def _get_SR_attr(self, sr_ref, attr):
        return xen_api_success(getattr(XendNode.instance().get_sr(sr_ref),
                                       attr))

    def SR_get_VDIs(self, _, ref):
        return self._get_SR_func(ref, 'list_images')

    def SR_get_PBDs(self, _, ref):
        return xen_api_success(XendPBD.get_by_SR(ref))

    def SR_get_virtual_allocation(self, _, ref):
        return self._get_SR_func(ref, 'virtual_allocation')

    def SR_get_physical_utilisation(self, _, ref):
        return self._get_SR_func(ref, 'physical_utilisation')

    def SR_get_physical_size(self, _, ref):
        return self._get_SR_attr(ref, 'physical_size')
    
    def SR_get_type(self, _, ref):
        return self._get_SR_attr(ref, 'type')

    def SR_get_content_type(self, _, ref):
        return self._get_SR_attr(ref, 'content_type')

    def SR_get_name_label(self, _, ref):
        return self._get_SR_attr(ref, 'name_label')
    
    def SR_get_name_description(self, _, ref):
        return self._get_SR_attr(ref, 'name_description')

    def SR_set_name_label(self, session, sr_ref, value):
        sr = XendNode.instance.get_sr(sr_ref)
        if sr:
            sr.name_label = value
            XendNode.instance().save()
        return xen_api_success_void()
    
    def SR_set_name_description(self, session, sr_ref, value):
        sr = XendNode.instance.get_sr(sr_ref)
        if sr:
            sr.name_description = value
            XendNode.instance().save()        
        return xen_api_success_void()


    # Xen API: Class event
    # ----------------------------------------------------------------

    event_attr_ro = []
    event_attr_rw = []
    event_funcs = [('register', None),
                   ('unregister', None),
                   ('next', None)]

    def event_register(self, session, reg_classes):
        event_register(session, reg_classes)
        return xen_api_success_void()

    def event_unregister(self, session, unreg_classes):
        event_unregister(session, unreg_classes)
        return xen_api_success_void()

    def event_next(self, session):
        return event_next(session)

    # Xen API: Class debug
    # ----------------------------------------------------------------

    debug_methods = [('destroy', None),
                     ('get_record', 'debug')]
    debug_funcs = [('wait', None),
                   ('return_failure', None)]
    
    def debug_wait(self, session, wait_secs):
         import time
         prog_units = 100/float(wait_secs)
         for i in range(int(wait_secs)):
             XendTask.log_progress(prog_units * i, prog_units * (i + 1),
                                   time.sleep, 1)
         return xen_api_success_void()


    def debug_return_failure(self, session):
        return xen_api_error(['DEBUG_FAIL', session])

    def debug_create(self, session):
        debug_uuid = genuuid.createString()
        self._debug[debug_uuid] = None
        return xen_api_success(debug_uuid)

    def debug_destroy(self, session, debug_ref):
        del self._debug[debug_ref]
        return xen_api_success_void()

    def debug_get_record(self, session, debug_ref):
        return xen_api_success({'uuid': debug_ref})


class XendAPIAsyncProxy:
    """ A redirector for Async.Class.function calls to XendAPI
    but wraps the call for use with the XendTaskManager.

    @ivar xenapi: Xen API instance
    @ivar method_map: Mapping from XMLRPC method name to callable objects.
    """

    method_prefix = 'Async.'

    def __init__(self, xenapi):
        """Initialises the Async Proxy by making a map of all
        implemented Xen API methods for use with XendTaskManager.

        @param xenapi: XendAPI instance
        """
        self.xenapi = xenapi
        self.method_map = {}
        for method_name in dir(self.xenapi):
            method = getattr(self.xenapi, method_name)            
            if method_name[0] != '_' and hasattr(method, 'async') \
                   and method.async == True:
                self.method_map[method.api] = method

    def _dispatch(self, method, args):
        """Overridden method so that SimpleXMLRPCServer will
        resolve methods through this method rather than through
        inspection.

        @param method: marshalled method name from XMLRPC.
        @param args: marshalled arguments from XMLRPC.
        """

        # Only deal with method names that start with "Async."
        if not method.startswith(self.method_prefix):
            return xen_api_error(['MESSAGE_METHOD_UNKNOWN', method])

        # Lookup synchronous version of the method
        synchronous_method_name = method[len(self.method_prefix):]
        if synchronous_method_name not in self.method_map:
            return xen_api_error(['MESSAGE_METHOD_UNKNOWN', method])
        
        method = self.method_map[synchronous_method_name]

        # Check that we've got enough arguments before issuing a task ID.
        needed = argcounts[method.api]
        if len(args) != needed:
            return xen_api_error(['MESSAGE_PARAMETER_COUNT_MISMATCH',
                                  self.method_prefix + method.api, needed,
                                  len(args)])

        # Validate the session before proceeding
        session = args[0]
        if not auth_manager().is_session_valid(session):
            return xen_api_error(['SESSION_INVALID', session])

        # create and execute the task, and return task_uuid
        return_type = getattr(method, 'return_type', None)
        task_uuid = XendTaskManager.create_task(method, args,
                                                synchronous_method_name,
                                                return_type,
                                                synchronous_method_name,
                                                session)
        return xen_api_success(task_uuid)