# Source code for aioxmpp.stream

    ########################################################################
    # File name: stream.py
    # This file is part of: aioxmpp
    #
    # LICENSE
    #
    # This program is free software: you can redistribute it and/or modify
    # it under the terms of the GNU Lesser General Public License as
    # published by the Free Software Foundation, either version 3 of the
    # License, or (at your option) any later version.
    #
    # This program 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 program.  If not, see
    # <http://www.gnu.org/licenses/>.
    #
    ########################################################################
    """
    :mod:`~aioxmpp.stream` --- Stanza stream
    ########################################

    The stanza stream is the layer of abstraction above the XML stream. It deals
    with sending and receiving stream-level elements, mainly stanzas. It also
    handles stream liveness and stream management.

    It provides ways to track stanzas on their way to the remote, as far as that is
    possible.

    .. _aioxmpp.stream.General Information:

    General information
    ===================

    .. _aioxmpp.stream.General Information.Timeouts:

    Timeouts / Stream Aliveness checks
    ----------------------------------

    The :class:`StanzaStream` relies on the :class:`XMLStream` dead time aliveness
    monitoring (see also :attr:`~.XMLStream.deadtime_soft_limit`) to detect a
    broken stream.

    The limits can be configured with the two attributes
    :attr:`~.StanzaStream.soft_timeout` and :attr:`~.StanzaStream.round_trip_time`.
    When :attr:`~.StanzaStream.soft_timeout` elapses after the last bit of data
    received from the server, the :class:`StanzaStream` issues a ping. The server
    then has one :attr:`~.StanzaStream.round_trip_time` worth of time to answer.
    If this does not happen, the :class:`XMLStream` will be terminated by the
    aliveness monitor and normal handling of a broken connection takes over.

    .. _aioxmpp.stream.General Information.Filters:

    Stanza Filters
    --------------

    Stanza filters allow to hook into the stanza sending/reception pipeline
    after/before the application sees the stanza.

    Inbound stanza filters
    ~~~~~~~~~~~~~~~~~~~~~~

    Inbound stanza filters allow to hook into the stanza processing by replacing,
    modifying or otherwise processing stanza contents *before* the usual handlers
    for that stanza are invoked. With inbound stanza filters, there are no
    restrictions as to what processing may take place on a stanza, as no one but
    the stream may have references to its contents.

    .. warning::

        Raising an exception from within a stanza filter kills the stream.

    Note that if a filter function drops an incoming stanza (by returning
    :data:`None`), it **must** ensure that the client still behaves RFC
    compliant. The inbound stanza filters are found here:

    * :attr:`~.StanzaStream.service_inbound_message_filter`
    * :attr:`~.StanzaStream.service_inbound_presence_filter`
    * :attr:`~.StanzaStream.app_inbound_message_filter`
    * :attr:`~.StanzaStream.app_inbound_presence_filter`

    Outbound stanza filters
    ~~~~~~~~~~~~~~~~~~~~~~~

    Outbound stanza filters work similar to inbound stanza filters, but due to
    their location in the processing chain and possible interactions with senders
    of stanzas, there are some things to consider:

    * Per convention, a outbound stanza filter **must not** modify any child
      elements which are already present in the stanza when it receives the
      stanza.

      It may however add new child elements or remove existing child elements,
      as well as copying and *then* modifying existing child elements.

    * If the stanza filter replaces the stanza, it is responsible for making
      sure that the new stanza has appropriate
      :attr:`~.stanza.StanzaBase.from_`, :attr:`~.stanza.StanzaBase.to` and
      :attr:`~.stanza.StanzaBase.id` values. There are no checks to enforce
      this, because errorr handling at this point is peculiar. The stanzas will
      be sent as-is.

    * Similar to inbound filters, it is the responsibility of the filters that
      if stanzas are dropped, the client still behaves RFC-compliant.

    Now that you have been warned, here are the attributes for accessing the
    outbound filter chains. These otherwise work exactly like their inbound
    counterparts, but service filters run *after* application filters on
    outbound processing.

    * :attr:`~.StanzaStream.service_outbound_message_filter`
    * :attr:`~.StanzaStream.service_outbound_presence_filter`
    * :attr:`~.StanzaStream.app_outbound_message_filter`
    * :attr:`~.StanzaStream.app_outbound_presence_filter`

    When to use stanza filters?
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~

    In general, applications will rarely need them. However, services may make
    profitable use of them, and it is a convenient way for them to inspect or
    modify incoming or outgoing stanzas before any normally registered handler
    processes them.

    In general, whenever you do something which *supplements* the use of the stanza
    with respect to the RFC but does not fulfill the orignial intent of the stanza,
    it is advisable to use a filter instead of a callback on the actual stanza.

    Vice versa, if you were to develop a service which manages presence
    subscriptions, it would be more correct to use
    :meth:`register_presence_callback`; this prevents other services which try
    to do the same from conflicting with you. You would then provide callbacks
    to the application to let it learn about presence subscriptions.

    Stanza Stream class
    ===================

    This section features the complete documentation of the (rather important and
    complex) :class:`StanzaStream`. Some more general information has been moved to
    the previous section (:ref:`aioxmpp.stream.General Information`) to make it
    easier to read and find.

    .. autoclass:: StanzaStream

    Context managers
    ================

    The following context managers can be used together with :class:`StanzaStream`
    instances and the filters available on them.

    .. autofunction:: iq_handler

    .. autofunction:: message_handler

    .. autofunction:: presence_handler

    .. autofunction:: stanza_filter

    Low-level stanza tracking
    =========================

    The following classes are used to track stanzas in the XML stream to the
    server. This is independent of things like :xep:`Message Delivery Receipts
    <0184>` (for which services are provided at :mod:`aioxmpp.tracking`); it
    only provides tracking to the remote server and even that only if stream
    management is used. Otherwise, it only provides tracking in the :mod:`aioxmpp`
    internal queues.

    .. autoclass:: StanzaToken

    .. autoclass:: StanzaState

    Filters
    =======

    The service-level filters used by the :class:`StanzaStream` use
    :class:`~.callbacks.Filter`. The application-level filters are using the
    following class:

    .. autoclass:: AppFilter

    Exceptions
    ==========

    .. autoclass:: DestructionRequested

    """

    import asyncio
    import contextlib
    import functools
    import logging
    import time
    import warnings

    from datetime import datetime, timedelta
    from enum import Enum

    from . import (
        stanza,
        stanza as stanza_,
        errors,
        custom_queue,
        nonza,
        callbacks,
        protocol,
        structs,
        ping,
    )

    from .utils import namespaces

    class AppFilter(callbacks.Filter):
        """
        A specialized :class:`Filter` version. The only difference is in the
        handling of the `order` argument to :meth:`register`:

        .. automethod:: register
        """

        def register(self, func, order=0):
            """
            This method works exactly like :meth:`Filter.register`, but `order` has
            a default value of ``0``.
            """
            return super().register(func, order)

    class PingEventType(Enum):
        SEND_OPPORTUNISTIC = 0
        SEND_NOW = 1
        TIMEOUT = 2

    class DestructionRequested(ConnectionError):
        """
        Subclass of :class:`ConnectionError` indicating that the destruction of the
        stream was requested by the user, directly or indirectly.
        """

    class StanzaState(Enum):
        """
        The various states an outgoing stanza can have.

        .. attribute:: ACTIVE

           The stanza has just been enqueued for sending and has not been taken
           care of by the StanzaStream yet.

        .. attribute:: SENT

           The stanza has been sent over a stream with Stream Management enabled,
           but not acked by the remote yet.

        .. attribute:: ACKED

           The stanza has been sent over a stream with Stream Management enabled
           and has been acked by the remote.

           This is a final state.

        .. attribute:: SENT_WITHOUT_SM

           The stanza has been sent over a stream without Stream Management enabled
           or has been sent over a stream with Stream Management enabled, but for
           which resumption has failed before the stanza has been acked.

           This is a final state.

        .. attribute:: ABORTED

           The stanza has been retracted before it left the active queue.

           This is a final state.

        .. attribute:: DROPPED

           The stanza has been dropped by one of the filters configured in the
           :class:`StanzaStream`.

           This is a final state.

        .. attribute:: DISCONNECTED

           The stream has been stopped (without SM) or closed before the stanza was
           sent.

           This is a final state.

        .. attribute:: FAILED

           It was attempted to send the stanza, but it failed to serialise to
           valid XML or another non-fatal transport error occured.

           This is a final state.

           .. versionadded:: 0.9

        """
        ACTIVE = 0
        SENT = 1
        ACKED = 2
        SENT_WITHOUT_SM = 3
        ABORTED = 4
        DROPPED = 5
        DISCONNECTED = 6
        FAILED = 7

    class StanzaErrorAwareListener:
        def __init__(self, forward_to):
            self._forward_to = forward_to

        def data(self, stanza_obj):
            if stanza_obj.type_.is_error:
                return self._forward_to.error(
                    stanza_obj.error.to_exception()
                )
            return self._forward_to.data(stanza_obj)

        def error(self, exc):
            return self._forward_to.error(exc)

        def is_valid(self):
            return self._forward_to.is_valid()

    class StanzaToken:
        """
        A token to follow the processing of a `stanza`.

        `on_state_change` may be a function which will be called with the token and
        the new :class:`StanzaState` whenever the state of the token changes.

        .. versionadded:: 0.8

           Stanza tokens are :term:`awaitable`.

        .. describe:: await token
        .. describe:: yield from token

           Wait until the stanza is either sent or failed to sent.

           .. warning::

              This only works with Python 3.5 or newer.

           :raises ConnectionError: if the stanza enters
                                    :attr:`~.StanzaState.DISCONNECTED` state.
           :raises RuntimeError: if the stanza enters :attr:`~.StanzaState.ABORTED`
                                 or :attr:`~.StanzaState.DROPPED` state.
           :raises Exception: re-raised if the stanza token fails to serialise or
                              another transient transport problem occurs.
           :return: :data:`None`

           If a coroutine awaiting a token is cancelled, the token is aborted. Use
           :func:`asyncio.shield` to prevent this.

           .. warning::

              This is no guarantee that the recipient received the stanza. Without
              stream management, it can not even guarenteed that the server has
              seen the stanza.

              This is primarily useful as a synchronisation primitive between the
              sending of a stanza and another stream operation, such as closing the
              stream.

        .. note::

           Exceptions sent to the stanza token (when it enters
           :attr:`StanzaState.FAILED`) are only available by awaiting the token,
           not via the callback.

        .. autoattribute:: state

        .. automethod:: abort
        """
        __slots__ = ("stanza", "_state", "on_state_change", "_sent_future",
                     "_state_exception")

        def __init__(self, stanza, *, on_state_change=None):
            self.stanza = stanza
            self._state = StanzaState.ACTIVE
            self._state_exception = None
            self._sent_future = None
            self.on_state_change = on_state_change

        @property
        def state(self):
            """
            The current :class:`StanzaState` of the token. Tokens are created with
            :attr:`StanzaState.ACTIVE`.
            """

            return self._state

        @property
        def future(self):
            if self._sent_future is None:
                self._sent_future = asyncio.Future()
                self._update_future()
            return self._sent_future

        def _update_future(self):
            if self._sent_future.done():
                return

            if self._state == StanzaState.DISCONNECTED:
                self._sent_future.set_exception(ConnectionError("disconnected"))
            elif self._state == StanzaState.DROPPED:
                self._sent_future.set_exception(
                    RuntimeError("stanza dropped by filter")
                )
            elif self._state == StanzaState.ABORTED:
                self._sent_future.set_exception(RuntimeError("stanza aborted"))
            elif self._state == StanzaState.FAILED:
                self._sent_future.set_exception(
                    self._state_exception or
                    ValueError("failed to send stanza for unknown local reasons")
                )
            elif     (self._state == StanzaState.SENT_WITHOUT_SM or
                      self._state == StanzaState.ACKED):
                self._sent_future.set_result(None)

        def _set_state(self, new_state, exception=None):
            self._state = new_state
            self._state_exception = exception
            if self.on_state_change is not None:
                self.on_state_change(self, new_state)

            if self._sent_future is not None:
                self._update_future()

        def abort(self):
            """
            Abort the stanza. Attempting to call this when the stanza is in any
            non-:class:`~StanzaState.ACTIVE`, non-:class:`~StanzaState.ABORTED`
            state results in a :class:`RuntimeError`.

            When a stanza is aborted, it will reside in the active queue of the
            stream, not will be sent and instead discarded silently.
            """
            if (self._state != StanzaState.ACTIVE and
                    self._state != StanzaState.ABORTED):
                raise RuntimeError("cannot abort stanza (already sent)")
            self._set_state(StanzaState.ABORTED)

        def __repr__(self):
            return "<StanzaToken id=0x{:016x}>".format(id(self))

        @asyncio.coroutine
        def __await__(self):
            try:
                yield from asyncio.shield(self.future)
            except asyncio.CancelledError:
                if self._state == StanzaState.ACTIVE:
                    self.abort()
                raise

        __iter__ = __await__

    class StanzaStream:
        """
        A stanza stream. This is the next layer of abstraction above the XMPP XML
        stream, which mostly deals with stanzas (but also with certain other
        stream-level elements, such as :xep:`0198` Stream Management Request/Acks).

        It is independent from a specific :class:`~aioxmpp.protocol.XMLStream`
        instance. A :class:`StanzaStream` can be started with one XML stream,
        stopped later and then resumed with another XML stream. The user of the
        :class:`StanzaStream` has to make sure that the XML streams are compatible,
        identity-wise (use the same JID).

        `local_jid` may be the **bare** sender JID associated with the stanza
        stream. This is required for compatibility with ejabberd. If it is omitted,
        communication with ejabberd instances may not work.

        `loop` may be used to explicitly specify the :class:`asyncio.BaseEventLoop`
        to use, otherwise the current event loop is used.

        `base_logger` can be used to explicitly specify a :class:`logging.Logger`
        instance to fork off the logger from. The :class:`StanzaStream` will use a
        child logger of `base_logger` called ``StanzaStream``.

        .. versionchanged:: 0.4

           The `local_jid` argument was added.

        .. versionchanged:: 0.10

            Ping handling was reworked.

        Starting/Stopping the stream:

        .. automethod:: start

        .. automethod:: stop

        .. automethod:: wait_stop

        .. automethod:: close

        .. autoattribute:: running

        .. automethod:: flush_incoming

        Timeout configuration (see
        :ref:`aioxmpp.stream.General Information.Timeouts`):

        .. autoattribute:: round_trip_time

        .. autoattribute:: soft_timeout

        Sending stanzas:

        .. deprecated:: 0.10

            Sending stanzas directly on the stream is deprecated. The methods
            have been moved to the client:

            .. autosummary::

                aioxmpp.Client.send
                aioxmpp.Client.enqueue

        .. automethod:: send

        .. automethod:: enqueue

        .. method:: enqueue_stanza

           Alias of :meth:`enqueue`.

           .. deprecated:: 0.8

              This alias is deprecated and will be removed in 1.0.

        .. automethod:: send_and_wait_for_sent

        .. automethod:: send_iq_and_wait_for_reply

        Receiving stanzas:

        .. automethod:: register_iq_request_handler

        .. automethod:: unregister_iq_request_handler

        .. automethod:: register_message_callback

        .. automethod:: unregister_message_callback

        .. automethod:: register_presence_callback

        .. automethod:: unregister_presence_callback

        Rarely used registries / deprecated aliases:

        .. automethod:: register_iq_request_coro

        .. automethod:: unregister_iq_request_coro

        .. automethod:: register_iq_response_future

        .. automethod:: register_iq_response_callback

        .. automethod:: unregister_iq_response

        Inbound Stanza Filters (see
        :ref:`aioxmpp.stream.General Information.Filters`):

        .. attribute:: app_inbound_presence_filter

           This is a :class:`AppFilter` based filter chain on inbound presence
           stanzas. It can be used to attach application-specific filters.

        .. attribute:: service_inbound_presence_filter

           This is another filter chain for inbound presence stanzas. It runs
           *before* the :attr:`app_inbound_presence_filter` chain and all functions
           registered there must have :class:`service.Service` *classes* as `order`
           value (see :meth:`Filter.register`).

           This filter chain is intended to be used by library services, such as a
           :xep:`115` implementation which may start a :xep:`30` lookup at the
           target entity to resolve the capability hash or prime the :xep:`30`
           cache with the service information obtained by interpreting the
           :xep:`115` hash value.

        .. attribute:: app_inbound_message_filter

           This is a :class:`AppFilter` based filter chain on inbound message
           stanzas. It can be used to attach application-specific filters.

        .. attribute:: service_inbound_message_filter

           This is the analogon of :attr:`service_inbound_presence_filter` for
           :attr:`app_inbound_message_filter`.

        Outbound Stanza Filters (see
        :ref:`aioxmpp.stream.General Information.Filters`):

        .. attribute:: app_outbound_presence_filter

           This is a :class:`AppFilter` based filter chain on outbound presence
           stanzas. It can be used to attach application-specific filters.

           Before using this attribute, make sure that you have read the notes
           above.

        .. attribute:: service_outbound_presence_filter

           This is the analogon of :attr:`service_inbound_presence_filter`, but for
           outbound presence. It runs *after* the
           :meth:`app_outbound_presence_filter`.

           Before using this attribute, make sure that you have read the notes
           above.

        .. attribute:: app_outbound_message_filter

           This is a :class:`AppFilter` based filter chain on inbound message
           stanzas. It can be used to attach application-specific filters.

           Before using this attribute, make sure that you have read the notes
           above.

        .. attribute:: service_outbound_messages_filter

           This is the analogon of :attr:`service_outbound_presence_filter`, but
           for outbound messages.

           Before using this attribute, make sure that you have read the notes
           above.

        Using stream management:

        .. automethod:: start_sm

        .. automethod:: resume_sm

        .. automethod:: stop_sm

        .. autoattribute:: sm_enabled

        Stream management state inspection:

        .. autoattribute:: sm_outbound_base

        .. autoattribute:: sm_inbound_ctr

        .. autoattribute:: sm_unacked_list

        .. autoattribute:: sm_id

        .. autoattribute:: sm_max

        .. autoattribute:: sm_location

        .. autoattribute:: sm_resumable

        Miscellaneous:

        .. autoattribute:: local_jid

        Signals:

        .. signal:: on_failure(exc)

           Emits when the stream has failed, i.e. entered stopped state without
           request by the user.

           :param exc: The exception which caused the stream to fail.
           :type exc: :class:`Exception`

           A failure occurs whenever the main task of the :class:`StanzaStream`
           (the one started by :meth:`start`) terminates with an exception.

           Examples are :class:`ConnectionError` as raised upon a ping timeout and
           any exceptions which may be raised by the
           :meth:`aioxmpp.protocol.XMLStream.send_xso` method.

           Before :meth:`on_failure` is emitted, the :class:`~.protocol.XMLStream`
           is :meth:`~.protocol.XMLStream.abort`\ -ed if SM is enabled and
           :meth:`~.protocol.XMLStream.close`\ -ed if SM is not enabled.

           .. versionchanged:: 0.6

              The closing behaviour was added.

        .. signal:: on_stream_destroyed(reason)

           The stream has been stopped in a manner which means that all state must
           be discarded.

           :param reason: The exception which caused the stream to be destroyed.
           :type reason: :class:`Exception`

           When this signal is emitted, others have or will most likely see
           unavailable presence from the XMPP resource associated with the stream,
           and stanzas sent in the mean time are not guaranteed to be received.

           `reason` may be a :class:`DestructionRequested` instance to indicate
           that the destruction was requested by the user, in some way.

           There is no guarantee (it is not even likely) that it is possible to
           send stanzas over the stream at the time this signal is emitted.

           .. versionchanged:: 0.8

              The `reason` argument was added.

        .. signal:: on_stream_established()

           When a stream is newly established, this signal is fired. This happens
           whenever a non-SM stream is started and whenever a stream which
           previously had SM disabled is started with SM enabled.

        .. signal:: on_message_received(stanza)

            Emits when a :class:`aioxmpp.Message` stanza has been received.

            :param stanza: The received stanza.
            :type stanza: :class:`aioxmpp.Message`

            .. seealso::

                :class:`aioxmpp.dispatcher.SimpleMessageDispatcher`
                    for a service which allows to register callbacks for messages
                    based on the sender and type of the message.

            .. versionadded:: 0.9

        .. signal:: on_presence_received(stanza)

            Emits when a :class:`aioxmpp.Presence` stanza has been received.

            :param stanza: The received stanza.
            :type stanza: :class:`aioxmpp.Presence`

            .. seealso::

                :class:`aioxmpp.dispatcher.SimplePresenceDispatcher`
                    for a service which allows to register callbacks for presences
                    based on the sender and type of the message.

            .. versionadded:: 0.9

        """

        _ALLOW_ENUM_COERCION = True

        on_failure = callbacks.Signal()
        on_stream_destroyed = callbacks.Signal()
        on_stream_established = callbacks.Signal()

        on_message_received = callbacks.Signal()
        on_presence_received = callbacks.Signal()

        def __init__(self,
                     local_jid=None,
                     *,
                     loop=None,
                     base_logger=logging.getLogger("aioxmpp")):
            super().__init__()
            self._loop = loop or asyncio.get_event_loop()
            self._logger = base_logger.getChild("StanzaStream")
            self._task = None

            self._xmlstream = None
            self._soft_timeout = timedelta(minutes=1)
            self._round_trip_time = timedelta(minutes=1)

            self._xxx_message_dispatcher = None
            self._xxx_presence_dispatcher = None

            self._local_jid = local_jid

            self._active_queue = custom_queue.AsyncDeque(loop=self._loop)
            self._incoming_queue = custom_queue.AsyncDeque(loop=self._loop)

            self._iq_response_map = callbacks.TagDispatcher()
            self._iq_request_map = {}

            # list of running IQ request coroutines: used to cancel them when the
            # stream is destroyed
            self._iq_request_tasks = []

            self._xmlstream_exception = None

            self._established = False
            self._closed = False

            self._sm_enabled = False

            self._broker_lock = asyncio.Lock(loop=loop)

            self.app_inbound_presence_filter = AppFilter()
            self.service_inbound_presence_filter = callbacks.Filter()

            self.app_inbound_message_filter = AppFilter()
            self.service_inbound_message_filter = callbacks.Filter()

            self.app_outbound_presence_filter = AppFilter()
            self.service_outbound_presence_filter = callbacks.Filter()

            self.app_outbound_message_filter = AppFilter()
            self.service_outbound_message_filter = callbacks.Filter()

        @property
        def local_jid(self):
            """
            The `local_jid` argument to the constructor.

            .. warning::

               Changing this arbitrarily while the stream is running may have
               unintended side effects.

            """
            return self._local_jid

        @local_jid.setter
        def local_jid(self, value):
            self._local_jid = value

        @property
        def round_trip_time(self):
            """
            The maximum expected round-trip time as :class:`datetime.timedelta`.

            This is used to configure the maximum time between asking the server to
            send something and receiving something from the server in stream
            aliveness checks.

            This does **not** affect IQ requests or other stanzas.

            If set to :data:`None`, no application-level timeouts are used at all.
            This is not recommended since TCP timeouts are generally not sufficient
            for interactive applications.
            """
            return self._round_trip_time

        @round_trip_time.setter
        def round_trip_time(self, value):
            self._round_trip_time = value
            self._update_xmlstream_limits()

        @property
        def soft_timeout(self):
            """
            Soft timeout after which the server will be asked to send something
            if nothing has been received.

            If set to :data:`None`, no application-level timeouts are used at all.
            This is not recommended since TCP timeouts are generally not sufficient
            for interactive applications.
            """
            return self._soft_timeout

        @soft_timeout.setter
        def soft_timeout(self, value):
            self._soft_timeout = value
            self._update_xmlstream_limits()

        def _coerce_enum(self, value, enum_class):
            if not isinstance(value, enum_class):
                if self._ALLOW_ENUM_COERCION:
                    warnings.warn(
                        "passing a non-enum value as type_ is deprecated and will "
                        "be invalid as of aioxmpp 1.0",
                        DeprecationWarning,
                        stacklevel=3)
                    return enum_class(value)
                else:
                    raise TypeError("type_ must be {}, got {!r}".format(
                        enum_class.__name__,
                        value
                    ))
            return value

        def _done_handler(self, task):
            """
            Called when the main task (:meth:`_run`, :attr:`_task`) returns.
            """
            try:
                task.result()
            except asyncio.CancelledError:
                # normal termination
                pass
            except Exception as err:
                try:
                    if self._sm_enabled:
                        self._xmlstream.abort()
                    else:
                        self._xmlstream.close()
                except Exception:
                    pass
                self.on_failure(err)
                self._logger.exception("broker task failed")

        def _xmlstream_failed(self, exc):
            self._xmlstream_exception = exc
            self.stop()

        def _destroy_stream_state(self, exc):
            """
            Destroy all state which does not make sense to keep after a disconnect
            (without stream management).
            """
            self._logger.debug("destroying stream state (exc=%r)", exc)
            self._iq_response_map.close_all(exc)
            for task in self._iq_request_tasks:
                # we don’t need to remove, that’s handled by their
                # add_done_callback
                task.cancel()
            while not self._active_queue.empty():
                token = self._active_queue.get_nowait()
                token._set_state(StanzaState.DISCONNECTED)

            if self._established:
                self.on_stream_destroyed(exc)
                self._established = False

        def _iq_request_coro_done(self, request, task):
            """
            Called when an IQ request handler coroutine returns. `request` holds
            the IQ request which triggered the excecution of the coroutine and
            `task` is the :class:`asyncio.Task` which tracks the running coroutine.

            Compose a response and send that response.
            """
            self._iq_request_tasks.remove(task)
            try:
                payload = task.result()
            except errors.XMPPError as err:
                response = request.make_reply(type_=structs.IQType.ERROR)
                response.error = stanza.Error.from_exception(err)
            except Exception:
                response = request.make_reply(type_=structs.IQType.ERROR)
                response.error = stanza.Error(
                    condition=errors.ErrorCondition.UNDEFINED_CONDITION,
                    type_=structs.ErrorType.CANCEL,
                )
                self._logger.exception("IQ request coroutine failed")
            else:
                response = request.make_reply(type_=structs.IQType.RESULT)
                response.payload = payload
            self._enqueue(response)

        def _process_incoming_iq(self, stanza_obj):
            """
            Process an incoming IQ stanza `stanza_obj`. Calls the response handler,
            spawns a request handler coroutine or drops the stanza while logging a
            warning if no handler can be found.
            """
            self._logger.debug("incoming iq: %r", stanza_obj)
            if stanza_obj.type_.is_response:
                # iq response
                self._logger.debug("iq is response")
                keys = [(stanza_obj.from_, stanza_obj.id_)]
                if self._local_jid is not None:
                    # needed for some servers
                    if keys[0][0] == self._local_jid:
                        keys.append((None, keys[0][1]))
                    elif keys[0][0] is None:
                        keys.append((self._local_jid, keys[0][1]))
                for key in keys:
                    try:
                        self._iq_response_map.unicast(key, stanza_obj)
                        self._logger.debug("iq response delivered to key %r", key)
                        break
                    except KeyError:
                        pass
                else:
                    self._logger.warning(
                        "unexpected IQ response: from=%r, id=%r",
                        *key)
            else:
                # iq request
                self._logger.debug("iq is request")
                key = (stanza_obj.type_, type(stanza_obj.payload))
                try:
                    coro = self._iq_request_map[key]
                except KeyError:
                    self._logger.warning(
                        "unhandleable IQ request: from=%r, type_=%r, payload=%r",
                        stanza_obj.from_,
                        stanza_obj.type_,
                        stanza_obj.payload
                    )
                    response = stanza_obj.make_reply(type_=structs.IQType.ERROR)
                    response.error = stanza.Error(
                        condition=errors.ErrorCondition.SERVICE_UNAVAILABLE,
                    )
                    self._enqueue(response)
                    return

                try:
                    awaitable = coro(stanza_obj)
                except Exception as exc:
                    awaitable = asyncio.Future()
                    awaitable.set_exception(exc)

                task = asyncio.ensure_future(awaitable)
                task.add_done_callback(
                    functools.partial(
                        self._iq_request_coro_done,
                        stanza_obj))
                self._iq_request_tasks.append(task)
                self._logger.debug("started task to handle request: %r", task)

        def _process_incoming_message(self, stanza_obj):
            """
            Process an incoming message stanza `stanza_obj`.
            """
            self._logger.debug("incoming message: %r", stanza_obj)

            stanza_obj = self.service_inbound_message_filter.filter(stanza_obj)
            if stanza_obj is None:
                self._logger.debug("incoming message dropped by service "
                                   "filter chain")
                return

            stanza_obj = self.app_inbound_message_filter.filter(stanza_obj)
            if stanza_obj is None:
                self._logger.debug("incoming message dropped by application "
                                   "filter chain")
                return

            self.on_message_received(stanza_obj)

        def _process_incoming_presence(self, stanza_obj):
            """
            Process an incoming presence stanza `stanza_obj`.
            """
            self._logger.debug("incoming presence: %r", stanza_obj)

            stanza_obj = self.service_inbound_presence_filter.filter(stanza_obj)
            if stanza_obj is None:
                self._logger.debug("incoming presence dropped by service filter"
                                   " chain")
                return

            stanza_obj = self.app_inbound_presence_filter.filter(stanza_obj)
            if stanza_obj is None:
                self._logger.debug("incoming presence dropped by application "
                                   "filter chain")
                return

            self.on_presence_received(stanza_obj)

        def _process_incoming_erroneous_stanza(self, stanza_obj, exc):
            self._logger.debug(
                "erroneous stanza received (may be incomplete): %r",
                stanza_obj
            )

            try:
                type_ = stanza_obj.type_
            except AttributeError:
                # ugh, type is broken
                # exit early
                self._logger.debug(
                    "stanza has broken type, cannot properly handle"
                )
                return

            if type_.is_response:
                try:
                    from_ = stanza_obj.from_
                    id_ = stanza_obj.id_
                except AttributeError:
                    pass
                else:
                    if isinstance(stanza_obj, stanza.IQ):
                        self._logger.debug(
                            "erroneous stanza can be forwarded to handlers as "
                            "error"
                        )

                        key = (from_, id_)
                        try:
                            self._iq_response_map.unicast_error(
                                key,
                                errors.ErroneousStanza(stanza_obj)
                            )
                        except KeyError:
                            pass
            elif isinstance(exc, stanza.UnknownIQPayload):
                reply = stanza_obj.make_error(error=stanza.Error(
                    condition=errors.ErrorCondition.SERVICE_UNAVAILABLE
                ))
                self._enqueue(reply)
            elif isinstance(exc, stanza.PayloadParsingError):
                reply = stanza_obj.make_error(error=stanza.Error(
                    condition=errors.ErrorCondition.BAD_REQUEST
                ))
                self._enqueue(reply)

        def _process_incoming(self, xmlstream, queue_entry):
            """
            Dispatch to the different methods responsible for the different stanza
            types or handle a non-stanza stream-level element from `stanza_obj`,
            which has arrived over the given `xmlstream`.
            """

            stanza_obj, exc = queue_entry

            # first, handle SM stream objects
            if isinstance(stanza_obj, nonza.SMAcknowledgement):
                self._logger.debug("received SM ack: %r", stanza_obj)
                if not self._sm_enabled:
                    self._logger.warning("received SM ack, but SM not enabled")
                    return
                self.sm_ack(stanza_obj.counter)
                return
            elif isinstance(stanza_obj, nonza.SMRequest):
                self._logger.debug("received SM request: %r", stanza_obj)
                if not self._sm_enabled:
                    self._logger.warning("received SM request, but SM not enabled")
                    return
                response = nonza.SMAcknowledgement()
                response.counter = self._sm_inbound_ctr
                self._logger.debug("sending SM ack: %r", response)
                xmlstream.send_xso(response)
                return

            # raise if it is not a stanza
            if not isinstance(stanza_obj, stanza.StanzaBase):
                raise RuntimeError(
                    "unexpected stanza class: {}".format(stanza_obj))

            # now handle stanzas, these always increment the SM counter
            if self._sm_enabled:
                self._sm_inbound_ctr += 1
                self._sm_inbound_ctr &= 0xffffffff

            # check if the stanza has errors
            if exc is not None:
                self._process_incoming_erroneous_stanza(stanza_obj, exc)
                return

            if isinstance(stanza_obj, stanza.IQ):
                self._process_incoming_iq(stanza_obj)
            elif isinstance(stanza_obj, stanza.Message):
                self._process_incoming_message(stanza_obj)
            elif isinstance(stanza_obj, stanza.Presence):
                self._process_incoming_presence(stanza_obj)

        def flush_incoming(self):
            """
            Flush all incoming queues to the respective processing methods. The
            handlers are called as usual, thus it may require at least one
            iteration through the asyncio event loop before effects can be seen.

            The incoming queues are empty after a call to this method.

            It is legal (but pretty useless) to call this method while the stream
            is :attr:`running`.
            """
            while True:
                try:
                    stanza_obj = self._incoming_queue.get_nowait()
                except asyncio.QueueEmpty:
                    break
                self._process_incoming(None, stanza_obj)

        def _send_stanza(self, xmlstream, token):
            """
            Send a stanza token `token` over the given `xmlstream`.

            Only sends if the `token` has not been aborted (see
            :meth:`StanzaToken.abort`). Sends the state of the token acoording to
            :attr:`sm_enabled`.
            """
            if token.state == StanzaState.ABORTED:
                return

            stanza_obj = token.stanza

            if isinstance(stanza_obj, stanza.Presence):
                stanza_obj = self.app_outbound_presence_filter.filter(
                    stanza_obj
                )
                if stanza_obj is not None:
                    stanza_obj = self.service_outbound_presence_filter.filter(
                        stanza_obj
                    )
            elif isinstance(stanza_obj, stanza.Message):
                stanza_obj = self.app_outbound_message_filter.filter(
                    stanza_obj
                )
                if stanza_obj is not None:
                    stanza_obj = self.service_outbound_message_filter.filter(
                        stanza_obj
                    )

            if stanza_obj is None:
                token._set_state(StanzaState.DROPPED)
                self._logger.debug("outgoing stanza %r dropped by filter chain",
                                   token.stanza)
                return

            self._logger.debug("forwarding stanza to xmlstream: %r",
                               stanza_obj)

            try:
                xmlstream.send_xso(stanza_obj)
            except Exception as exc:
                self._logger.warning("failed to send stanza", exc_info=True)
                token._set_state(StanzaState.FAILED, exc)
                return

            if self._sm_enabled:
                token._set_state(StanzaState.SENT)
                self._sm_unacked_list.append(token)
            else:
                token._set_state(StanzaState.SENT_WITHOUT_SM)

        def _process_outgoing(self, xmlstream, token):
            """
            Process the current outgoing stanza `token` and also any other outgoing
            stanza which is currently in the active queue. After all stanzas have
            been processed, use :meth:`_send_ping` to allow an opportunistic ping
            to be sent.
            """

            self._send_stanza(xmlstream, token)
            # try to send a bulk
            while True:
                try:
                    token = self._active_queue.get_nowait()
                except asyncio.QueueEmpty:
                    break
                self._send_stanza(xmlstream, token)

            if self._sm_enabled:
                self._logger.debug("sending SM req")
                xmlstream.send_xso(nonza.SMRequest())

        def register_iq_response_callback(self, from_, id_, cb):
            """
            Register a callback function `cb` to be called when a IQ stanza with
            type ``result`` or ``error`` is recieved from the
            :class:`~aioxmpp.JID` `from_` with the id `id_`.

            The callback is called at most once.

            .. note::

               In contrast to :meth:`register_iq_response_future`, errors which
               occur on a level below XMPP stanzas cannot be caught using a
               callback.

               If you need notification about other errors and still want to use
               callbacks, use of a future with
               :meth:`asyncio.Future.add_done_callback` is recommended.

            """

            self._iq_response_map.add_listener(
                (from_, id_),
                callbacks.OneshotAsyncTagListener(cb, loop=self._loop)
            )
            self._logger.debug("iq response callback registered: from=%r, id=%r",
                               from_, id_)

        def register_iq_response_future(self, from_, id_, fut):
            """
            Register a future `fut` for an IQ stanza with type ``result`` or
            ``error`` from the :class:`~aioxmpp.JID` `from_` with the id
            `id_`.

            If the type of the IQ stanza is ``result``, the stanza is set as result
            to the future. If the type of the IQ stanza is ``error``, the stanzas
            error field is converted to an exception and set as the exception of
            the future.

            The future might also receive different exceptions:

            * :class:`.errors.ErroneousStanza`, if the response stanza received
              could not be parsed.

              Note that this exception is not emitted if the ``from`` address of
              the stanza is unset, because the code cannot determine whether a
              sender deliberately used an erroneous address to make parsing fail
              or no sender address was used. In the former case, an attacker could
              use that to inject a stanza which would be taken as a stanza from the
              peer server. Thus, the future will never be fulfilled in these
              cases.

              Also note that this exception does not derive from
              :class:`.errors.XMPPError`, as it cannot provide the same
              attributes. Instead, it dervies from :class:`.errors.StanzaError`,
              from which :class:`.errors.XMPPError` also derives; to catch all
              possible stanza errors, catching :class:`.errors.StanzaError` is
              sufficient and future-proof.

            * :class:`ConnectionError` if the stream is :meth:`stop`\ -ped (only if
              SM is not enabled) or :meth:`close`\ -ed.

            * Any :class:`Exception` which may be raised from
              :meth:`~.protocol.XMLStream.send_xso`, which are generally also
              :class:`ConnectionError` or at least :class:`OSError` subclasses.

            """

            self._iq_response_map.add_listener(
                (from_, id_),
                StanzaErrorAwareListener(
                    callbacks.FutureListener(fut)
                )
            )
            self._logger.debug("iq response future registered: from=%r, id=%r",
                               from_, id_)

        def unregister_iq_response(self, from_, id_):
            """
            Unregister a registered callback or future for the IQ response
            identified by `from_` and `id_`. See
            :meth:`register_iq_response_future` or
            :meth:`register_iq_response_callback` for details on the arguments
            meanings and how to register futures and callbacks respectively.

            .. note::

               Futures will automatically be unregistered when they are cancelled.

            """
            self._iq_response_map.remove_listener((from_, id_))
            self._logger.debug("iq response unregistered: from=%r, id=%r",
                               from_, id_)

        def register_iq_request_coro(self, type_, payload_cls, coro):
            """
            Alias of :meth:`register_iq_request_handler`.

            .. deprecated:: 0.10

                This alias will be removed in version 1.0.
            """
            warnings.warn(
                "register_iq_request_coro is a deprecated alias to "
                "register_iq_request_handler and will be removed in aioxmpp 1.0",
                DeprecationWarning,
                stacklevel=2)
            return self.register_iq_request_handler(type_, payload_cls, coro)

        def register_iq_request_handler(self, type_, payload_cls, cb):
            """
            Register a coroutine function or a function returning an awaitable to
            run when an IQ request is received.

            :param type_: IQ type to react to (must be a request type).
            :type type_: :class:`~aioxmpp.IQType`
            :param payload_cls: Payload class to react to (subclass of
                :class:`~xso.XSO`)
            :type payload_cls: :class:`~.XMLStreamClass`
            :param cb: Function or coroutine function to invoke
            :raises ValueError: if there is already a coroutine registered for this
                                target
            :raises ValueError: if `type_` is not a request IQ type
            :raises ValueError: if `type_` is not a valid
                                :class:`~.IQType` (and cannot be cast to a
                                :class:`~.IQType`)

            The callback `cb` will be called whenever an IQ stanza with the given
            `type_` and payload being an instance of the `payload_cls` is received.

            The callback must either be a coroutine function or otherwise return an
            awaitable. The awaitable must evaluate to a valid value for the
            :attr:`.IQ.payload` attribute. That value will be set as the payload
            attribute value of an IQ response (with type :attr:`~.IQType.RESULT`)
            which is generated and sent by the stream.

            If the awaitable or the function raises an exception, it will be
            converted to a :class:`~.stanza.Error` object. That error object is
            then used as payload for an IQ response (with type
            :attr:`~.IQType.ERROR`) which is generated and sent by the stream.

            If the exception is a subclass of :class:`aioxmpp.errors.XMPPError`, it
            is converted to an :class:`~.stanza.Error` instance directly.
            Otherwise, it is wrapped in a :class:`aioxmpp.XMPPCancelError`
            with ``undefined-condition``.

            For this to work, `payload_cls` *must* be registered using
            :meth:`~.IQ.as_payload_class`. Otherwise, the payload will
            not be recognised by the stream parser and the IQ is automatically
            responded to with a ``feature-not-implemented`` error.

            .. warning::

                When using a coroutine function for `cb`, there is no guarantee
                that concurrent IQ handlers and other coroutines will execute in
                any defined order. This implies that the strong ordering guarantees
                normally provided by XMPP XML Streams are lost when using coroutine
                functions for `cb`. For this reason, the use of non-coroutine
                functions is allowed.

            .. note::

                Using a non-coroutine function for `cb` will generally lead to
                less readable code. For the sake of readability, it is recommended
                prefer coroutine functions.

            .. versionchanged:: 0.10

                Accepts an awaitable as last argument in addition to coroutine
                functions.

                Renamed from :meth:`register_iq_request_coro`.

            .. versionadded:: 0.6

               If the stream is :meth:`stop`\ -ped (only if SM is not enabled) or
               :meth:`close`\ ed, running IQ response coroutines are
               :meth:`asyncio.Task.cancel`\ -led.

               To protect against that, fork from your coroutine using
               :func:`asyncio.ensure_future`.

            .. versionchanged:: 0.7

               The `type_` argument is now supposed to be a :class:`~.IQType`
               member.

            .. deprecated:: 0.7

               Passing a :class:`str` as `type_` argument is deprecated and will
               raise a :class:`TypeError` as of the 1.0 release. See the Changelog
               for :ref:`api-changelog-0.7` for further details on how to upgrade
               your code efficiently.
            """
            type_ = self._coerce_enum(type_, structs.IQType)
            if not type_.is_request:
                raise ValueError(
                    "{!r} is not a request IQType".format(type_)
                )

            key = type_, payload_cls

            if key in self._iq_request_map:
                raise ValueError("only one listener is allowed per tag")

            self._iq_request_map[key] = cb
            self._logger.debug(
                "iq request coroutine registered: type=%r, payload=%r",
                type_, payload_cls)

        def unregister_iq_request_coro(self, type_, payload_cls):
            warnings.warn(
                "unregister_iq_request_coro is a deprecated alias to "
                "unregister_iq_request_handler and will be removed in aioxmpp 1.0",
                DeprecationWarning,
                stacklevel=2,
            )
            return self.unregister_iq_request_handler(type_, payload_cls)

        def unregister_iq_request_handler(self, type_, payload_cls):
            """
            Unregister a coroutine previously registered with
            :meth:`register_iq_request_handler`.

            :param type_: IQ type to react to (must be a request type).
            :type type_: :class:`~structs.IQType`
            :param payload_cls: Payload class to react to (subclass of
                :class:`~xso.XSO`)
            :type payload_cls: :class:`~.XMLStreamClass`
            :raises KeyError: if no coroutine has been registered for the given
                              ``(type_, payload_cls)`` pair
            :raises ValueError: if `type_` is not a valid
                                :class:`~.IQType` (and cannot be cast to a
                                :class:`~.IQType`)

            The match is solely made using the `type_` and `payload_cls` arguments,
            which have the same meaning as in :meth:`register_iq_request_coro`.

            .. versionchanged:: 0.10

                Renamed from :meth:`unregister_iq_request_coro`.

            .. versionchanged:: 0.7

               The `type_` argument is now supposed to be a :class:`~.IQType`
               member.

            .. deprecated:: 0.7

               Passing a :class:`str` as `type_` argument is deprecated and will
               raise a :class:`TypeError` as of the 1.0 release. See the Changelog
               for :ref:`api-changelog-0.7` for further details on how to upgrade
               your code efficiently.
            """
            type_ = self._coerce_enum(type_, structs.IQType)
            del self._iq_request_map[type_, payload_cls]
            self._logger.debug(
                "iq request coroutine unregistered: type=%r, payload=%r",
                type_, payload_cls)

        def register_message_callback(self, type_, from_, cb):
            """
            Register a callback to be called when a message is received.

            :param type_: Message type to listen for, or :data:`None` for a
                          wildcard match.
            :type type_: :class:`~.MessageType` or :data:`None`
            :param from_: Sender JID to listen for, or :data:`None` for a wildcard
                          match.
            :type from_: :class:`~aioxmpp.JID` or :data:`None`
            :param cb: Callback function to call
            :raises ValueError: if another function is already registered for the
                                same ``(type_, from_)`` pair.
            :raises ValueError: if `type_` is not a valid
                                :class:`~.MessageType` (and cannot be cast
                                to a :class:`~.MessageType`)

            `cb` will be called whenever a message stanza matching the `type_` and
            `from_` is received, according to the wildcarding rules below. More
            specific callbacks win over less specific callbacks, and the match on
            the `from_` address takes precedence over the match on the `type_`.

            See :meth:`.SimpleStanzaDispatcher.register_callback` for the exact
            wildcarding rules.

            .. versionchanged:: 0.7

               The `type_` argument is now supposed to be a
               :class:`~.MessageType` member.

            .. deprecated:: 0.7

               Passing a :class:`str` as `type_` argument is deprecated and will
               raise a :class:`TypeError` as of the 1.0 release. See the Changelog
               for :ref:`api-changelog-0.7` for further details on how to upgrade
               your code efficiently.

            .. deprecated:: 0.9

               This method has been deprecated in favour of and is now implemented
               in terms of the :class:`aioxmpp.dispatcher.SimpleMessageDispatcher`
               service.

               It is equivalent to call
               :meth:`~.SimpleStanzaDispatcher.register_callback`, except that the
               latter is not deprecated.
            """
            if type_ is not None:
                type_ = self._coerce_enum(type_, structs.MessageType)
            warnings.warn(
                "register_message_callback is deprecated; use "
                "aioxmpp.dispatcher.SimpleMessageDispatcher instead",
                DeprecationWarning,
                stacklevel=2
            )
            self._xxx_message_dispatcher.register_callback(
                type_,
                from_,
                cb,
            )

        def unregister_message_callback(self, type_, from_):
            """
            Unregister a callback previously registered with
            :meth:`register_message_callback`.

            :param type_: Message type to listen for.
            :type type_: :class:`~.MessageType` or :data:`None`
            :param from_: Sender JID to listen for.
            :type from_: :class:`~aioxmpp.JID` or :data:`None`
            :raises KeyError: if no function is currently registered for the given
                              ``(type_, from_)`` pair.
            :raises ValueError: if `type_` is not a valid
                                :class:`~.MessageType` (and cannot be cast
                                to a :class:`~.MessageType`)

            The match is made on the exact pair; it is not possible to unregister
            arbitrary listeners by passing :data:`None` to both arguments (i.e. the
            wildcarding only applies for receiving stanzas, not for unregistering
            callbacks; unregistering the super-wildcard with both arguments set to
            :data:`None` is of course possible).

            .. versionchanged:: 0.7

               The `type_` argument is now supposed to be a
               :class:`~.MessageType` member.

            .. deprecated:: 0.7

               Passing a :class:`str` as `type_` argument is deprecated and will
               raise a :class:`TypeError` as of the 1.0 release. See the Changelog
               for :ref:`api-changelog-0.7` for further details on how to upgrade
               your code efficiently.

            .. deprecated:: 0.9

               This method has been deprecated in favour of and is now implemented
               in terms of the :class:`aioxmpp.dispatcher.SimpleMessageDispatcher`
               service.

               It is equivalent to call
               :meth:`~.SimpleStanzaDispatcher.unregister_callback`, except that
               the latter is not deprecated.
            """
            if type_ is not None:
                type_ = self._coerce_enum(type_, structs.MessageType)
            warnings.warn(
                "unregister_message_callback is deprecated; use "
                "aioxmpp.dispatcher.SimpleMessageDispatcher instead",
                DeprecationWarning,
                stacklevel=2
            )
            self._xxx_message_dispatcher.unregister_callback(
                type_,
                from_,
            )

        def register_presence_callback(self, type_, from_, cb):
            """
            Register a callback to be called when a presence stanza is received.

            :param type_: Presence type to listen for.
            :type type_: :class:`~.PresenceType`
            :param from_: Sender JID to listen for, or :data:`None` for a wildcard
                          match.
            :type from_: :class:`~aioxmpp.JID` or :data:`None`.
            :param cb: Callback function
            :raises ValueError: if another listener with the same ``(type_,
                                from_)`` pair is already registered
            :raises ValueError: if `type_` is not a valid
                                :class:`~.PresenceType` (and cannot be cast
                                to a :class:`~.PresenceType`)

            `cb` will be called whenever a presence stanza matching the `type_` is
            received from the specified sender. `from_` may be :data:`None` to
            indicate a wildcard. Like with :meth:`register_message_callback`, more
            specific callbacks win over less specific callbacks. The fallback order
            is identical, except that the ``type_=None`` entries described there do
            not apply for presence stanzas and are thus omitted.

            See :meth:`.SimpleStanzaDispatcher.register_callback` for the exact
            wildcarding rules.

            .. versionchanged:: 0.7

               The `type_` argument is now supposed to be a
               :class:`~.PresenceType` member.

            .. deprecated:: 0.7

               Passing a :class:`str` as `type_` argument is deprecated and will
               raise a :class:`TypeError` as of the 1.0 release. See the Changelog
               for :ref:`api-changelog-0.7` for further details on how to upgrade
               your code efficiently.

            .. deprecated:: 0.9

               This method has been deprecated. It is recommended to use
               :class:`aioxmpp.PresenceClient` instead.

            """
            type_ = self._coerce_enum(type_, structs.PresenceType)
            warnings.warn(
                "register_presence_callback is deprecated; use "
                "aioxmpp.dispatcher.SimplePresenceDispatcher or "
                "aioxmpp.PresenceClient instead",
                DeprecationWarning,
                stacklevel=2
            )
            self._xxx_presence_dispatcher.register_callback(
                type_,
                from_,
                cb,
            )

        def unregister_presence_callback(self, type_, from_):
            """
            Unregister a callback previously registered with
            :meth:`register_presence_callback`.

            :param type_: Presence type to listen for.
            :type type_: :class:`~.PresenceType`
            :param from_: Sender JID to listen for, or :data:`None` for a wildcard
                          match.
            :type from_: :class:`~aioxmpp.JID` or :data:`None`.
            :raises KeyError: if no callback is currently registered for the given
                              ``(type_, from_)`` pair
            :raises ValueError: if `type_` is not a valid
                                :class:`~.PresenceType` (and cannot be cast
                                to a :class:`~.PresenceType`)

            The match is made on the exact pair; it is not possible to unregister
            arbitrary listeners by passing :data:`None` to the `from_` arguments
            (i.e. the wildcarding only applies for receiving stanzas, not for
            unregistering callbacks; unregistering a wildcard match with `from_`
            set to :data:`None` is of course possible).

            .. versionchanged:: 0.7

               The `type_` argument is now supposed to be a
               :class:`~.PresenceType` member.

            .. deprecated:: 0.7

               Passing a :class:`str` as `type_` argument is deprecated and will
               raise a :class:`TypeError` as of the 1.0 release. See the Changelog
               for :ref:`api-changelog-0.7` for further details on how to upgrade
               your code efficiently.

            .. deprecated:: 0.9

               This method has been deprecated. It is recommended to use
               :class:`aioxmpp.PresenceClient` instead.

            """
            type_ = self._coerce_enum(type_, structs.PresenceType)
            warnings.warn(
                "unregister_presence_callback is deprecated; use "
                "aioxmpp.dispatcher.SimplePresenceDispatcher or "
                "aioxmpp.PresenceClient instead",
                DeprecationWarning,
                stacklevel=2
            )
            self._xxx_presence_dispatcher.unregister_callback(
                type_,
                from_,
            )

        def _xmlstream_soft_limit_tripped(self, xmlstream):
            self._logger.debug(
                "XMLStream has reached dead-time soft limit, sending ping"
            )

            if self._sm_enabled:
                req = nonza.SMRequest()
                xmlstream.send_xso(req)
            else:
                iq = stanza.IQ(
                    type_=structs.IQType.GET,
                    payload=ping.Ping()
                )
                iq.autoset_id()
                self.register_iq_response_callback(
                    None,
                    iq.id_,
                    # we don’t care, just wanna make sure that this doesn’t fail
                    lambda stanza: None,
                )
                self._enqueue(iq)

        def _start_prepare(self, xmlstream, receiver):
            self._xmlstream_failure_token = xmlstream.on_closing.connect(
                self._xmlstream_failed
            )

            self._xmlstream_soft_limit_token = \
                xmlstream.on_deadtime_soft_limit_tripped.connect(
                    functools.partial(self._xmlstream_soft_limit_tripped,
                                      xmlstream)
                )

            xmlstream.stanza_parser.add_class(stanza.IQ, receiver)
            xmlstream.stanza_parser.add_class(stanza.Message, receiver)
            xmlstream.stanza_parser.add_class(stanza.Presence, receiver)
            xmlstream.error_handler = self.recv_erroneous_stanza

            if self._sm_enabled:
                self._logger.debug("using SM")
                xmlstream.stanza_parser.add_class(nonza.SMAcknowledgement,
                                                  receiver)
                xmlstream.stanza_parser.add_class(nonza.SMRequest,
                                                  receiver)

            self._xmlstream_exception = None

        def _start_rollback(self, xmlstream):
            xmlstream.error_handler = None
            xmlstream.stanza_parser.remove_class(stanza.Presence)
            xmlstream.stanza_parser.remove_class(stanza.Message)
            xmlstream.stanza_parser.remove_class(stanza.IQ)
            if self._sm_enabled:
                xmlstream.stanza_parser.remove_class(
                    nonza.SMRequest)
                xmlstream.stanza_parser.remove_class(
                    nonza.SMAcknowledgement)

            xmlstream.on_closing.disconnect(
                self._xmlstream_failure_token
            )
            xmlstream.on_deadtime_soft_limit_tripped.disconnect(
                self._xmlstream_soft_limit_token
            )

        def _update_xmlstream_limits(self):
            if self._xmlstream is None:
                return

            self._xmlstream.deadtime_soft_limit = self._soft_timeout
            if (self._soft_timeout is not None and
                    self._round_trip_time is not None):
                self._xmlstream.deadtime_hard_limit = \
                    self._soft_timeout + self._round_trip_time
            else:
                self._xmlstream.deadtime_hard_limit = None

        def _start_commit(self, xmlstream):
            if not self._established:
                self.on_stream_established()
                self._established = True

            self._task = asyncio.ensure_future(self._run(xmlstream),
                                               loop=self._loop)
            self._task.add_done_callback(self._done_handler)
            self._logger.debug("broker task started as %r", self._task)

        def start(self, xmlstream):
            """
            Start or resume the stanza stream on the given
            :class:`aioxmpp.protocol.XMLStream` `xmlstream`.

            This starts the main broker task, registers stanza classes at the
            `xmlstream` .
            """

            if self.running:
                raise RuntimeError("already started")

            self._start_prepare(xmlstream, self.recv_stanza)
            self._closed = False
            self._start_commit(xmlstream)

        def stop(self):
            """
            Send a signal to the main broker task to terminate. You have to check
            :attr:`running` and possibly wait for it to become :data:`False` ---
            the task takes at least one loop through the event loop to terminate.

            It is guarenteed that the task will not attempt to send stanzas over
            the existing `xmlstream` after a call to :meth:`stop` has been made.

            It is legal to call :meth:`stop` even if the task is already
            stopped. It is a no-op in that case.
            """
            if not self.running:
                return
            self._logger.debug("sending stop signal to task")
            self._task.cancel()

        @asyncio.coroutine
        def wait_stop(self):
            """
            Stop the stream and wait for it to stop.

            See :meth:`stop` for the general stopping conditions. You can assume
            that :meth:`stop` is the first thing this coroutine calls.
            """
            if not self.running:
                return
            self.stop()
            try:
                yield from self._task
            except asyncio.CancelledError:
                pass

        @asyncio.coroutine
        def close(self):
            """
            Close the stream and the underlying XML stream (if any is connected).

            This is essentially a way of saying "I do not want to use this stream
            anymore" (until the next call to :meth:`start`). If the stream is
            currently running, the XML stream is closed gracefully (potentially
            sending an SM ack), the worker is stopped and any Stream Management
            state is cleaned up.

            If an error occurs while the stream stops, the error is ignored.

            After the call to :meth:`close` has started, :meth:`on_failure` will
            not be emitted, even if the XML stream fails before closure has
            completed.

            After a call to :meth:`close`, the stream is stopped, all SM state is
            discarded and calls to :meth:`enqueue_stanza` raise a
            :class:`DestructionRequested` ``"close() called"``. Such a
            :class:`StanzaStream` can be re-started by calling :meth:`start`.

            .. versionchanged:: 0.8

               Before 0.8, an error during a call to :meth:`close` would stop the
               stream from closing completely, and the exception was re-raised. If
               SM was enabled, the state would have been kept, allowing for
               resumption and ensuring that stanzas still enqueued or
               unacknowledged would get a chance to be sent.

               If you want to have guarantees that all stanzas sent up to a certain
               point are sent, you should be using :meth:`send_and_wait_for_sent`
               with stream management.
            """
            exc = DestructionRequested("close() called")

            if self.running:
                if self.sm_enabled:
                    self._xmlstream.send_xso(nonza.SMAcknowledgement(
                        counter=self._sm_inbound_ctr
                    ))

                yield from self._xmlstream.close_and_wait()  # does not raise
                yield from self.wait_stop()  # may raise

            self._closed = True
            self._xmlstream_exception = exc
            self._destroy_stream_state(self._xmlstream_exception)
            if self.sm_enabled:
                self.stop_sm()

        @asyncio.coroutine
        def _run(self, xmlstream):
            self._xmlstream = xmlstream
            self._update_xmlstream_limits()
            active_fut = asyncio.ensure_future(self._active_queue.get(),
                                               loop=self._loop)
            incoming_fut = asyncio.ensure_future(self._incoming_queue.get(),
                                                 loop=self._loop)

            try:
                while True:
                    timeout = None
                    done, pending = yield from asyncio.wait(
                        [
                            active_fut,
                            incoming_fut,
                        ],
                        return_when=asyncio.FIRST_COMPLETED,
                        timeout=timeout)

                    with (yield from self._broker_lock):
                        if active_fut in done:
                            self._process_outgoing(xmlstream, active_fut.result())
                            active_fut = asyncio.ensure_future(
                                self._active_queue.get(),
                                loop=self._loop)

                        if incoming_fut in done:
                            self._process_incoming(xmlstream,
                                                   incoming_fut.result())
                            incoming_fut = asyncio.ensure_future(
                                self._incoming_queue.get(),
                                loop=self._loop)

            finally:
                # make sure we rescue any stanzas which possibly have already been
                # caught by the calls to get()
                self._logger.debug("task terminating, rescuing stanzas and "
                                   "clearing handlers")
                if incoming_fut.done() and not incoming_fut.exception():
                    self._incoming_queue.putleft_nowait(incoming_fut.result())
                else:
                    incoming_fut.cancel()

                if active_fut.done() and not active_fut.exception():
                    self._active_queue.putleft_nowait(active_fut.result())
                else:
                    active_fut.cancel()

                # we also lock shutdown, because the main race is among the SM
                # variables
                with (yield from self._broker_lock):
                    if not self.sm_enabled or not self.sm_resumable:
                        self._destroy_stream_state(
                            self._xmlstream_exception or
                            DestructionRequested(
                                "close() or stop() called and stream is not "
                                "resumable"
                            )
                        )
                        if self.sm_enabled:
                            self._stop_sm()

                    self._start_rollback(xmlstream)

                if self._xmlstream_exception:
                    raise self._xmlstream_exception

        def recv_stanza(self, stanza):
            """
            Inject a `stanza` into the incoming queue.
            """
            self._incoming_queue.put_nowait((stanza, None))

        def recv_erroneous_stanza(self, partial_obj, exc):
            self._incoming_queue.put_nowait((partial_obj, exc))

        def _enqueue(self, stanza, **kwargs):
            if self._closed:
                raise self._xmlstream_exception

            stanza.validate()
            token = StanzaToken(stanza, **kwargs)
            self._active_queue.put_nowait(token)
            stanza.autoset_id()
            self._logger.debug("enqueued stanza %r with token %r",
                               stanza, token)
            return token

        enqueue_stanza = _enqueue

        def enqueue(self, stanza, **kwargs):
            """
            Deprecated alias of :meth:`aioxmpp.Client.enqueue`.

            This is only available on streams owned by a :class:`aioxmpp.Client`.

            .. deprecated:: 0.10
            """
            raise NotImplementedError(
                "only available on streams owned by a Client"
            )

        @property
        def running(self):
            """
            :data:`True` if the broker task is currently running, and :data:`False`
            otherwise.
            """
            return self._task is not None and not self._task.done()

        @asyncio.coroutine
        def start_sm(self, request_resumption=True, resumption_timeout=None):
            """
            Start stream management (version 3).

            :param request_resumption: Request that the stream shall be resumable.
            :type request_resumption: :class:`bool`
            :param resumption_timeout: Maximum time in seconds for a stream to be
                resumable.
            :type resumption_timeout: :class:`int`
            :raises aioxmpp.errors.StreamNegotiationFailure: if the server rejects
                the attempt to enable stream management.

            This method attempts to starts stream management on the stream.

            `resumption_timeout` is the ``max`` attribute on
            :class:`.nonza.SMEnabled`; it can be used to set a maximum time for
            which the server shall consider the stream to still be alive after the
            underlying transport (TCP) has failed. The server may impose its own
            maximum or ignore the request, so there are no guarentees that the
            session will stay alive for at most or at least `resumption_timeout`
            seconds. Passing a `resumption_timeout` of 0 is equivalent to passing
            false to `request_resumption` and takes precedence over
            `request_resumption`.

            .. note::

                In addition to server implementation details, it is very well
                possible that the server does not even detect that the underlying
                transport has failed for quite some time for various reasons
                (including high TCP timeouts).

            If the server rejects the attempt to enable stream management, a
            :class:`.errors.StreamNegotiationFailure` is raised. The stream is
            still running in that case.

            .. warning::

               This method cannot and does not check whether the server advertised
               support for stream management. Attempting to negotiate stream
               management without server support might lead to termination of the
               stream.

            If an XML stream error occurs during the negotiation, the result
            depends on a few factors. In any case, the stream is not running
            afterwards. If the :class:`.nonza.SMEnabled` response was not received
            before the XML stream died, SM is also disabled and the exception which
            caused the stream to die is re-raised (this is due to the
            implementation of :func:`~.protocol.send_and_wait_for`). If the
            :class:`.nonza.SMEnabled` response was received and annonuced support
            for resumption, SM is enabled. Otherwise, it is disabled. No exception
            is raised if :class:`.nonza.SMEnabled` was received, as this method has
            no way to determine that the stream failed.

            If negotiation succeeds, this coroutine initializes a new stream
            management session. The stream management state attributes become
            available and :attr:`sm_enabled` becomes :data:`True`.
            """
            if not self.running:
                raise RuntimeError("cannot start Stream Management while"
                                   " StanzaStream is not running")
            if self.sm_enabled:
                raise RuntimeError("Stream Management already enabled")

            if resumption_timeout == 0:
                request_resumption = False
                resumption_timeout = None

            # sorry for the callback spaghetti code
            # we have to handle the response synchronously, so we have to use a
            # callback.
            # otherwise, it is possible that an SM related nonza (e.g. <r/>) is
            # received (and attempted to be deserialized) before the handlers are
            # registered
            # see tests/test_highlevel.py:TestProtocoltest_sm_bootstrap_race
            def handle_response(response):
                if isinstance(response, nonza.SMFailed):
                    # we handle the error down below
                    return

                self._sm_outbound_base = 0
                self._sm_inbound_ctr = 0
                self._sm_unacked_list = []
                self._sm_enabled = True
                self._sm_id = response.id_
                self._sm_resumable = response.resume
                self._sm_max = response.max_
                self._sm_location = response.location

                self._logger.info("SM started: resumable=%s, stream id=%r",
                                  self._sm_resumable,
                                  self._sm_id)

                # if not self._xmlstream:
                #     # stream died in the meantime...
                #     if self._xmlstream_exception:
                #         raise self._xmlstream_exception

                self._xmlstream.stanza_parser.add_class(
                    nonza.SMRequest,
                    self.recv_stanza)
                self._xmlstream.stanza_parser.add_class(
                    nonza.SMAcknowledgement,
                    self.recv_stanza)

            with (yield from self._broker_lock):
                response = yield from protocol.send_and_wait_for(
                    self._xmlstream,
                    [
                        nonza.SMEnable(resume=bool(request_resumption),
                                       max_=resumption_timeout),
                    ],
                    [
                        nonza.SMEnabled,
                        nonza.SMFailed
                    ],
                    cb=handle_response,
                )

                if isinstance(response, nonza.SMFailed):
                    raise errors.StreamNegotiationFailure(
                        "Server rejected SM request")

        @property
        def sm_enabled(self):
            """
            :data:`True` if stream management is currently enabled on the stream,
            :data:`False` otherwise.
            """

            return self._sm_enabled

        @property
        def sm_outbound_base(self):
            """
            The last value of the remote stanza counter.

            .. note::

               Accessing this attribute when :attr:`sm_enabled` is :data:`False`
               raises :class:`RuntimeError`.

            """

            if not self.sm_enabled:
                raise RuntimeError("Stream Management not enabled")
            return self._sm_outbound_base

        @property
        def sm_inbound_ctr(self):
            """
            The current value of the inbound stanza counter.

            .. note::

               Accessing this attribute when :attr:`sm_enabled` is :data:`False`
               raises :class:`RuntimeError`.

            """

            if not self.sm_enabled:
                raise RuntimeError("Stream Management not enabled")
            return self._sm_inbound_ctr

        @property
        def sm_unacked_list(self):
            """
            A **copy** of the list of stanza tokens which have not yet been acked
            by the remote party.

            .. note::

               Accessing this attribute when :attr:`sm_enabled` is :data:`False`
               raises :class:`RuntimeError`.

               Accessing this attribute is expensive, as the list is copied. In
               general, access to this attribute should not be neccessary at all.

            """

            if not self.sm_enabled:
                raise RuntimeError("Stream Management not enabled")
            return self._sm_unacked_list[:]

        @property
        def sm_max(self):
            """
            The value of the ``max`` attribute of the
            :class:`~.nonza.SMEnabled` response from the server.

            .. note::

               Accessing this attribute when :attr:`sm_enabled` is :data:`False`
               raises :class:`RuntimeError`.

            """

            if not self.sm_enabled:
                raise RuntimeError("Stream Management not enabled")
            return self._sm_max

        @property
        def sm_location(self):
            """
            The value of the ``location`` attribute of the
            :class:`~.nonza.SMEnabled` response from the server.

            .. note::

               Accessing this attribute when :attr:`sm_enabled` is :data:`False`
               raises :class:`RuntimeError`.

            """

            if not self.sm_enabled:
                raise RuntimeError("Stream Management not enabled")
            return self._sm_location

        @property
        def sm_id(self):
            """
            The value of the ``id`` attribute of the
            :class:`~.nonza.SMEnabled` response from the server.

            .. note::

               Accessing this attribute when :attr:`sm_enabled` is :data:`False`
               raises :class:`RuntimeError`.

            """

            if not self.sm_enabled:
                raise RuntimeError("Stream Management not enabled")
            return self._sm_id

        @property
        def sm_resumable(self):
            """
            The value of the ``resume`` attribute of the
            :class:`~.nonza.SMEnabled` response from the server.

            .. note::

               Accessing this attribute when :attr:`sm_enabled` is :data:`False`
               raises :class:`RuntimeError`.

            """

            if not self.sm_enabled:
                raise RuntimeError("Stream Management not enabled")
            return self._sm_resumable

        def _resume_sm(self, remote_ctr):
            """
            Version of :meth:`resume_sm` which can be used during slow start.
            """
            self._logger.info("resuming SM stream with remote_ctr=%d", remote_ctr)
            # remove any acked stanzas
            self.sm_ack(remote_ctr)
            # reinsert the remaining stanzas
            for token in self._sm_unacked_list:
                self._active_queue.putleft_nowait(token)
            self._sm_unacked_list.clear()

        @asyncio.coroutine
        def resume_sm(self, xmlstream):
            """
            Resume an SM-enabled stream using the given `xmlstream`.

            If the server rejects the attempt to resume stream management, a
            :class:`.errors.StreamNegotiationFailure` is raised. The stream is then
            in stopped state and stream management has been stopped.

            .. warning::

               This method cannot and does not check whether the server advertised
               support for stream management. Attempting to negotiate stream
               management without server support might lead to termination of the
               stream.

            If the XML stream dies at any point during the negotiation, the SM
            state is left unchanged. If no response has been received yet, the
            exception which caused the stream to die is re-raised. The state of the
            stream depends on whether the main task already noticed the dead
            stream.

            If negotiation succeeds, this coroutine resumes the stream management
            session and initiates the retransmission of any unacked stanzas. The
            stream is then in running state.
            """

            if self.running:
                raise RuntimeError("Cannot resume Stream Management while"
                                   " StanzaStream is running")

            self._start_prepare(xmlstream, self.recv_stanza)
            try:
                response = yield from protocol.send_and_wait_for(
                    xmlstream,
                    [
                        nonza.SMResume(previd=self.sm_id,
                                       counter=self._sm_inbound_ctr)
                    ],
                    [
                        nonza.SMResumed,
                        nonza.SMFailed
                    ]
                )

                if isinstance(response, nonza.SMFailed):
                    xmlstream.stanza_parser.remove_class(
                        nonza.SMRequest)
                    xmlstream.stanza_parser.remove_class(
                        nonza.SMAcknowledgement)
                    self.stop_sm()
                    raise errors.StreamNegotiationFailure(
                        "Server rejected SM resumption")

                self._resume_sm(response.counter)
            except:  # NOQA
                self._start_rollback(xmlstream)
                raise
            self._start_commit(xmlstream)

        def _stop_sm(self):
            """
            Version of :meth:`stop_sm` which can be called during startup.
            """
            if not self.sm_enabled:
                raise RuntimeError("Stream Management is not enabled")

            self._logger.info("stopping SM stream")
            self._sm_enabled = False
            del self._sm_outbound_base
            del self._sm_inbound_ctr
            for token in self._sm_unacked_list:
                token._set_state(StanzaState.SENT_WITHOUT_SM)
            del self._sm_unacked_list

            self._destroy_stream_state(ConnectionError(
                "stream management disabled"
            ))

        def stop_sm(self):
            """
            Disable stream management on the stream.

            Attempting to call this method while the stream is running or without
            stream management enabled results in a :class:`RuntimeError`.

            Any sent stanzas which have not been acked by the remote yet are put
            into :attr:`StanzaState.SENT_WITHOUT_SM` state.
            """
            if self.running:
                raise RuntimeError("Cannot stop Stream Management while"
                                   " StanzaStream is running")
            return self._stop_sm()

        def sm_ack(self, remote_ctr):
            """
            Process the remote stanza counter `remote_ctr`. Any acked stanzas are
            dropped from :attr:`sm_unacked_list` and put into
            :attr:`StanzaState.ACKED` state and the counters are increased
            accordingly.

            If called with an erroneous remote stanza counter
            :class:`.errors.StreamNegotationFailure` will be raised.

            Attempting to call this without Stream Management enabled results in a
            :class:`RuntimeError`.
            """

            if not self._sm_enabled:
                raise RuntimeError("Stream Management is not enabled")

            self._logger.debug("sm_ack(%d)", remote_ctr)
            to_drop = (remote_ctr - self._sm_outbound_base) & 0xffffffff
            self._logger.debug("sm_ack: to drop %d, unacked: %d",
                               to_drop, len(self._sm_unacked_list))
            if to_drop > len(self._sm_unacked_list):
                raise errors.StreamNegotiationFailure(
                    "acked more stanzas than have been sent "
                    "(outbound_base={}, remote_ctr={})".format(
                        self._sm_outbound_base,
                        remote_ctr
                    )
                )

            acked = self._sm_unacked_list[:to_drop]
            del self._sm_unacked_list[:to_drop]
            self._sm_outbound_base = remote_ctr

            if acked:
                self._logger.debug("%d stanzas acked by remote", len(acked))
            for token in acked:
                token._set_state(StanzaState.ACKED)

        @asyncio.coroutine
        def send_iq_and_wait_for_reply(self, iq, *,
                                       timeout=None):
            """
            Send an IQ stanza `iq` and wait for the response. If `timeout` is not
            :data:`None`, it must be the time in seconds for which to wait for a
            response.

            If the response is a ``"result"`` IQ, the value of the
            :attr:`~aioxmpp.IQ.payload` attribute is returned. Otherwise,
            the exception generated from the :attr:`~aioxmpp.IQ.error`
            attribute is raised.

            .. seealso::

               :meth:`register_iq_response_future` and
               :meth:`send_and_wait_for_sent` for other cases raising exceptions.

            .. deprecated:: 0.8

               This method will be removed in 1.0. Use :meth:`send` instead.

            .. versionchanged:: 0.8

               On a timeout, :class:`TimeoutError` is now raised instead of
               :class:`asyncio.TimeoutError`.

            """
            warnings.warn(
                r"send_iq_and_wait_for_reply is deprecated and will be removed in"
                r" 1.0",
                DeprecationWarning,
                stacklevel=1,
            )
            return (yield from self.send(iq, timeout=timeout))

        @asyncio.coroutine
        def send_and_wait_for_sent(self, stanza):
            """
            Send the given `stanza` over the given :class:`StanzaStream` `stream`.

            .. deprecated:: 0.8

               This method will be removed in 1.0. Use :meth:`send` instead.
            """
            warnings.warn(
                r"send_and_wait_for_sent is deprecated and will be removed in 1.0",
                DeprecationWarning,
                stacklevel=1,
            )
            yield from self._enqueue(stanza)

        @asyncio.coroutine
        def _send_immediately(self, stanza, *, timeout=None, cb=None):
            """
            Send a stanza without waiting for the stream to be ready to send
            stanzas.

            This is only useful from within :class:`aioxmpp.node.Client` before
            the stream is fully established.
            """
            stanza.autoset_id()
            self._logger.debug("sending %r and waiting for it to be sent",
                               stanza)

            if not isinstance(stanza, stanza_.IQ) or stanza.type_.is_response:
                if cb is not None:
                    raise ValueError(
                        "cb not supported with non-IQ non-request stanzas"
                    )
                yield from self._enqueue(stanza)
                return

            # we use the long way with a custom listener instead of a future here
            # to ensure that the callback is called synchronously from within the
            # queue handling loop.
            # we need that to ensure that the strong ordering guarantees reach the
            # `cb` function.

            fut = asyncio.Future()

            def nested_cb(task):
                """
                This callback is used to handle awaitables returned by the `cb`.
                """
                nonlocal fut
                if task.exception() is None:
                    fut.set_result(task.result())
                else:
                    fut.set_exception(task.exception())

            def handler_ok(stanza):
                """
                This handler is invoked synchronously by
                :meth:`_process_incoming_iq` (via
                :class:`aioxmpp.callbacks.TagDispatcher`) for response stanzas
                (including error stanzas).
                """
                nonlocal fut
                if fut.cancelled():
                    return

                if cb is not None:
                    try:
                        nested_fut = cb(stanza)
                    except Exception as exc:
                        fut.set_exception(exc)
                    else:
                        if nested_fut is not None:
                            nested_fut.add_done_callback(nested_cb)
                            return

                # we can’t even use StanzaErrorAwareListener because we want to
                # forward error stanzas to the cb too...
                if stanza.type_.is_error:
                    fut.set_exception(stanza.error.to_exception())
                else:
                    fut.set_result(stanza.payload)

            def handler_error(exc):
                """
                This handler is invoked synchronously by
                :meth:`_process_incoming_iq` (via
                :class:`aioxmpp.callbacks.TagDispatcher`) for response errors (
                such as parsing errors, connection errors, etc.).
                """
                nonlocal fut
                if fut.cancelled():
                    return
                fut.set_exception(exc)

            listener = callbacks.OneshotTagListener(
                handler_ok,
                handler_error,
            )

            self._iq_response_map.add_listener(
                (stanza.to, stanza.id_),
                listener,
            )

            try:
                yield from self._enqueue(stanza)
            except Exception:
                listener.cancel()
                raise

            if not timeout:
                reply = yield from fut
            else:
                try:
                    reply = yield from asyncio.wait_for(
                        fut,
                        timeout=timeout
                    )
                except asyncio.TimeoutError:
                    raise TimeoutError
            return reply

        @asyncio.coroutine
        def send(self, stanza, timeout=None, *, cb=None):
            """
            Deprecated alias of :meth:`aioxmpp.Client.send`.

            This is only available on streams owned by a :class:`aioxmpp.Client`.

            .. deprecated:: 0.10
            """
            raise NotImplementedError("only available on streams owned by a Client")

    @contextlib.contextmanager
    def iq_handler(stream, type_, payload_cls, coro):
        """
        Context manager to temporarily register a coroutine to handle IQ requests
        on a :class:`StanzaStream`.

        :param stream: Stanza stream to register the coroutine at
        :type stream: :class:`StanzaStream`
        :param type_: IQ type to react to (must be a request type).
        :type type_: :class:`~aioxmpp.IQType`
        :param payload_cls: Payload class to react to (subclass of
                            :class:`~xso.XSO`)
        :type payload_cls: :class:`~.XMLStreamClass`
        :param coro: Coroutine to register

        The coroutine is registered when the context is entered and unregistered
        when the context is exited. Running coroutines are not affected by exiting
        the context manager.

        .. versionadded:: 0.8
        """

        stream.register_iq_request_handler(
            type_,
            payload_cls,
            coro,
        )
        try:
            yield
        finally:
            stream.unregister_iq_request_handler(type_, payload_cls)

    @contextlib.contextmanager
    def message_handler(stream, type_, from_, cb):
        """
        Context manager to temporarily register a callback to handle messages on a
        :class:`StanzaStream`.

        :param stream: Stanza stream to register the coroutine at
        :type stream: :class:`StanzaStream`
        :param type_: Message type to listen for, or :data:`None` for a wildcard
                      match.
        :type type_: :class:`~.MessageType` or :data:`None`
        :param from_: Sender JID to listen for, or :data:`None` for a wildcard
                      match.
        :type from_: :class:`~aioxmpp.JID` or :data:`None`
        :param cb: Callback to register

        The callback is registered when the context is entered and unregistered
        when the context is exited.

        .. versionadded:: 0.8
        """

        stream.register_message_callback(
            type_,
            from_,
            cb,
        )
        try:
            yield
        finally:
            stream.unregister_message_callback(
                type_,
                from_,
            )

    @contextlib.contextmanager
    def presence_handler(stream, type_, from_, cb):
        """
        Context manager to temporarily register a callback to handle presence
        stanzas on a :class:`StanzaStream`.

        :param stream: Stanza stream to register the coroutine at
        :type stream: :class:`StanzaStream`
        :param type_: Presence type to listen for.
        :type type_: :class:`~.PresenceType`
        :param from_: Sender JID to listen for, or :data:`None` for a wildcard
                      match.
        :type from_: :class:`~aioxmpp.JID` or :data:`None`.
        :param cb: Callback to register

        The callback is registered when the context is entered and unregistered
        when the context is exited.

        .. versionadded:: 0.8
        """

        stream.register_presence_callback(
            type_,
            from_,
            cb,
        )
        try:
            yield
        finally:
            stream.unregister_presence_callback(
                type_,
                from_,
            )

    _Undefined = object()

    def stanza_filter(filter_, func, order=_Undefined):
        """
        This is a deprecated alias of
        :meth:`aioxmpp.callbacks.Filter.context_register`.

        .. versionadded:: 0.8

        .. deprecated:: 0.9
        """
        if order is not _Undefined:
            return filter_.context_register(func, order)
        else:
            return filter_.context_register(func)