<?xml version="1.0" ?>
<node name="/Channel_Interface_Hold" xmlns:tp="http://telepathy.freedesktop.org/wiki/DbusSpec#extensions-v0">
  <tp:copyright> Copyright (C) 2005-2008 Collabora Limited </tp:copyright>
  <tp:copyright> Copyright (C) 2005-2008 Nokia Corporation </tp:copyright>
  <tp:copyright> Copyright (C) 2006 INdT </tp:copyright>
  <tp:license xmlns="http://www.w3.org/1999/xhtml">
This library 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 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  </tp:license>

  <interface name="org.freedesktop.Telepathy.Channel.Interface.Hold">
    <tp:xor-requires>
      <tp:requires interface="org.freedesktop.Telepathy.Channel.Type.StreamedMedia"/>
      <tp:requires interface="org.freedesktop.Telepathy.Channel.Type.Call1"/>
      <tp:requires interface="org.freedesktop.Telepathy.Call1.Content"/>
    </tp:xor-requires>
    <tp:changed version="0.17.4">first API-stable version</tp:changed>

    <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
      <p>Interface for channels where you may put the channel on hold.
        This only makes sense for channels where
        you are streaming media to or from the members. (To see whether the
        other participant has put you on hold, see <tp:dbus-ref
          namespace="org.freedesktop.Telepathy.Channel.Interface"
        >CallState</tp:dbus-ref>.)</p>

      <p>If you place a channel on hold, this indicates that you do not wish
        to be sent media streams by any of its members and will be ignoring
        any media streams you continue to receive. It also requests that the
        connection manager free up any resources that are only needed for
        an actively used channel (e.g. in a GSM or PBX call, it will be
        necessary to place an active call on hold before you can start
        another call).</p>

      <p>This can also be used for putting a single Content on hold, if the
        protocol supports it (This interface is in the Channel namespace for
        historical reasons).</p>
    </tp:docstring>

    <method name="GetHoldState" tp:name-for-bindings="Get_Hold_State">
      <tp:docstring>
        Return whether the local user has placed the channel on hold.
      </tp:docstring>

      <arg name="HoldState" direction="out" type="u"
          tp:type="Local_Hold_State">
        <tp:docstring>
          The state of the channel
        </tp:docstring>
      </arg>

      <arg name="Reason" direction="out" type="u"
          tp:type="Local_Hold_State_Reason">
        <tp:docstring>
          The reason why the channel is in that state
        </tp:docstring>
      </arg>
    </method>

    <signal name="HoldStateChanged" tp:name-for-bindings="Hold_State_Changed">
      <tp:docstring>
        Emitted to indicate that the hold state has changed for this channel.
        This may occur as a consequence of you requesting a change with
        <tp:member-ref>RequestHold</tp:member-ref>, or the state changing as a
        result of a request from
        another process.
      </tp:docstring>

      <arg name="HoldState" type="u" tp:type="Local_Hold_State">
        <tp:docstring>
          The state of the channel
        </tp:docstring>
      </arg>

      <arg name="Reason" type="u" tp:type="Local_Hold_State_Reason">
        <tp:docstring>
          The reason for the state change
        </tp:docstring>
      </arg>
    </signal>

    <tp:enum name="Local_Hold_State" type="u">
      <tp:docstring>
        The hold state of a channel.
      </tp:docstring>

      <tp:enumvalue value="0" suffix="Unheld">
        <tp:docstring>
          All streams are unheld (the call is active). New channels SHOULD
          have this hold state.
        </tp:docstring>
      </tp:enumvalue>

      <tp:enumvalue value="1" suffix="Held">
        <tp:docstring>
          All streams are held (the call is on hold)
        </tp:docstring>
      </tp:enumvalue>

      <tp:enumvalue value="2" suffix="Pending_Hold">
        <tp:docstring>
          The connection manager is attempting to move to state Held, but
          has not yet completed that operation. It is unspecified whether
          any, all or none of the streams making up the channel are on hold.
          Examining the Hold state of Call Contents (if applicable) may
          provide more useful information.
        </tp:docstring>
      </tp:enumvalue>

      <tp:enumvalue value="3" suffix="Pending_Unhold">
        <tp:docstring>
          The connection manager is attempting to move to state Unheld, but
          has not yet completed that operation. It is unspecified whether
          any, all or none of the streams making up the channel are on hold.
          Examining the Hold state of Call Contents (if applicable) may
          provide more useful information.
        </tp:docstring>
      </tp:enumvalue>
    </tp:enum>

    <tp:enum name="Local_Hold_State_Reason" type="u">
      <tp:docstring>
        The reason for a change to the Local_Hold_State. Clients MUST
        treat unknown values as equivalent to Local_Hold_State_Reason_None.
      </tp:docstring>

      <tp:enumvalue value="0" suffix="None">
        <tp:docstring>
          The reason cannot be described by any of the predefined values
          (connection managers SHOULD avoid this reason, but clients MUST
          handle it gracefully)
        </tp:docstring>
      </tp:enumvalue>

      <tp:enumvalue value="1" suffix="Requested">
        <tp:docstring>
          The change is in response to a user request
        </tp:docstring>
      </tp:enumvalue>

      <tp:enumvalue value="2" suffix="Resource_Not_Available">
        <tp:docstring>
          The change is because some resource was not available
        </tp:docstring>
      </tp:enumvalue>
    </tp:enum>

    <method name="RequestHold" tp:name-for-bindings="Request_Hold">
      <arg direction="in" name="Hold" type="b">
        <tp:docstring>
          A boolean indicating whether or not the channel should be on hold
        </tp:docstring>
      </arg>

      <tp:docstring xmlns="http://www.w3.org/1999/xhtml">
        <p>Request that the channel be put on hold (be instructed not to send
          any media streams to you) or be taken off hold.</p>

        <p>If the connection manager can immediately tell that the requested
          state change could not possibly succeed, this method SHOULD
          return the NotAvailable error. If the requested state is the
          same as the current state, this method SHOULD return successfully
          without doing anything.</p>

        <p>Otherwise, this method SHOULD immediately set the hold state to
          Local_Hold_State_Pending_Hold or Local_Hold_State_Pending_Unhold
          (as appropriate), emitting
          <tp:member-ref>HoldStateChanged</tp:member-ref> if this is a change,
          and return successfully.</p>

        <p>The eventual success or failure of the request is indicated by a
          subsequent HoldStateChanged signal, changing the hold state to
          Local_Hold_State_Held or Local_Hold_State_Unheld.</p>

        <p>If the channel has multiple streams, and the connection manager
          succeeds in changing the hold state of one stream but fails to
          change the hold state of another, it SHOULD attempt to revert
          all streams to their previous hold states.</p>

        <p>The following state transitions SHOULD be used, where
          appropriate:</p>

        <ul>
          <li>Successful hold:
            (Unheld, any reason) → (Pending_Hold, Requested) →
            (Held, Requested)
          </li>
          <li>Successful unhold:
            (Held, any reason) → (Pending_Unhold, Requested) →
            (Unheld, Requested)
          </li>
          <li>Attempting to unhold fails at the first attempt to acquire a
            resource:
            (Held, any reason) → (Pending_Unhold, Requested) →
            (Held, Resource_Not_Available)
          </li>
          <li>Attempting to unhold acquires one resource, but fails to acquire
            a second, and takes time to release the first:
            (Held, any reason) → (Pending_Unhold, Requested) →
            (Pending_Hold, Resource_Not_Available) →
            (Held, Resource_Not_Available)
          </li>
        </ul>
      </tp:docstring>

      <tp:possible-errors>
        <tp:error name="org.freedesktop.Telepathy.Error.Disconnected"/>
        <tp:error name="org.freedesktop.Telepathy.Error.NetworkError"/>
        <tp:error name="org.freedesktop.Telepathy.Error.NotAvailable">
          <tp:docstring>
            The requested hold state cannot be achieved; for example,
            if only a limited number of channels can be in the "not on hold"
            state, attempts to exceed this number will raise NotAvailable.
          </tp:docstring>
        </tp:error>
      </tp:possible-errors>
    </method>

  </interface>
</node>
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