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  <header>
    <copyright>
      <year>2000</year><year>2021</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      Licensed under the Apache License, Version 2.0 (the "License");
      you may not use this file except in compliance with the License.
      You may obtain a copy of the License at
 
          http://www.apache.org/licenses/LICENSE-2.0

      Unless required by applicable law or agreed to in writing, software
      distributed under the License is distributed on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      See the License for the specific language governing permissions and
      limitations under the License.
    
    </legalnotice>

    <title>megaco_udp</title>
    <prepared>Lars Thors&eacute;n</prepared>
    <responsible>Lars Thors&eacute;n</responsible>
    <docno></docno>
    <approved>Lars Thors&eacute;n</approved>
    <checked></checked>
    <date>2007-06-15</date>
    <rev>%VSN%</rev>
    <file>megaco_udp.xml</file>
  </header>
  <module since="">megaco_udp</module>
  <modulesummary>Interface module to UDP transport protocol for Megaco/H.248.</modulesummary>
  <description>
    <p>This module contains the public interface to the UDP/IP version
      transport protocol for Megaco/H.248.</p>
  </description>
  <funcs>
    <func>
      <name since="">start_transport() -> {ok, TransportRef}</name>
      <fsummary></fsummary>
      <type>
        <v>TransportRef = pid()</v>
      </type>
      <desc>
        <p>This function is used for starting the UDP/IP transport service.
          Use exit(TransportRef, Reason) to stop the transport service.</p>
      </desc>
    </func>
    <func>
      <name since="">open(TransportRef, OptionList) ->  {ok, Handle, ControlPid} |  {error, Reason}</name>
      <fsummary></fsummary>
      <type>
        <v>TransportRef = pid() | regname()</v>
        <v>OptionList = [option()]</v>
	<v>option() = {port,           integer()} |
	              {options,        list()} |
	              {receive_handle, receive_handle()} |
	              {module,         atom()}  |
	              {inet_backend,   default | inet | socket}</v>
        <v>Handle = socket_handle()</v>
        <v>receive_handle() = term()</v>
        <v>ControlPid = pid()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
	<p>This function is used to open an UDP/IP socket.</p>
	<taglist>
	  <tag><c><![CDATA[module]]></c></tag>
	  <item>
	    <p>The option makes it possible for the user to provide
	    their own callback module.
	    The functions <c><![CDATA[receive_message/4]]></c> or
	    <c><![CDATA[process_received_message/4]]></c>
	    of this module is called when a new message is received.
	    Which one depends on the size of the message: </p>
	    <taglist>
	      <tag><c><![CDATA[small]]></c></tag>
	      <item><p>receive_message</p></item>
	      <tag><c><![CDATA[large]]></c></tag>
	      <item><p>process_received_message</p></item>
	    </taglist>
	    <p>Default value is <em>megaco</em>.</p>
	  </item>
	</taglist>
      </desc>
    </func>
    <func>
      <name since="">close(Handle, Msg) -> ok</name>
      <fsummary></fsummary>
      <type>
        <v>Handle = socket_handle()</v>
        <v>Msg</v>
      </type>
      <desc>
        <p>This function is used for closing an active UDP socket.</p>
      </desc>
    </func>
    <func>
      <name since="">socket(Handle) -> Socket</name>
      <fsummary></fsummary>
      <type>
        <v>Handle = socket_handle()</v>
        <v>Socket = inet_socket()</v>
      </type>
      <desc>
        <p>This function is used to convert a socket_handle() to
          a inet_socket(). inet_socket() is a plain socket,
          see the inet module for more info.</p>
      </desc>
    </func>
    <func>
      <name since="">create_send_handle(Handle, Host, Port) -> send_handle()</name>
      <fsummary></fsummary>
      <type>
        <v>Handle = socket_handle()</v>
        <v>Host = {A,B,C,D} | string()</v>
        <v>Port = integer()</v>
      </type>
      <desc>
        <p>Creates a send handle from a transport handle.  The send
          handle is intended to be used by megaco_udp:send_message/2.</p>
      </desc>
    </func>
    <func>
      <name since="">send_message(SendHandle, Msg) -> ok</name>
      <fsummary></fsummary>
      <type>
        <v>SendHandle = send_handle()</v>
        <v>Message = binary() | iolist()</v>
      </type>
      <desc>
        <p>Sends a message on a socket. The send handle is obtained by
          megaco_udp:create_send_handle/3. Increments the NumOutMessages
          and NumOutOctets counters if message successfully sent. In case
          of a failure to send, the NumErrors counter is <em>not</em>
          incremented. This is done elsewhere in the megaco app.</p>
      </desc>
    </func>
    <func>
      <name since="">block(Handle) -> ok</name>
      <fsummary></fsummary>
      <type>
        <v>Handle = socket_handle()</v>
      </type>
      <desc>
        <p>Stop receiving incoming messages on the socket.</p>
      </desc>
    </func>
    <func>
      <name since="">unblock(Handle) -> ok</name>
      <fsummary></fsummary>
      <type>
        <v>Handle = socket_handle()</v>
      </type>
      <desc>
        <p>Starting to receive incoming messages from the socket again.</p>
        <marker id="upgrade_receive_handle"></marker>
      </desc>
    </func>
    <func>
      <name since="">upgrade_receive_handle(ControlPid, NewHandle) -> ok</name>
      <fsummary></fsummary>
      <type>
        <v>ControlPid = pid()</v>
        <v>NewHandle = receive_handle()</v>
        <v>receive_handle() = term()</v>
      </type>
      <desc>
        <p>Update the receive handle of the control process (e.g. after
          having changed protocol version).</p>
        <marker id="stats"></marker>
      </desc>
    </func>
    <func>
      <name since="">get_stats() -> {ok, TotalStats} | {error, Reason}</name>
      <name since="">get_stats(SendHandle) -> {ok, SendHandleStats} | {error, Reason}</name>
      <name since="">get_stats(SendHandle, Counter) -> {ok, CounterStats} | {error, Reason}</name>
      <fsummary></fsummary>
      <type>
        <v>TotalStats = [total_stats()]</v>
        <v>total_stats() = {send_handle(), [stats()]}</v>
        <v>SendHandle = send_handle()</v>
        <v>SendHandleStats = [stats()]</v>
        <v>Counter = udp_stats_counter()</v>
        <v>CounterStats = integer()</v>
        <v>stats() = {udp_stats_counter(), integer()}</v>
        <v>tcp_stats_counter() = medGwyGatewayNumInMessages |  medGwyGatewayNumInOctets | medGwyGatewayNumOutMessages | medGwyGatewayNumOutOctets | medGwyGatewayNumErrors</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Retreive the UDP related (SNMP) statistics counters.</p>
      </desc>
    </func>
    <func>
      <name since="">reset_stats() -> void()</name>
      <name since="">reset_stats(SendHandle) -> void()</name>
      <fsummary></fsummary>
      <type>
        <v>SendHandle = send_handle()</v>
      </type>
      <desc>
        <p>Reset all TCP related (SNMP) statistics counters.</p>
      </desc>
    </func>
  </funcs>

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