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<chapter>
  <header>
    <copyright>
      <year>2000</year><year>2009</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      The contents of this file are subject to the Erlang Public License,
      Version 1.1, (the "License"); you may not use this file except in
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    <title>Implementation examples</title>
    <prepared>H&aring;kan Mattsson</prepared>
    <responsible>H&aring;kan Mattsson</responsible>
    <docno></docno>
    <approved>H&aring;kan Mattsson</approved>
    <checked></checked>
    <date>2007-06-15</date>
    <rev>%VSN%</rev>
    <file>megaco_examples.xml</file>
  </header>

  <section>
    <title>A simple Media Gateway Controller</title>
    <p>In megaco/examples/simple/megaco_simple_mgc.erl there is an
      example of a simple MGC that listens on both text and binary
      standard ports and is prepared to handle a Service Change
      Request message to arrive either via TCP/IP or UDP/IP. Messages
      received on the text port are decoded using a text decoder and
      messages received on the binary port are decoded using a binary
      decoder.</p>
    <p>The Service Change Reply is encoded in the same way as the
      request and sent back to the MG with the same transport
      mechanism UDP/IP or TCP/IP.</p>
    <p>After this initial service change message the connection
      between the MG and MGC is fully established and supervised.</p>
    <p>The MGC, with its four listeners, may be started with:</p>
    <pre>
      cd megaco/examples/simple
      erl -pa ../../../megaco/ebin -s megaco_filter -s megaco
      megaco_simple_mgc:start().
    </pre>
    <p>or simply 'gmake mgc'.</p>
    <p>The -s megaco_filter option to erl implies, the event tracing
      mechanism to be enabled and an interactive sequence chart tool
      to be started. This may be quite useful in order to visualize
      how your MGC interacts with the Megaco/H.248 protocol stack.</p>
    <p>The event traces may alternatively be directed to a file for
      later analyze. By default the event tracing is disabled, but it
      may dynamically be enabled without any need for re-compilation
      of the code.
      </p>
  </section>

  <section>
    <title>A simple Media Gateway</title>
    <p>In megaco/examples/simple/megaco_simple_mg.erl there is an
      example of a simple MG that connects to an MGC, sends a Service
      Change Request and waits synchronously for a reply.</p>
    <p>After this initial service change message the connection
      between the MG and MGC is fully established and supervised.</p>
    <p>Assuming that the MGC is started on the local host, four
      different MG's, using text over TCP/IP, binary over TCP/IP, text
      over UDP/IP and binary over UDP/IP may be started on the same
      Erlang node with:</p>
    <pre>
      cd megaco/examples/simple
      erl -pa ../../../megaco/ebin -s megaco_filter -s megaco
      megaco_simple_mg:start().
    </pre>
    <p>or simply 'gmake mg'.</p>
    <p>If you "only" want to start a single MG which tries to connect
      an MG on a host named "baidarka", you may use one of these
      functions (instead of the megaco_simple_mg:start/0 above):</p>
    <pre>
      megaco_simple_mg:start_tcp_text("baidarka", []).
      megaco_simple_mg:start_tcp_binary("baidarka", []).
      megaco_simple_mg:start_udp_text("baidarka", []).
      megaco_simple_mg:start_udp_binary("baidarka", []).
    </pre>
    <p>The -s megaco_filter option to erl implies, the event tracing
      mechanism to be enabled and an interactive sequence chart tool
      to be started. This may be quite useful in order to visualize
      how your MG interacts with the Megaco/H.248 protocol stack.</p>
    <p>The event traces may alternatively be directed to a file for
      later analyze. By default the event tracing is disabled, but it
      may dynamically be enabled without any need for re-compilation
      of the code.
      </p>
  </section>
</chapter>

