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<img alt="Erlang logo" src="../../../../doc/erlang-logo.png"><br><small><a href="users_guide.html">User's Guide</a><br><a href="index.html">Reference Manual</a><br><a href="release_notes.html">Release Notes</a><br><a href="../pdf/megaco-3.16.0.2.pdf">PDF</a><br><a href="../../../../doc/index.html">Top</a></small><p><strong>Megaco/H.248</strong><br><strong>User's Guide</strong><br><small>Version 3.16.0.2</small></p>
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<li title="A simple Media Gateway Controller"><a href="megaco_examples.html#id66572">A simple Media Gateway Controller</a></li>
<li title="A simple Media Gateway"><a href="megaco_examples.html#id66620">A simple Media Gateway</a></li>
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<h1>6 Implementation examples</h1>
<h3><a name="id66572">6.1
A simple Media Gateway Controller</a></h3>
<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>
<div class="example"><pre>
cd megaco/examples/simple
erl -pa ../../../megaco/ebin -s megaco_filter -s megaco
megaco_simple_mgc:start().
</pre></div>
<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>
<h3><a name="id66620">6.2
A simple Media Gateway</a></h3>
<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>
<div class="example"><pre>
cd megaco/examples/simple
erl -pa ../../../megaco/ebin -s megaco_filter -s megaco
megaco_simple_mg:start().
</pre></div>
<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>
<div class="example"><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></div>
<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>
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