path: root/lib/megaco/doc/src/megaco_debug.xml

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<chapter>
  <header>
    <copyright>
      <year>2000</year><year>2013</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>Testing and tools</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_debug.xml</file>
  </header>

  <section>
    <title>Tracing</title>
    <p>We have instrumented our code in order to enable
      tracing. Running the application with tracing deactivated,
      causes a negligible performance overhead (an external call to a
      function which returns an atom). Activation of tracing does not
      require any recompilation of the code, since we rely on
      Erlang/OTP's built in support for dynamic trace activation. In
      our case tracing of calls to a given external function.</p>
    <p>Event traces can be viewed in a generic message sequence chart
      tool, <c>et</c>, or as standard output (events are written to stdio). </p>
    <p>See <seealso marker="megaco#enable_trace">enable_trace</seealso>, 
      <seealso marker="megaco#disable_trace">disable_trace</seealso> and
      <seealso marker="megaco#set_trace">set_trace</seealso> for
      more info. </p>
  </section>

  <section>
    <title>Measurement and transformation</title>
    <p>We have included some simple tool(s) for codec measurement (meas),
      performance tests (mstone1 and mstone2) and message transformation.</p>
    <p>The tool(s) are located in the example/meas directory.</p>

    <section>
      <title>Requirement</title>
      <list type="bulleted">
        <item>
          <p>Erlang/OTP, version R13B01 or later.</p>
        </item>
        <item>
          <p>Version 3.11 or later of <em>this</em> application.</p>
        </item>
        <item>
          <p>Version 1.6.10 or later of the <em>asn1</em> application. </p>
        </item>
        <item>
          <p>The flex libraries. Without it, the flex powered codecs cannot 
            be used.</p>
        </item>
      </list>
    </section>

    <section>
      <title>Meas results</title>
      <p>The results from the measurement run (meas) is four 
        excel-compatible textfiles: </p>
      <list type="bulleted">
        <item>
          <p>decode_time.xls  -&gt; Decoding result</p>
        </item>
        <item>
          <p>encode_time.xls  -&gt; Encoding result</p>
        </item>
        <item>
          <p>total_time.xls   -&gt; Total (Decoding+encoding) result</p>
        </item>
        <item>
          <p>message_size.xls -&gt; Message size</p>
        </item>
      </list>
    </section>

    <section>
      <title>Instruction</title>
      <p>The tool contain four things:
        </p>
      <list type="bulleted">
        <item>
          <p>The transformation module</p>
        </item>
        <item>
          <p>The measurement (meas) module(s)</p>
        </item>
        <item>
          <p>The mstone (mstone1 and mstone2) module(s)</p>
        </item>
        <item>
          <p>The basic message file</p>
        </item>
      </list>

      <section>
        <title>Message Transformation</title>
        <p>The messages used by the different tools are contained in 
          single message package file (see below for more info). The messages
          in this file is encoded with just one codec. During 
          measurement initiation, the messages are read and then transformed to all
          codec formats used in the measurement. </p>
        <p>The message transformation is done by the transformation module.
          It is used to transform a set of messages encoded with one codec 
          into the other base codec's.</p>
      </section>

      <section>
        <title>Measurement(s)</title>
        <p>There are two different measurement tools: </p>
        <list type="bulleted">
          <item>
            <p><em>meas</em>: </p>
            <p>Used to perform codec measurements. That is, to see what 
              kind of performance can be expected by the different codecs 
              provided by the megaco application. </p>
            <p>The measurement is done by iterating over the decode/encode 
              function for approx 2 seconds per message and counting 
              the number of decodes/encodes.</p>
            <p>Is best run by modifying the meas.sh.skel skeleton script
              provided by the tool.</p>
            <p>To run it manually do the following: </p>
              <code type="none"><![CDATA[
        % erl -pa <path-megaco-ebin-dir> -pa <path-to-meas-module-dir>
        Erlang (BEAM) emulator version 5.6 [source]

        Eshell V5.7.1  (abort with ^G)
        1> megaco_codec_meas:start().
        ...
        2> halt().
        ]]></code>
            <p>or to make it even easier, assuming a measure shall be 
              done on all the codecs (as above):</p>
              <code type="none"><![CDATA[
        % erl -noshell -pa <path-megaco-ebin-dir> \\
              -pa <path-to-meas-module-dir> \\
              -s megaco_codec_meas -s init stop
        ]]></code>
            <p>When run as above (this will take some time), the measurement 
              process is done as follows:</p>
        <pre>
For each codec:
    For each message:
        Read the message from the file
            Detect message version
            Measure decode
                Measure encode
          Write results, encode, decode and total, to file
        </pre>
          </item>

          <item>
            <p><em>mstone1 and mstone2</em>: </p>
            <p>These are two different SMP performance monitoring tool(s). </p>
            <p><em>mstone1</em> creates a process for each codec config supported by 
              the megaco application and let them run for a specific 
              time (all at the same time), encoding and decoding 
              megaco messages. The number of messages processed in total 
              is the mstone1(1) value. </p>
            <p>There are different ways to run the mstone1 tool, e.g. with or without 
              the use of drivers, with <em>only</em> flex-empowered configs. </p>
            <p>Is best run by modifying the mstone1.sh.skel skeleton script
              provided by the tool.</p>
            <p>The <em>mstone2</em> is similar to the <em>mstone1</em> tool,
              but in this case, each created process makes only <em>one</em> run 
              through the messages and then exits. A soon as a process exits,
              a new process (with the same config and messages) is created to takes 
              its place. 
              The number of messages processed in total 
              is the mstone2(1) value. </p>
          </item>
        </list>

        <p>Both these tools use the message package (time_test.msgs) provided
          with the tool(s), although it can run on any message package as long as
          it has the same structure. </p>
      </section>

      <section>
        <title>Message package file</title>
        <p>This is simply an erlang compatible text-file with the following 
          structure: <c>{codec_name(), messages_list()}</c>. </p>

<pre>
codec_name() = pretty | compact | ber | per | erlang      (how the messages are encoded)
messages_list() = [{message_name(), message()}]
message_name() = atom()
message() = binary()
</pre>

        <p>The codec name is the name of the codec with which all messages in
          the <c>message_list()</c> has been encoded. </p>

        <p>This file can be <c>exported</c> to a file structure by calling the 
          <seealso marker="megaco_codec_transform#export_messages">export_messages</seealso>
          function. This can be usefull if a measurement shall be done with
          an external tool. Exporting the messages creates a directory tree 
          with the following structure:
          </p>
        <code type="none"><![CDATA[
<message package>/pretty/<message-files>
                  compact/
                  per/
                  ber/<message-files>
                  erlang/
        ]]></code>
        <p>The file includes both version 1, 2 and version 3 messages.</p>
      </section>
    </section>

    <section>
      <title>Notes</title>

      <section>
        <title>Binary codecs</title>
        <p>There are two basic ways to use the binary encodings: 
          With package related name and termination id transformation
          (the 'native' encoding config) or without. This transformation 
          converts package related names and termination id's to a more 
          convenient internal form (equivalent with the decoded text message).</p>
        <p>The transformation is done _after_ the actual decode has been 
          done.</p>
        <p>Furthermore, it is possible to make use of a linked in driver that 
          performs some of the decode/encode, decode for ber and encode for per 
          (the 'driver' encoding config).</p>
        <p>Therefor in the tests, binary codecs are tested with four 
          different encoding configs to determine exactly how the
          different options effect the performance: with transformation and 
          without driver ([]), without transformation and without driver 
          ([native]), with transformation and with driver ([driver]) and 
          finally without transformation and with driver ([driver,native]).</p>
      </section>

      <section>
        <title>Included test messages</title>
        <p>Some of these messages are ripped from the call flow examples 
          in an old version of the RFC and others are created to test
          a specific feature of megaco. </p>
      </section>

      <section>
        <title>Measurement tool directory name</title>
        <p>Be sure <em>not</em> no name the directory containing the measurement
          binaries starting with 'megaco-', e.g. megaco-meas. This will
          confuse the erlang application loader (erlang applications
          are named, e.g. megaco-1.0.2).</p>
      </section>
    </section>
  </section>
</chapter>