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<div class="section" id="add-an-event">
<span id="add-event"></span><span id="index-0"></span>
<div class="line-block">
<div class="line">Sometimes waiting for the completion of a task is not good enough.</div>
<div class="line">If a task is producing several results, another task may start as</div>
<div class="line">soon as the first results are ready.</div>
<div class="line">For that, ecFlow introduces the concept of <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-event"><em class="xref std std-term">event</em></a>&#8216;s.</div>
</div>
<div class="line-block">
<div class="line">An <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-event"><em class="xref std std-term">event</em></a> is a message that a task will report to ECF while</div>
<div class="line">it is running.</div>
</div>
<p>Events have names and a <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-task"><em class="xref std std-term">task</em></a> can set several of them:</p>
<div class="highlight-python"><pre># Definition of the suite test.
suite test
   edit ECF_INCLUDE "$HOME/course"
   edit ECF_HOME    "$HOME/course"
   family f1
     edit SLEEP 20
     task t1
     task t2
         trigger t1 eq complete
         event a
         event b
     task t3
         trigger t2:a
     task t4
         trigger t2:b
   endfamily
endsuite</pre>
</div>
<p>In python this would be like:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="c">#!/usr/bin/env python2.5</span>
<span class="kn">import</span> <span class="nn">os</span>
<span class="kn">import</span> <span class="nn">ecflow</span> 

<span class="k">def</span> <span class="nf">create_family_f1</span><span class="p">():</span>
    <span class="n">f1</span> <span class="o">=</span> <span class="n">ecflow</span><span class="o">.</span><span class="n">Family</span><span class="p">(</span><span class="s">&quot;f1&quot;</span><span class="p">)</span>
    <span class="n">f1</span><span class="o">.</span><span class="n">add_variable</span><span class="p">(</span><span class="s">&quot;SLEEP&quot;</span><span class="p">,</span><span class="mi">20</span><span class="p">)</span>
    <span class="n">f1</span><span class="o">.</span><span class="n">add_task</span><span class="p">(</span><span class="s">&quot;t1&quot;</span><span class="p">)</span>
    <span class="n">t2</span> <span class="o">=</span> <span class="n">f1</span><span class="o">.</span><span class="n">add_task</span><span class="p">(</span><span class="s">&quot;t2&quot;</span><span class="p">)</span>  
    <span class="n">t2</span><span class="o">.</span><span class="n">add_trigger</span><span class="p">(</span><span class="s">&quot;t1 eq complete&quot;</span><span class="p">)</span> 
    <span class="n">t2</span><span class="o">.</span><span class="n">add_event</span><span class="p">(</span><span class="s">&quot;a&quot;</span><span class="p">)</span>
    <span class="n">t2</span><span class="o">.</span><span class="n">add_event</span><span class="p">(</span><span class="s">&quot;b&quot;</span><span class="p">)</span>
    <span class="n">t3</span> <span class="o">=</span> <span class="n">f1</span><span class="o">.</span><span class="n">add_task</span><span class="p">(</span><span class="s">&quot;t3&quot;</span><span class="p">)</span>
    <span class="n">t3</span><span class="o">.</span><span class="n">add_trigger</span><span class="p">(</span><span class="s">&quot;t2:a&quot;</span><span class="p">)</span>  
    <span class="n">t4</span> <span class="o">=</span> <span class="n">f1</span><span class="o">.</span><span class="n">add_task</span><span class="p">(</span><span class="s">&quot;t4&quot;</span><span class="p">)</span>
    <span class="n">t4</span><span class="o">.</span><span class="n">add_trigger</span><span class="p">(</span><span class="s">&quot;t2:b&quot;</span><span class="p">)</span>  
    <span class="k">return</span> <span class="n">f1</span>

<span class="n">defs</span> <span class="o">=</span> <span class="n">ecflow</span><span class="o">.</span><span class="n">Defs</span><span class="p">(</span><span class="s">&quot;test.def&quot;</span><span class="p">)</span>
<span class="n">suite</span> <span class="o">=</span> <span class="n">defs</span><span class="o">.</span><span class="n">add_suite</span><span class="p">(</span><span class="s">&quot;test&quot;</span><span class="p">)</span>
<span class="n">suite</span><span class="o">.</span><span class="n">add_variable</span><span class="p">(</span><span class="s">&quot;ECF_INCLUDE&quot;</span><span class="p">,</span><span class="n">os</span><span class="o">.</span><span class="n">getenv</span><span class="p">(</span><span class="s">&quot;HOME&quot;</span><span class="p">)</span> <span class="o">+</span> <span class="s">&quot;/course&quot;</span><span class="p">)</span>
<span class="n">suite</span><span class="o">.</span><span class="n">add_variable</span><span class="p">(</span><span class="s">&quot;ECF_HOME   &quot;</span><span class="p">,</span><span class="n">os</span><span class="o">.</span><span class="n">getenv</span><span class="p">(</span><span class="s">&quot;HOME&quot;</span><span class="p">)</span> <span class="o">+</span> <span class="s">&quot;/course&quot;</span><span class="p">)</span>

<span class="n">suite</span><span class="o">.</span><span class="n">add_family</span><span class="p">(</span> <span class="n">create_family_f1</span><span class="p">()</span> <span class="p">)</span>
</pre></div>
</div>
<div class="line-block">
<div class="line">To notify <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-ecf-server"><em class="xref std std-term">ecf_server</em></a>, the task <strong>t2</strong> must call</div>
<div class="line"><a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-ecf-client"><em class="xref std std-term">ecf_client</em></a> &#8211;event which is one of the <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-child-command"><em class="xref std std-term">child command</em></a>&#8216;s</div>
</div>
<div class="highlight-python"><pre>%include &lt;head.h&gt;
echo "I will now sleep for %SLEEP% seconds"
sleep %SLEEP%
ecf_client --event a       # Set the first event
sleep %SLEEP%              # Sleep a bit more
ecf_client --event b       # Set the second event
sleep %SLEEP%              # A last nap...
%include &lt;tail.h&gt;</pre>
</div>
<p>What to do:</p>
<ol class="arabic simple">
<li>Edit the definition or python file to add the modifications.</li>
<li>Edit <tt class="file docutils literal"><span class="pre">t2.ecf</span></tt> to call <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-ecf-client"><em class="xref std std-term">ecf_client</em></a> &#8211;event.</li>
<li>Copy <tt class="file docutils literal"><span class="pre">t1.ecf</span></tt> to <tt class="file docutils literal"><span class="pre">t3.ecf</span></tt> and <tt class="file docutils literal"><span class="pre">t4.ecf</span></tt></li>
<li>Load the definition again.</li>
<li>Observe the tasks in <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-ecflowview"><em class="xref std std-term">ecFlowview</em></a>.</li>
<li>See the triggers by selecting <strong>t3</strong> and clicking on the icon <img alt="triggers" src="../../../_images/triggers.jpg" /></li>
<li>See the triggers by selecting <strong>t2</strong> and click on <strong>Dependencies</strong></li>
</ol>
</div>