Big-Data-HPC-Platform/docs/ECLScheduler/ECLScheduler.xml

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  <title>The ECL Scheduler</title>

  <bookinfo>
    <title>ECL Scheduler</title>

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      <surname>Boca Raton Documentation Team</surname>
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  <chapter>
    <title>The Ecl Scheduler</title>

    <sect1 role="nobrk">
      <title>Introduction</title>

      <para>The ECL Scheduler is a component process installed with the HPCC
      system platform. It typically starts with the platform.</para>

      <para>An interface to the scheduler is available through ECL Watch. The
      ECL Scheduler interface allows you to see a list of scheduled workunits.
      It can also trigger an event. An Event is a case-insensitive string
      constant naming the event to trap.</para>

      <para>A command line tool, <emphasis>scheduleadmin</emphasis> is
      available on the server installed in /opt/HPCCSystems/bin.</para>

      <sect2>
        <title>ECL Scheduling</title>

        <para>ECL Scheduling provides a means of automating processes within
        ECL code or to chain processes together to work in sequence. For
        example, you can write ECL code that watches a landing zone for the
        arrival of a file, and when it arrives, sprays it to Thor, processes
        it, builds an index, and then adds it to a superfile.</para>
      </sect2>

      <sect2>
        <title>How it Works</title>

        <para>ECL Scheduling is event-based. The ECL Scheduler monitors a
        Schedule list containing registered Workunits and Events and executes
        any Workunits associated with an Event when that Event is
        triggered.</para>

        <para>Your ECL Code can execute when an Event is triggered, or can
        trigger an Event. If you submit code containing a <emphasis
        role="bold">WHEN </emphasis>clause, the Event and Workunit registers
        in the Schedule list. When that Event triggers, the Workunit compiles
        and executes. When the Workunit completes, ECL Scheduler removes it
        from the Schedule list.</para>

        <para>For example, if you submit a Workunit using <emphasis
        role="bold">WHEN(‘Event1’,’MyEvent’, COUNT(2)) </emphasis>in the
        appropriate place, it will execute twice (the value of <emphasis
        role="bold">COUNT</emphasis>) before the ECL Scheduler removes it from
        the Schedule list and the Workunit is marked as completed.</para>
      </sect2>
    </sect1>
  </chapter>

  <xi:include href="ECLScheduler/ECLSched-Mods/ECLSchedComp.xml"
              xpointer="ECLSched_comp"
              xmlns:xi="http://www.w3.org/2001/XInclude" />

  <xi:include href="ECLScheduler/ECLSched-Mods/ECLSchedAdmin.xml"
              xpointer="ECLSched-Admin"
              xmlns:xi="http://www.w3.org/2001/XInclude" />

  <chapter>
    <title>ECL Usage</title>

    <para>The ECL Scheduler is a tool that can perform a specific action based
    on a specific event. The following functions can be viewed or manipulated
    in the scheduler.</para>

    <sect1 id="WHEN">
      <title>WHEN</title>

      <xi:include href="ECLLanguageReference/ECLR_mods/BltInFunc-WHEN.xml"
                  xpointer="SchWhen"
                  xmlns:xi="http://www.w3.org/2001/XInclude" />
    </sect1>

    <sect1 id="NOTIFY">
      <title>NOTIFY</title>

      <xi:include href="ECLLanguageReference/ECLR_mods/BltInFunc-NOTIFY.xml"
                  xpointer="SchNOTIFY"
                  xmlns:xi="http://www.w3.org/2001/XInclude" />
    </sect1>

    <sect1>
      <title>EVENT</title>

      <xi:include href="ECLLanguageReference/ECLR_mods/BltInFunc-EVENT.xml"
                  xpointer="SchEvent"
                  xmlns:xi="http://www.w3.org/2001/XInclude" />
    </sect1>

    <sect1>
      <title>CRON</title>

      <xi:include href="ECLLanguageReference/ECLR_mods/BltInFunc-CRON.xml"
                  xpointer="SchCRON"
                  xmlns:xi="http://www.w3.org/2001/XInclude" />
    </sect1>

    <sect1>
      <title>WAIT</title>

      <xi:include href="ECLLanguageReference/ECLR_mods/BltInFunc-WAIT.xml"
                  xpointer="SchWAIT"
                  xmlns:xi="http://www.w3.org/2001/XInclude" />
    </sect1>
  </chapter>

  <chapter>
    <title>DFU Monitoring and Events</title>

    <para>The following are supported methods for the ECL Scheduler included
    in the ECL Standard Library Reference.</para>

    <xi:include href="ECLStandardLibraryReference/SLR-Mods/MonitorFile.xml"
                xpointer="MonitorFile"
                xmlns:xi="http://www.w3.org/2001/XInclude" />

    <xi:include href="ECLStandardLibraryReference/SLR-Mods/MonitorLogicalFileName.xml"
                xpointer="MonitorLogicalFileName"
                xmlns:xi="http://www.w3.org/2001/XInclude" />
  </chapter>
</book>