Big-Data-HPC-Platform/docs/ECLLanguageReference/ECLR_mods/WkFlo-OverView.xml

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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<sect1 id="Workflow_Overview">
  <title>Workflow Overview</title>

  <para>Workflow control within ECL is generally handled automatically by the
  system. It spots which processes can happen in parallel, when
  synchronization is required, and when processes must happen in series. These
  workflow services allow exceptions to the normal flow of execution to be
  specified by the programmer to give extra control (such as the FAILURE
  clause).</para>

  <para>Workflow operations are implicitly evaluated in a separate global
  scope from the code to which it is attached. Therefore, any values from the
  code to which it is attached (such as loop counters) are unavailable to the
  workflow service.</para>

  <para>It should also be noted that when a workflow operation is present within
  multiple SEQUENTIAL statements only the first instance will be evaluated.</para>

  <para>Example:</para>

  <programlisting>
Chesney := OUTPUT('"I am the one and only!" said Chesney')
        : SUCCESS(OUTPUT('"Oh yeah, prove it?"'));

SEQUENTIAL(
              OUTPUT('"I am Spartacus" said one from the mob'),
              Chesney
          );

SEQUENTIAL(
              OUTPUT('"No, I am Spartacus" confessed another'),
              Chesney,
              OUTPUT('"Ok, so you are!"')
          );
  </programlisting>

  <para>yields:</para>
  <programlisting>
"I am Spartacus" said one from the mob
"I am the one and only!" said Chesney
"Oh yeah, prove it?"
"No, I am Spartacus" confessed another
"Ok, so you are!"
  </programlisting>

  <para>See Also: <link linkend="SEQUENTIAL">SEQUENTIAL</link></para>

</sect1>