<scope> - Business Process and Data Transformation Language Reference

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InterSystems IRIS Data Platform 2019.2 / Business Process and Data Transformation Language Reference / BPL Elements

Business Process and Data Transformation Language Reference

<scope>

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Define the error handling mechanisms for a sequence of activities.

Synopsis

<scope>   <throw fault='"MyFault"'/>         ...   <faulthandlers>     <catch fault='"MyFault"'>           ...     </catch>   </faulthandlers> </scope>

Details

Attribute or Element	Description
name, disabled, xpos, ypos, xend, yend attributes	See “Common Attributes and Elements.”
<annotation> element	See “Common Attributes and Elements.”
Other elements	Optional. <scope> may contain zero or more of the following elements in any combination: <alert>, <assign>, <branch>, <break>, <call>, <code>, <continue>, <delay>, <empty>, <flow>, <foreach>, <if>, <label>, <milestone>, <reply>, <rule>, <scope>, <sequence>, <sql>, <switch>, <sync>, <throw>, <trace>, <transform>, <until>, <while>, <xpath>, or <xslt>.

Description

To enable error handling, BPL defines an element called <scope>. A scope is a wrapper for a set of activities. This scope may contain one or more activities, one or more fault handlers, and zero or more compensation handlers. The fault handlers and are intended to catch any errors that activities within the <scope> produce. The fault handlers may invoke compensation handlers to compensate for those errors.

The following example provides a <scope> with a <faulthandlers> block that includes a <catchall>:

XData BPL
{
<process language='objectscript'
         request='Test.Scope.Request'
         response='Test.Scope.Response' >
  <sequence>
    <trace value='"before scope"'/>
    <scope>
      <trace value='"before assign"'/>
      <assign property="SomeProperty" value="1/0"/>
      <trace value='"after assign"'/>
      <faulthandlers>
        <catchall>
          <trace value='"in catchall faulthandler"'/>
          <trace value=
            '"%LastError "_
            $System.Status.GetErrorCodes(..%Context.%LastError)_
            " : "_
            $System.Status.GetOneStatusText(..%Context.%LastError)'
            />
        </catchall>
      </faulthandlers>
    </scope>
    <trace value='"after scope"'/>
  </sequence>
</process>
}

When a <scope> provides no <faulthandlers> block, InterSystems IRIS automatically outputs the system error to the Event Log. When a <scope> does contain a <faulthandlers> block, the BPL business process must output <trace> messages to the Event Log for system error messages to appear there. System error messages do appear on the Terminal console, in either case.

It is possible to nest <scope> elements. An error or fault that occurs within the inner scope may be caught within the inner scope, or the inner scope may ignore the error and allow it to be caught by the <faulthandlers> block in the outer scope.

For details, see “BPL Error Handling Conventions” in Developing BPL Processes.