Exits and Global Forwards

This page covers advanced pipeline flow control: defining exits, using global forwards to reduce repetition, and structuring pipelines for clarity.

Pipeline Exits

Every pipeline must declare at least one <Exit>. Exits define the possible end states of a pipeline and map to HTTP response codes (for API-based adapters).

<Pipeline>
  <Exits>
    <Exit name="Exit" state="SUCCESS" code="200"/>
    <Exit name="Created" state="SUCCESS" code="201"/>
    <Exit name="BadRequest" state="ERROR" code="400"/>
    <Exit name="NotFound" state="ERROR" code="404"/>
    <Exit name="ServerError" state="ERROR" code="500"/>
  </Exits>
  <!-- pipes here -->
</Pipeline>

Exit Attributes

Attribute	Description
name	Unique identifier; referenced by forwards in pipes
state	SUCCESS or ERROR; determines whether the result is treated as successful
code	HTTP status code returned to the caller (for HTTP-based listeners)

A pipe routes to an exit by specifying the exit's name in a <Forward> element's path attribute.

Global Forwards

When multiple pipes need to forward to the same exit or pipe (e.g., a shared error handler), declaring the same <Forward> on every pipe is repetitive. Global forwards solve this by defining forwards at the pipeline level that apply to all pipes.

<Pipeline>
  <Exits>
    <Exit name="Exit" state="SUCCESS" code="200"/>
    <Exit name="BadRequest" state="ERROR" code="400"/>
    <Exit name="ServerError" state="ERROR" code="500"/>
  </Exits>

  <GlobalForward name="exception" path="ServerError"/>
  <GlobalForward name="failure" path="BadRequest"/>

  <XmlValidatorPipe name="validate" root="order" schema="order.xsd">
    <Forward name="success" path="process"/>
    <!-- "failure" forward is inherited from the global forward -->
  </XmlValidatorPipe>

  <SenderPipe name="process">
    <FixedQuerySender query="INSERT INTO orders VALUES(?{id})" datasourceName="jdbc/${instance.name.lc}">
      <Param name="id" xpathExpression="/order/@id"/>
    </FixedQuerySender>
    <Forward name="success" path="Exit"/>
    <!-- "exception" forward is inherited from the global forward -->
  </SenderPipe>
</Pipeline>

How Global Forwards Work

• A global forward applies to all pipes in the pipeline.
• If a pipe declares its own <Forward> with the same name, the pipe-level forward takes precedence (overrides the global).
• Global forwards are typically used for failure and exception outcomes that should route to the same exit across all pipes.

Common Global Forward Names

Forward Name	Typical Use
success	Default success path (rarely used globally)
failure	Validation or processing failures
exception	Unexpected errors or exceptions
parserError	XML parsing errors

Combining Exits and Global Forwards

A well-structured pipeline uses exits to define all possible outcomes and global forwards to establish default routing, with pipe-level forwards only where behavior differs from the default:

<Pipeline firstPipe="validate">
  <Exits>
    <Exit name="Exit" state="SUCCESS" code="200"/>
    <Exit name="BadRequest" state="ERROR" code="400"/>
    <Exit name="ServerError" state="ERROR" code="500"/>
  </Exits>

  <GlobalForward name="failure" path="BadRequest"/>
  <GlobalForward name="exception" path="ServerError"/>

  <XmlValidatorPipe name="validate" root="request" schema="request.xsd">
    <Forward name="success" path="transform"/>
  </XmlValidatorPipe>

  <XsltPipe name="transform" styleSheetName="transform.xsl">
    <Forward name="success" path="store"/>
  </XsltPipe>

  <SenderPipe name="store">
    <FixedQuerySender query="INSERT INTO data VALUES(?{value})">
      <Param name="value" xpathExpression="/result/value"/>
    </FixedQuerySender>
    <Forward name="success" path="Exit"/>
  </SenderPipe>
</Pipeline>

This pattern keeps configurations concise and ensures consistent error handling across all pipes.