This example pipeline demonstrates how to use the PipeLoop to iteratively execute a child pipeline that increments a numerical value until it reaches the specified threshold.

Broadly, the pipelines perform the following tasks:

• Parent pipeline: The parent pipeline generates the initial input using the JSON Generator Snap. The PipeLoop Snap iteratively calls the child pipeline until the condition specified in the Stop condition is met or the iteration limit is reached.

• Child pipeline: The Mapper Snap in the child pipeline processes the mapping and transformation of data as needed during each iteration.

Parent Pipeline

Child Pipeline

This pipeline increments the $num variable by 1 and adds the passed-in _foo parameter to the output document.

1. Configure the Mapper Snap with the following settings:
   • Define the mappings between the input fields and the desired output fields.
   • Ensure that the output document produced by the Mapper Snap contains the necessary information for the stop condition in the PipeLoop Snap to evaluate.
     
     Final Output: Once the stop condition is met or the iteration limit is reached, the pipeline's final output is collected and passed to the next step or processed further based on the overall workflow.
     Download the pipelines:

     • Parent pipeline: example-pipeloop-snap.slp
     • Child pipeline: child-pipeline.slp

1. If additional Snaps are required for processing, transformation, or routing in the child pipeline, configure those accordingly.
2. Examples might include:

   • Filter Snap to filter out unnecessary data.

   • Data Transformation Snaps for applying complex transformations.

   • HTTP Client or Database Snaps if external calls or data lookups are needed.

3. Return Output to Parent Pipeline:

   • Once the child pipeline completes its steps, it should return its output document to the parent pipeline.

   • This output will be used by the PipeLoop Snap in the parent pipeline to evaluate the stop condition or proceed with further iterations.

4. Execute the PipeLoop Snap. The parent pipeline will pass the generated JSON input to the PipeLoop Snap, which then initiates the iterative process by calling the child pipeline.
5. Evaluate the Output:

   • After each iteration, the PipeLoop Snap evaluates the output document from the child pipeline.

   • The stop condition condition will be assessed to determine if further iterations are necessary or if the loop should end.