Overview

You can use this Snap to enable looping on pipeline executions based on a stop condition or iteration limit. The output document of each iteration is fed into the next iteration as the input document and continues execution until the stop condition is met or the iteration limit is reached.

Snap Type

The PipeLoop Snap is a Flow-type Snap.

Prerequisites

Child pipelines must have one input view and one output view.

Support for Ultra Pipelines

Does not work in Ultra Pipelines.

Limitations

Reuse is currently not supported because of the requirement to close an input view to force flush all documents out.
Reads only the first output document for a specific input document (the remaining documents are ignored and dropped).
Supports expressions on the pipeline specification, but only evaluates the input document to PipeLoop, not for each iteration.

Known Issues

None.

Snap Views

Type

Format

Number of Views

Examples of Upstream and Downstream Snaps

Description

Input

Binary
Document

Min: 1
Max: 1

Mapper
Copy

The document or binary data to send to the child pipeline. For a single document input, only the first output document is captured in the output document and the remaining documents are ignored.

Output

Binary
Document

Min: 1
Max: 1

Mapper

If you select the Debug iterations output checkbox, an additional _iteration_documents is added to the output document alongside the output documents and passthrough documents.

_iteration_documents contains the following fields:

iteration: The index of the loop iteration.
child_pipeline_output: The output document of the respective iteration.
stop_condition_evaluation: The evaluated result of the stop condition.

Error

Error handling is a generic way to handle errors without losing data or failing the Snap execution. You can handle the errors that the Snap might encounter when running the pipeline by choosing one of the following options from the When errors occur list under the Views tab:

Stop Pipeline Execution: Stops the current pipeline execution if the Snap encounters an error.
Discard Error Data and Continue: Ignores the error, discards that record, and continues with the remaining records.
Route Error Data to Error View: Routes the error data to an error view without stopping the Snap execution.

Learn more about Error handling in pipelines.

Snap Settings

Expression : JavaScript syntax to access SnapLogic Expressions to set field values dynamically (if enabled). If disabled, you can provide a static value. Learn more.
SnapGPT : Generates SnapLogic Expressions based on natural language using SnapGPT. Learn more.
Suggestion : Populates a list of values dynamically based on your Account configuration.
Upload : Uploads files. Learn more.

Learn more about the icons in the Snap Settings dialog.

Field Name		Field Type	Description
Label* Default Value: PipeLoop Example: SimpleLoop		String	Specify the name for the Snap. You can modify this to be more specific, especially if you have more than one of the same Snaps in your pipeline.
Pipeline* Default Value: N/A Example: demo-child-pipeline		String/Expression	Specify the path of the pipeline to execute.
Pipeline Parameters	Use this field set to define child pipeline parameters to use for executing the pipeline.
	Parameter name Default Value: N/A Example: tools	String/Suggestion	Specify the parameter's name. You can also select the Pipeline Parameters defined for the pipeline selected in the Pipeline field.
	Parameter value Default Value: N/A Example: $tools	String/Expression	Specify the value for the pipeline parameter, which can be an expression based on incoming documents or a constant. If you configure the value as an expression based on the input, then each incoming document or binary data is evaluated against that expression when invoking the pipeline. The result of the expression is JSON-encoded if it is not a string. The child pipeline then needs to use the `JSON.parse()` expression to decode the parameter value.
Loop options		Define the iteration configuration.
Stop condition Default Value: N/A Example: `$num >= 10`		String/Expression	Specify the condition to be evaluated during execution that decides whether the execution should stop or continue. The iteration continues until the stop condition is met or the iteration limit is reached. The Snap errors out if the Stop condition cannot be evaluated at run time. The stop condition is evaluated on the output document from each iteration.
Iteration limit Default Value: 10 Example: 15		Integer/Expression	Specify the maximum limit for the number of iterations to run to avoid infinite loops.
Debug iteration outputs Default Value: Deselected		Checkbox	Select this checkbox to include the index, output document, and stop condition evaluation for each iteration as part of the output format.
Execution options		Define the child pipeline execution configuration.
Execute on Default Value: LOCAL_NODE Example: LOCAL_SNAPLEX		Dropdown list	Select one of the following Snaplex options to specify the target Snaplex for the child pipeline: LOCAL_NODE: Runs the child pipeline on the same node as the parent pipeline. LOCAL_SNAPLEX: Runs the child pipeline on one of the available nodes in the same Snaplex as the parent pipeline.
Execution label Default Value: N/A Example: demo		String/Expression	Specify the label to display in the Dashboard for the current execution.
Snap Execution Default Value: Validate & Execute Example: Execute only		Dropdown list	Select one of the following three modes in which the Snap executes: Validate & Execute: Performs limited execution of the Snap and generates a data preview during pipeline validation. Subsequently, performs full execution of the Snap (unlimited records) during pipeline runtime. Execute only: Performs full execution of the Snap during pipeline execution without generating preview data. Disabled: Disables the Snap and all Snaps that are downstream from it.

Example

Snap Pack History

Click to view/expand

Release	Snap Pack Version	Date	Type	Updates
November 2024	main29029	13 Nov 2024	Stable	Updated and certified against the current SnapLogic Platform release.
August 2024	438patches28470	22 Oct 2024	Latest	Added the PipeLoop Snap that enables you to loop on pipeline executions based on a stop condition or iteration limit. The execution workflow of this Snap enables the parent pipeline to control and manage iterative processes using the child pipeline, for scenarios where repeated processing is needed until a specific stop condition is met.
August 2024	438patches28047	16 Sep 2024	Latest	Enhanced the Head and Tail Snaps (for the Number of documents and Document offset fields) to support pipeline parameters via expressions that enable you to reuse the pipelines.
August 2024	main27765	21 Aug 2024	Stable	When the Router Snap was the first Snap in a triggered task, the documents were not processed. Previously, the response contained a `200 status code` but was empty. Now, it processes one document and provides non-empty output. Behavior change: Previously, the Router Snap generated no output without an input document. Now, the Snap generates an empty document when no input document is provided.
May 2024	437patches26857	10 Jul 2024	Latest	Enhanced the Pipeline Execute Snap to support expression values via pipeline parameters for the Batch size field that enables you to use intermediate pipelines for generic use cases.
May 2024	main26341	08 May 2024	Stable	Updated and certified against the current SnapLogic Platform release.
March 2024	436patches25576	19 Mar 2024	Latest	Fixed an issue with the Pipeline Execute Snap where a condition resulted in the output documents not being read.
February 2024	main25112	14 Feb 2024	Stable	Updated and certified against the current SnapLogic Platform release.
November 2023	main23721	08 Nov 2023	Stable	Updated and certified against the current SnapLogic Platform release.
August 2023	434patches22576	23 Aug 2023	Latest	Fixed an issue with the Pipeline Execute Snap that caused a null pointer exception during the retry when the input view was a Binary type. Retry is not supported for a Binary input view with this Snap.
August 2023	main22460	16 Aug 2023	Stable	Updated and certified against the current SnapLogic Platform release.
May 2023	433patches22107	08 Aug 2023	Latest	Fixed an issue with the Pipeline Execute Snap that caused it to acknowledge the Ultra pipeline message before the message reached the last Snap in the pipeline. Because of the early acknowledgment, the last Snap in the pipeline failed and the response could not be sent back.
May 2023	433patches21744	28 Jun 2023	Latest	Fixed an issue with the Pipeline Execute Snap where a missing label produced a null pointer exception.
May 2023	433patches21196	25 May 2023	Latest	Fixed an issue with the Pipeline Execute Snap where no input view produced a null pointer exception.
May 2023	433patches21040	15 May 2023	Latest	Provided a fix to ensure the Data Validator works with "unknown" data types.
May 2023	main21015	10 May 2023	Stable	Upgraded with the latest SnapLogic Platform release.
February 2023	432patches20279	29 Mar 2023	Latest	The Pipeline Execute Snap now returns errors from child pipelines with a unique identifier.
February 2023	432patches19695	07 Mar 2023	Latest	Fixed an issue with the Pipeline Execute Snap that was causing `Unable to create a deep copy of the object` errors. As of 29 Mar 2023 we have discovered an issue with this patch affecting the Pipeline Execute Snap. If you have pipelines leveraging the Pipeline Execute Snap, we recommend you NOT use this patch and instead use patch 432patches20279.
February 2023	main19844	09 Feb 2023	Stable	Upgraded with the latest SnapLogic Platform release.
November 2022	main18944	10 Nov 2022	Stable	Upgraded with the latest SnapLogic Platform release.
September 2022	430patches18070	22 Sep 2022	Latest	The Pipeline Execute Snap with binary output that is used in a low-latency feed Ultra Pipeline now works as expected. The requests are now acknowledged correctly.
August 2022	main17386	11 Aug 2022	Stable	Upgraded with the latest SnapLogic Platform release.
4.29	main15993	14 May 2022	Stable	Upgraded with the latest SnapLogic Platform release.
4.28 Patch	428patches15026	22 Mar 2022	Latest	Fixed an issue with HTTP Router Snap where the Snap did not work as intended for a GET request that used a Cloud URL when the HTTP Router was the first Snap in the triggered task Pipeline.
4.28	main14627	12 Feb 2022	Stable	Enhanced the Filter Snap with the Null-safe access checkbox. Select this checkbox to consider the valid values in the filter expression and remove the missing or empty data instead of treating them as null.
4.27 Patch	427patches13726	18 Jan 2022	Latest	Enhanced the Filter Snap with the Null-safe access checkbox. Select this checkbox to consider the missing data or empty value as null when accessing the source path.
4.27	main12833	13 Nov 2021	Stable	Enhanced the Gate Snap with the Output Document Content field that enables you to indicate the count of input documents and the specific (first or last) document to include in the output.
4.26	main11181	14 Aug 2021	Stable	Added Binary Copy Snap to copy a binary stream to the Snap’s output views. You can use this Snap if you want to send the same information to multiple endpoints.
4.25 Patch	425patches10571	08 Sep 2021	Latest	Enhanced the performance of Binary Router Snap via more efficient IO utilization.
4.25	main9554	08 May 2021	Stable	Enhanced the HTTP Router Snap to support Ultra Pipelines.
4.24	main8556	13 Feb 2021	Stable	Added the Ignore empty stream checkbox to the Gate Snap Settings
4.23	main7430	14 Nov 2020	Stable	Enhances the Data Validator Snap by making the Constraint value field as optional under the Constraints.
4.22	main6403	12 Sep 2020	Stable	Upgraded with the latest SnapLogic Platform release.
4.21 Patch	flow8855	-	Latest	Fixes the Binary Router Snap's failure in Ultra Pipelines by preventing a deep-copy (performing a copy of the original objects recursively) of binary data headers.
4.21	snapsmrc542	-	Stable	Upgraded with the latest SnapLogic Platform release.
4.20	snapsmrc535	-	Latest	Adds a new Snap, Gate, which enables you to consolidate multiple input streams into a single output document where each input stream is displayed as a label containing the list of records that were received by that input view. The Pipeline Execute Snap now provides the following capabilities: Specify the Snaplex on which to run child Pipelines. You can now select the Snaplex on which to run the child Pipelines through the Execute On and Snaplex Path fields. The default option is executing the child Pipeline on the same Snaplex node as the Parent, but you can also specify a different Snaplex through the drop-down list, which includes the option to manually enter a Snaplex name. Configure retry logic for child Pipeline executions. You can now configure retry logic for child Pipeline executions though the following fields: Number of Retries, Retry Interval, and Timeout fields.
4.19	snaprsmrc528	-	Stable	Upgraded with the latest SnapLogic Platform release.
4.18 Patch	flow7743	-	Latest	Added a property Validate full JSON path to the Data Validator Snap to fix an issue wherein a field validation failure against a constraint does not produce an error.
4.18	snapsmrc523	-	Stable	Upgraded with the latest SnapLogic Platform release.
4.17 Patch	flow7637	-	Latest	Fixed an issue with the Data Validator Snap wherein the output fails to report all but one of the violations when there are multiple constraints of the Required type.
4.17 Patch	ALL7402	-	Latest	Pushed automatic rebuild of the latest version of each Snap Pack to SnapLogic UAT and Elastic servers.
4.17	snapsmrc515	-	Latest	Added the Snap Execution field to all Standard-mode Snaps. In some Snaps, this field replaces the existing Execute during preview check box.
4.16	snapsmrc508	-	Latest	Pipeline Execute Snap: Added the capability to select either document (previously supported) or binary data (new) for your input and output Views.
4.15 Patch	flow6263	-	Latest	Improved the error messages to include the source path of the constraint for data validation failures.
4.15	snapsmrc500	-	Stable	Upgraded with the latest SnapLogic Platform release.
4.14	snapsmrc490	-	Stable	Upgraded with the latest SnapLogic Platform release.
4.13	snapsmrc486	-	Stable	Upgraded with the latest SnapLogic Platform release.
4.12 Patch	flow4895	-	Latest	Fixed an issue in the Data Validator Snap that made multiple copies of lineage on the error path.
4.12	snapsmrc480	-	Stable	Resolved an issue with the Union Snap that caused excessive CPU utilization.
4.11 Patch	flow4461	-	Latest	Fixed an issue with the Pipeline Execute Snap that could cause the parent pipeline to freeze when the child pipeline fails.
4.11 Patch	flow4292	-	Latest	Resolved an issue with the Union Snap in Ultra Mode that spikes the CPU utilization to ~30% during startup of 120 instances.
4.11	snapsmrc465	-	Stable	Upgraded with the latest SnapLogic Platform release.
4.10	snapsmrc414	-	Stable	Upgraded with the latest SnapLogic Platform release.
4.9.0 Patch	flow3094	-	Latest	Addressed an issue in Binary Router where the Snap did not wait until all threads were completed to write data to the output views.
4.9.0 Patch	flow3320	-	Latest	Data Validator Snap - fixed Type constraint feature.
4.9	snapsmrc405	-	Stable	Upgraded with the latest SnapLogic Platform release.
4.8.0	snapsmrc398		Stable	Filter: Snap-aware error handling policy enabled for Spark mode. This ensures the error handling specified on the Snap is used.
4.7.0 Patch	flow2598		Latest	Addressed a possible race condition when reusing pipelines with a Pipeline Execute Snap.
4.7.0	flow2297		Stable	Fixed an issue with Ultra pipeline when invoking, using Pipeline Execute, a child pipeline that contains a non-Ultra compatible Snap.
4.7.0	snapsmrc382		Stable	Recommendation: The Pipeline Execute Snap is meant to eventually replace ForEach and Task Execute. It is suggested you use Pipeline Execute for all new pipelines and update existing pipelines at your earliest convenience. Updated the Pipeline Execute Snap with Execute during preview field.
4.6.0 Patch	flow1909		Latest	Resolved an issue with Union Snap slowing down pipelines.
4.6.0	snapsmrc362		Stable	The following Snaps now support error view in Spark mode: Copy, Union. ForEach: The value for the Maximum instances property is limited to a maximum of 100. A value higher than 100 will automatically be limited down to 100 during pipeline execution. Pipeline Execute: Snaplex property added to let you specify the Snaplex on which to run the child pipeline. Resolved an issue in Task Execute Snap that caused an internal server error (status code: 500). Resolved an issue in Pipeline Execute Snap that did not show parameter suggestions when the pipeline is selected from another project. Resolved an issue in Copy Snap that showed errors on the UI while the Javascript was being executed. Resolved an issue in Filter Snap that failed with "could not filter the document" if upstream data for ServiceNow Query.
4.5.1	flow1574		Latest	Resolved an issue with Pipeline Execute not able to load pipeline selected from the pipeline picker property. Enhanced error handling in Pipeline Execute for when Reuse is enabled and the pipeline path is an expression whose result is not constant. Resolved an issue in Pipeline Execute not including the runtime ID and state in error documents.
4.5.0	snapsmrc344		Stable	NEW! Pipeline Execute introduced in this release. This Snap provides a way to flexibly and efficiently execute pipelines and flowing documents into and out of these executions. Resolved an issue in Task Execute Snap to ensure JAVA 7 and JAVA 8 Snaplex give the same output. Resolved an issue with the Router Snap routing to the wrong output when used in Spark mode
4.4.0			Stable	Resolved an issue with Exit Snap hanging during validation if threshold is not met. Spark support added to the Copy, Filter, Router, and Union Snaps.
4.3.2			Latest	Resolved an issue with Task Execute where java.math.BigInteger cannot be cast to java.lang.String exception if input document variable was a numeric type. Resolved an issue with Task Execute failing with expression enabled. Resolved an issue with data preview not working in the ForEach Snap. Resolved an issue with Execute during Preview functionality broken in the ForEach Snap. Resolved an issue with ForEach Snap not representing the output schema correctly during preview.
4.3.1			Latest	Resolved an issue with the ForEach poll interval being inconsistent.
4.3.0			Stable	In Data Validator, the pattern option now works with partial matches. Exit Snap Error handling improved to handle messages that are non-strings. Exit Snap now supports expressions in the Exit error message property. ForEach Snap now generates output documents when run. Output documents will also be produced if a child pipeline called by the ForEach is manually stopped.
4.2.2			Latest	Resolved an issue in ForEach where a recursive pipeline in synchronous mode was unable to finish execution. Resolved an issue in Data Validator not working for partial matches.
		August 7, 2015 (2015.25/4.2.1)		NEW! Exit Snap introduced in this release. This Snap forces a pipeline to stop with a failed status if it receives more records than the user-defined threshold. Resolved error in ForEach Snap where an exposed error view triggered a pipeline failure.
		June 27, 2015 (2015.22)		The Router Snap now supports even distribution across all output views if no expressions are defined. With this change, Routes is no longer a required field.
		June 6, 2015 (2015.20)		Task Execute should have Execute on preview Directory Browser Snap did not render output data when running from "Windows" Groundplex.
		May 15, 2015		ForEach: Error was not thrown on validation if the child pipeline was not provided.
		May 2, 2015		Binary Router: enhanced error handling Filter: bug fixes Router: bug fixes
		December 20, 2014		Updated Snaps may include new or changed functionality or be otherwise improved. Data Validator: Type constraint added. Union Snap: Preserve order was removed.
		July/Summer 2014		NEW! Binary Router Snap introduced in this release. NEW! Task Execute Snap introduced in this release.
		June 30, 2014		Data Validator (Beta Release). This Snap validates incoming documents and their attributes against constraints you define. ForEach: Addressed an issue with parallel execution not working properly.
		April 2014		ForEach Snap updated to support Snaplex selection and pipeline parameters.
		January 2014		NEW! ForEach Snap introduced in this release.
		November 2013		NEW! Head Snap introduced in this release. NEW! Tail Snap introduced in this release.
		Initial Release (June 2013)		Router Snap introduced in this release. Copy Snap introduced in this release. Union Snap introduced in this release. Filter Snap introduced in this release.

Related links:

https://docs.snaplogic.com/snaps/snaps-machine-learning/snaps-machine-learning-about.html