Workflow Executor
Usage
By default, the specified workflow will be executed once for each input row (this can be changed in the Row Grouping tab).
Fields from the data row(s) can be used to set parameters and variables and it is passed to the workflow in the form of a result row. Remember that all parameters must be defined at least once in each pipeline or workflow (Edit pipeline/workflow properties). You are passing a parameter when you send a field/parameter/variable to a workflow executor from the Parameters tab.
You can also allow a group of records to be passed based on the value in a field (when the value changes the workflow is executed) or on time. In these cases, the first row of the group or rows is used to set parameters or variables in the workflow.
It is possible to launch multiple copies of this transform to facilitate parallel workflow processing.
See also:
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The Workflow action that executes a sub-workflow from a workflow.
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The Pipeline action that executes a pipeline from a workflow.
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The Pipeline Executor transform that executes a sub-pipeline from a pipeline.
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The Loops in Apache Hop how-to guide.
Samples (samples project)
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loops/workflow-executor.hpl
Options
General
| Option | Description |
|---|---|
Transform name | Name of the transform. |
Workflow | Use this option to specify a workflow stored in a file (.hwf file) |
Parameters Tab
In this tab you can specify which field to use to set a certain parameter or variable value. If you specify an input field to use, the static input value is not used. If multiple rows are passed to the workflow, the first row is taken to set the parameters or variables.
There is a button in the lower right corner of the tab that will insert all the defined parameters of the specified workflow. For information the description of the parameter is inserted into the static input value field.
| If you leave the "Inherit all variables from pipeline" option checked (it is by default), all the variables defined in the current pipeline are passed to child workflow. |
The Get Parameters button in the lower right corner of the tab that will insert all the defined parameters with their description for the specified workflow
The Map Parameters button in the lower right corner of the tab lets you map fields in the current pipeline to parameters in the child workflow.
Row Grouping Tab
On this tab you can specify the amount of input rows that are passed to the workflow in the form of result rows. You can use the result rows in a workflow or Pipeline workflow action to loop over or you can get the records themselves in a Get rows from result transform in a pipeline.
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The number of rows to send to the workflow: after every X rows the workflow will be executed and these X rows will be passed to the workflow.
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Field to group rows on: Rows will be accumulated in a group as long as the field value stays the same. If the value changes the workflow will be executed and the accumulated rows will be passed to the workflow.
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The time to wait collecting rows before execution: This is time the transform will spend accumulating rows prior to the execution of the workflow.
Please note that you can only specify one method of grouping.
Execution Results Tab
You can specify result fields and to which transform to send them. If you don’t need a certain result simply leave a blank input field.
Result Rows Tab
In the "Result rows" tab you can specify the layout of the expected result rows of this workflow and to which transform to send them after execution.
The workflow executor performs a consistency check over the fields we declared in this tab as the fields that want to receive in output. The check will be performed by making sure the fields we require are really present in the results stream and that type of each fields is really the type we expected to be. If there are any differences an error will be thrown. The error will give you the complete picture about which fields are missing and/or which fields were declared by considering a wrong datatype.
Note: remember that currently this transform always give you a result row back even if the pipelines started in the sub-workflow don’t return any result. In this case, the result row that you will get back will contain only the fields provided by the flow as input of this transform.