Start Workflow

The Start Workflow task starts another workflow from the current workflow. Unlike the Sub Workflow task, the workflow triggered by the Start Workflow task will execute asynchronously. That means the current workflow proceeds to its next task without waiting for the started workflow to complete.

A Start Workflow task is considered successful when the requested workflow enters the RUNNING state, regardless of its final status.

Task parameters

Configure these parameters for the Start Workflow task.

Parameter	Description	Required/ Optional
inputParameters. startWorkflow	A map that includes the requested workflow’s configuration, such as the name and version.	Required.
inputParameters. startWorkflow. name	The name of the workflow to be executed. This workflow should have a pre-existing definition in Conductor.	Required.
inputParameters. startWorkflow. version	The version of the workflow to be executed. If unspecified, the latest version will be used.	Optional.
inputParameters. startWorkflow. correlationId	A unique identifier for the workflow execution, used to correlate the current workflow instance with other workflows.	Optional.
inputParameters. startWorkflow. idempotencyKey	A unique, user-generated key to prevent duplicate workflow executions. Idempotency data is retained for the life of the workflow execution.	Optional.
inputParameters. startWorkflow. idempotencyStrategy	The idempotency strategy for handling duplicate requests. Supported values: RETURN_EXISTING—Return the workflowId of the workflow instance with the same idempotency key. FAIL—Start a new workflow instance only if there are no workflow executions with the same idempotency key. FAIL_ON_RUNNING—Start a new workflow instance only if there are no RUNNING or PAUSED workflows with the same idempotency key. Completed workflows can run again.	Required if idempotencyKey is used.

In addition, you can also configure the requested workflow’s input in inputParameters.startWorkflow.input, which will be passed to the invoked workflow.

Other generic parameters

Here are other parameters for configuring the task behavior.

Parameter	Description	Required/ Optional
optional	Whether the task is optional. The default is false. If set to true, the workflow continues to the next task even if this task is in progress or fails.	Optional.

Task configuration

This is the task configuration for a Start Workflow task.​

{
  "name": "start_workflow",
  "taskReferenceName": "start_workflow_ref",
  "inputParameters": {
    "startWorkflow": {
      "name": "someName",
      "input": {
        "someParameter": "someValue",
        "anotherParameter": "anotherValue"
      },
      "version": "",
      "idempotencyKey": "",
      "idempotencyStrategy": "RETURN_EXISTING",
      "correlationId":
    }
  },
  "type": "START_WORKFLOW"
}

Task output

The Start Workflow task will return the following parameters.

Parameter	Description
workflowId	The workflow (execution) ID of the started workflow execution.

note

The Start Workflow task will not return the output of the started workflow.

Adding a Start Workflow task in UI

To add a Start Workflow task:

1. In your workflow, select the (+) icon and add a Start Workflow task.
2. Enter the Workflow name and Version. If the version is unspecified, the latest version will be used. Once selected, the workflow’s input parameters will automatically appear if there are any pre-defined ones.
3. (Optional) Enter the Correlation id.
4. (Optional) Enter the Idempotency key and select the Idempotency strategy.
5. (Optional) Add any additional input parameters for the workflow.

Examples

Here are some examples for using the Start Workflow task.

Using the Start Workflow task in a workflow

To demonstrate the Start Workflow task, consider the following sample workflow. This example shows how to configure a workflow that starts another workflow.

{
  "name": "sample_start_workflow",
  "description": "Sample Workflow to start a new workflow.",
  "tasks": [
    {
      "name": "start",
      "taskReferenceName": "start_ref",
      "inputParameters": {
        "startWorkflow": {
          "name": "your_workflow_name_to_be_started",
          "version": 3,
          "input": {}
        }
      },
      "type": "START_WORKFLOW"
    }
  ]
}

In the Start Workflow task, the input parameters are defined as:

"inputParameters": {
  "startWorkflow": {
    "name": "your_workflow_name_to_be_started",
    "version": 3
  }
},

This will start a workflow named “your_workflow_name_to_be_started”, with version 3.

The output shows the generated workflow (execution) ID of the started workflow.

// task output

{
  "workflowId": "8ca4184e-6a52-11ed-aaf5-f62716e2ae41"
}

To find the newly started workflow execution, go to Executions > Workflow and search for the workflow containing the Start Workflow task. Select the workflow to view the execution and select the Start Workflow task. The task details Summary tab contains newly-started workflow (execution) ID.

Even if the started workflow is not completed, the main workflow will run to completion.