Do

Purpose

The Do task is a fundamental control flow construct in the Serverless Workflow DSL. Its primary purpose is to define a sequence of one or more sub-tasks that are executed in the order they are declared.

The output of one task in the sequence becomes the input for the next, facilitating data flow through the defined steps.

Basic Usage

Here’s a simple example of a Do task executing two sub-tasks sequentially:

document:
  dsl: '1.0.0'
  namespace: examples
  name: sequential-tasks
  version: '1.0.0'
do: # This is the main 'Do'
  - step1:
      do: # This is a `Do` task containing sub-tasks
        - taskA:
            set:
              result: "Value from Task A"
        - taskB:
            set:
              # Input to taskB is the output of taskA
              resultB: "${ .result + ' and Task B' }"

# Workflow output will be { "resultB": "Value from Task A and Task B" }

In this example, taskA executes first, setting the result field. Its output is then implicitly passed as input to taskB, which uses that result to compute its own resultB.

Configuration Options

The Do task itself has standard task configuration options like input, output, if, and then. Its main defining characteristic is the do block containing the sequence of sub-tasks.

`do` (List<String: Object>, Required)

This mandatory property contains a list of key-value pairs, where each key is a unique name for the sub-task and the value defines the sub-task to be executed. The sub-tasks are executed sequentially in the order they appear in the list.

Each element in the list specifies a unique name for the sub-task and the task definition itself (e.g., set, call, another do, etc.). The order in the list determines the execution sequence.

do:
  - myDoTask: # Name of the parent Do task
      do: # The 'do' property containing the list of sub-tasks
        - firstSubTask:
            call: http
            with:
              uri: https://api.example.com/data
              method: get
        - secondSubTask:
            set:
              processedData: "${ .body }" # Access output from firstSubTask

Data Flow

This task supports standard configuration for the Data Flow (including input, output, export, and schemas). Refer to those pages for details on these common properties and how they apply generally.

Flow Control

This task supports standard configuration for the Flow Control (including conditional execution with if and branching with then). Refer to those pages for details on these common properties and how they apply generally.

Do