What is the inline mode? - CloudFlow - Alibaba Cloud Documentation Center

By default, Map states run in inline mode. The inline mode can be used to batch-process data and streamline data transformation and processing. The mode focuses on a single node and is suitable for scenarios in which each element in a collection requires processing.

Overview

A Map state is used to traverse a parameter of the array type in the input and execute the Processor states in parallel for all elements in the array. A Map state is similar to the foreach statement in programming languages. However, the iterations in Map are executed in parallel.

When a Map state is executed, the Processor states of all elements in the input parameter are concurrently executed. By default, a map[string]any output that contains the results of all branches is returned after all branches are executed. Then, the system uses the output constructor to further process the results.

The following table describes the fields in the inline mode.

Field	Type	Required	Description	Example
Name	string	Yes	The name of the state.	my-state-name
Description	string	No	The description of the state.	describe it here
Type	string	Yes	The type of the state.	Map
InputConstructor	map[string]any	No	The input constructor.	See Inputs and outputs.
ItemsPath	string	Yes	The expression that is used to extract an array within an input.	See ItemsPath.
Processor	Processor	Yes	The iteration processor.	See Processor.
OutputConstructor	map[string]any	No	The output constructor.	See State OutputConstructor.
Next	string	No	The next state that is executed after the current state is complete. If the value of the End field is true, you do not need to specify this field.	my-next-state
End	bool	No	Specifies whether the state is the terminal state of the current scope.	true
Retry	Retry	No	The error retry policy.	See Error handling.
Catch	Catch	No	The error catch policy.	See Error handling.
MaxConcuccency	int	No	The maximum concurrency level.	28

Important fields for the inline mode

ItemsPath

The expression that is used to extract an array within an input. If a JSON array is returned after an ItemsPath expression is executed, the array is iterated over. Each element in the array is passed to ItemProcessor for processing. You can use the $Context and $Input expression variables, as shown in the following example:

$Input.FieldA

Processor

The iteration processor. The field contains two fields described in the following table.

Field	Type	Required	Description	Example
States	array	Yes	The array of states.	`Processor: StartAt: Pass1 States: - Type: Pass Name: Pass1 End: true`
StartAt	string	Yes	The state from which the execution of the workflow starts.	my start task

MaxConcuccency

The maximum number of concurrent sub-flows. The maximum value of this field is 40.

Sample code

The following sample flow defines a Map state. The MapProcessor contains a Pass state.

Type: StateMachine
Name: my-wkfl
SpecVersion: v1
StartAt: Map1
States:
  - Type: Map
    Name: Map1
    End: true
    InputConstructor:
      FieldA: 
        - a : b
        - c : d
        - e : f
    ItemsPath: $Input.FieldA
    Processor:
      StartAt: Pass1
      States:
        - Type: Pass
          Name: Pass1
          End: true

The following sample code provides an example of the input construction result of the flow.

{
    "FieldA": [
        {
            "a": "b"
        },
        {
            "c": "d"
        },
        {
            "e": "f"
        }
    ]
}

For a Map, the system merges the outputs of all iteration processors. By default, the Items keyword is used as the key and the merged result is used as the value. The following sample code provides an example of the output of Map1. This is also the final output after the flow is executed.

{
    "Items": [
        {
            "a": "b"
        },
        {
            "c": "d"
        },
        {
            "e": "f"
        }
    ]
}