CloudFlow:Integrate CloudFlow with Function Compute

Key concepts

RequestComplete

The flow invokes the function and waits for the API response. After the system responds and returns the result, the flow advances to the next state. This mode works with synchronous invocations, asynchronous invocations, and asynchronous task invocations.

For more information, see RequestComplete.

WaitForSystemCallback

The flow sends the invocation request, then waits for Function Compute to send a system callback notification. The flow advances only after receiving that callback. This mode works with asynchronous invocations and asynchronous task invocations only.

For more information, see WaitForSystemCallback.

WaitForCustomCallback

The flow invokes the function, then pauses. It advances only when your program calls the CloudFlow callback API to report the task result. This mode works with asynchronous invocations and asynchronous task invocations only.

To use this mode, add a callbackToken field to the body parameter and reference the $Context.Current.TaskToken expression. This token is the credential your program must include when reporting the task result back to the flow.

Type: StateMachine
Name: MyWorkflow
SpecVersion: v1
StartAt: invoke-with-callback
States:
  - Name: invoke-with-callback
    Type: Task
    Action: FC:InvokeFunction
    TaskMode: WaitForCustomCallback
    Parameters:
      resourceArn: acs:fc:::services/myService1.LATEST/functions/myFunction1
      invocationType: Async
      body:
        callbackToken.$: $Context.Current.TaskToken
        key1: value1
    End: true

In this example, the flow passes the task token to the function via callbackToken. The function (or a downstream process) calls the ReportTaskSucceeded or ReportTaskFailed API with this token to notify CloudFlow of the result.

For more information, see WaitForCustomCallback.

For details on function invocation types, see Synchronous invocations, Asynchronous invocations, and Asynchronous task management.

RequestComplete mode

The flow wraps the function's return value in a JSON object with a Body field:

{
    "Body": "function invocation result"
}

Access the return value with $Output.Body in subsequent state definitions. If the return value is a JSON object, deserialize it with the workflow's built-in function, then access its members as a standard JSON object.

The following example invokes a function, then uses a Choice state to branch based on a value from the function's output:

Type: StateMachine
Name: MyWorkflow
SpecVersion: v1
Description: ' '
StartAt: Example 1 of function invocation
States:
  - Name: Example 1 of function invocation
    Type: Task
    TaskMode: RequestComplete
    Action: FC:InvokeFunction
    Parameters:
      resourceArn: acs:fc:::services/myService1.LATEST/functions/myFunction1
      invocationType: Sync
      body:
        argument1.$: $Input.Records
        argument2.$: $Input.BucketName
    Next: conditional statement
  - Type: Choice
    Name: conditional statement
    Branches:
      - Condition: $Input.ObjectSize >= $Input.Threshold
        Next: Example 2 of function invocation
    Default: No action is performed.
  - Type: Pass
    Name: No action is performed.
    End: true
  - Name: Example 2 of function invocation
    Type: Task
    TaskMode: RequestComplete
    Action: FC:InvokeFunction
    Parameters:
      resourceArn: acs:fc:::services/myService2.LATEST/functions/myFunction2
      invocationType: Sync
      body:
        argument1.$: $Input.BucketName
        argument2.$: $Input.TaskId
    End: true

WaitForSystemCallback and WaitForCustomCallback modes

In these modes, the external system calls the ReportTaskSucceeded or ReportTaskFailed API to report the result. The flow passes the result through without wrapping it. For example, if the function returns {"message": "hello"}, the result in the flow is:

{
    "message": "hello"
}

Access the return value directly with the $Output expression.