Parallel State

The Parallel class allows concurrent processing, across arbitrary numbers of branches.

For more details on Parallel, see the AWS documentation.

class awssl.Parallel(Name=None, Comment='', InputPath='$', OutputPath='$', NextState=None, EndState=None, ResultPath='$', RetryList=None, CatcherList=None, BranchList=None)

Models the Parallel state.

Either:

  • EndState is True and NextState must be None
  • EndState is False and NextState must be a valid instance of a class derived from StateBase.

Output is returned as a list of the outputs from each branch.

Parameters:
  • Name (str) – [Required] The name of the state within the branch of the state machine
  • Comment (str) – [Optional] A comment describing the intent of this pass state
  • InputPath (str) – [Optional] Filter on the Input information to be passed to the Pass state. Default is “$”, signifying that all the Input information will be provided
  • OutputPath (str) – [Optional] Filter on the Output information to be returned from the Pass state. Default is “$”, signifying that all the result information will be provided
  • EndState (bool) – [Optional] Flag indicating if this state terminates a branch of the state machine. Defaults to False
  • NextState (instance of class derived from StateBase) – [Optional] Next state to be invoked within this branch. Must not be None unless EndState is True
  • ResultPath (str) – [Optional] JSONPath indicating where results should be added to the Input. Defaults to “$”, indicating results replace the Input entirely.
  • RetryList – [Optional] list of Retrier instances corresponding to error states that cause the entire set of branches to be retried
  • CatcherList – [Optional] list of Catcher instances corresponding to error states that can be caught and handled by further states being executed in the StateMachine.
  • BranchList – [Required] list of StateBase instances, providing the starting states for each branch to be run concurrently
Type:

RetryList: list of Retrier
Type:

CatcherList: list of Catcher
Type:

BranchList: list of StateBase
add_branch(StartObject=None)

Adds a branch starting at the specified StartObject, which must be inherited from StateBase.

clone(NameFormatString='{}')

Returns a clone of this instance, with the clone named per the NameFormatString, to avoid state name clashes.

If this instance is not an end state, then the next state will also be cloned, to establish a complete clone of the branch form this instance onwards.

Parameters:NameFormatString (str) – [Required] The naming template to be applied to generate the name of the new instance.
Returns:Parallel – A new instance of this instance and any other instances in its branch.
set_branch_list(BranchList=None)

Sets the list of starting states for each branch to be executed concurrently.

At least one branch is required for the state to be valid.

Parameters:BranchList – [Required] list of StateBase instances, providing the starting states for each branch to be run concurrently
Type:BranchList: list of StateBase
to_json()

Returns the JSON representation of this instance.

Returns:dict – The JSON representation
validate()

Validates this instance is correctly specified.

Raises Exception with details of the error, if the state is incorrectly defined.