Parallel

class aws_cdk.aws_stepfunctions.Parallel(scope, id, *, arguments=None, result_path=None, result_selector=None, comment=None, query_language=None, state_name=None, assign=None, input_path=None, output_path=None, outputs=None)

Bases: State

Define a Parallel state in the state machine.

A Parallel state can be used to run one or more state machines at the same time.

The Result of a Parallel state is an array of the results of its substatemachines.

ExampleMetadata:

nofixture infused

Example:

from aws_cdk import Stack
from constructs import Construct
import aws_cdk.aws_stepfunctions as sfn

class MyJob(sfn.StateMachineFragment):

    def __init__(self, parent, id, *, jobFlavor):
        super().__init__(parent, id)

        choice = sfn.Choice(self, "Choice").when(sfn.Condition.string_equals("$.branch", "left"), sfn.Pass(self, "Left Branch")).when(sfn.Condition.string_equals("$.branch", "right"), sfn.Pass(self, "Right Branch"))

        # ...

        self.start_state = choice
        self.end_states = choice.afterwards().end_states

class MyStack(Stack):
    def __init__(self, scope, id):
        super().__init__(scope, id)
        # Do 3 different variants of MyJob in parallel
        parallel = sfn.Parallel(self, "All jobs").branch(MyJob(self, "Quick", job_flavor="quick").prefix_states()).branch(MyJob(self, "Medium", job_flavor="medium").prefix_states()).branch(MyJob(self, "Slow", job_flavor="slow").prefix_states())

        sfn.StateMachine(self, "MyStateMachine",
            definition_body=sfn.DefinitionBody.from_chainable(parallel)
        )
Parameters:

  • scope (Construct) –

  • id (str) – Descriptive identifier for this chainable.

  • arguments (Optional[Mapping[str, Any]]) – Parameters pass a collection of key-value pairs, either static values or JSONata expressions that select from the input. Default: No arguments

  • result_path (Optional[str]) – JSONPath expression to indicate where to inject the state’s output. May also be the special value JsonPath.DISCARD, which will cause the state’s input to become its output. Default: $

  • result_selector (Optional[Mapping[str, Any]]) – The JSON that will replace the state’s raw result and become the effective result before ResultPath is applied. You can use ResultSelector to create a payload with values that are static or selected from the state’s raw result. Default: - None

  • comment (Optional[str]) – A comment describing this state. Default: No comment

  • query_language (Optional[QueryLanguage]) – The name of the query language used by the state. If the state does not contain a queryLanguage field, then it will use the query language specified in the top-level queryLanguage field. Default: - JSONPath

  • state_name (Optional[str]) – Optional name for this state. Default: - The construct ID will be used as state name

  • assign (Optional[Mapping[str, Any]]) – Workflow variables to store in this step. Using workflow variables, you can store data in a step and retrieve that data in future steps. Default: - Not assign variables

  • input_path (Optional[str]) – JSONPath expression to select part of the state to be the input to this state. May also be the special value JsonPath.DISCARD, which will cause the effective input to be the empty object {}. Default: $

  • output_path (Optional[str]) – JSONPath expression to select part of the state to be the output to this state. May also be the special value JsonPath.DISCARD, which will cause the effective output to be the empty object {}. Default: $

  • outputs (Any) – Used to specify and transform output from the state. When specified, the value overrides the state output default. The output field accepts any JSON value (object, array, string, number, boolean, null). Any string value, including those inside objects or arrays, will be evaluated as JSONata if surrounded by {% %} characters. Output also accepts a JSONata expression directly. Default: - $states.result or $states.errorOutput

Methods

add_catch(handler, *, assign=None, errors=None, outputs=None, result_path=None)

Add a recovery handler for this state.

When a particular error occurs, execution will continue at the error handler instead of failing the state machine execution.

Parameters:

  • handler (IChainable) –

  • assign (Optional[Mapping[str, Any]]) – Workflow variables to store in this step. Using workflow variables, you can store data in a step and retrieve that data in future steps. Default: - Not assign variables

  • errors (Optional[Sequence[str]]) – Errors to recover from by going to the given state. A list of error strings to retry, which can be either predefined errors (for example Errors.NoChoiceMatched) or a self-defined error. Default: All errors

  • outputs (Any) – This option for JSONata only. When you use JSONPath, then the state ignores this property. Used to specify and transform output from the state. When specified, the value overrides the state output default. The output field accepts any JSON value (object, array, string, number, boolean, null). Any string value, including those inside objects or arrays, will be evaluated as JSONata if surrounded by {% %} characters. Output also accepts a JSONata expression directly. Default: - $states.result or $states.errorOutput

  • result_path (Optional[str]) – JSONPath expression to indicate where to inject the error data. May also be the special value JsonPath.DISCARD, which will cause the error data to be discarded. Default: $

Return type:

Parallel

add_prefix(x)

Add a prefix to the stateId of this state.

Parameters:

x (str) –

Return type:

None

add_retry(*, backoff_rate=None, errors=None, interval=None, jitter_strategy=None, max_attempts=None, max_delay=None)

Add retry configuration for this state.

This controls if and how the execution will be retried if a particular error occurs.

Parameters:

  • backoff_rate (Union[int, float, None]) – Multiplication for how much longer the wait interval gets on every retry. Default: 2

  • errors (Optional[Sequence[str]]) – Errors to retry. A list of error strings to retry, which can be either predefined errors (for example Errors.NoChoiceMatched) or a self-defined error. Default: All errors

  • interval (Optional[Duration]) – How many seconds to wait initially before retrying. Default: Duration.seconds(1)

  • jitter_strategy (Optional[JitterType]) – Introduces a randomization over the retry interval. Default: - No jitter strategy

  • max_attempts (Union[int, float, None]) – How many times to retry this particular error. May be 0 to disable retry for specific errors (in case you have a catch-all retry policy). Default: 3

  • max_delay (Optional[Duration]) – Maximum limit on retry interval growth during exponential backoff. Default: - No max delay

Return type:

Parallel

bind_to_graph(graph)

Overwrites State.bindToGraph. Adds branches to the Parallel state here so that any necessary prefixes are appended first.

Parameters:

graph (StateGraph) –

Return type:

None

branch(*branches)

Define one or more branches to run in parallel.

Parameters:

branches (IChainable) –

Return type:

Parallel

next(next)

Continue normal execution with the given state.

Parameters:

next (IChainable) –

Return type:

Chain

to_state_json(top_level_query_language=None)

Return the Amazon States Language object for this state.

Parameters:

top_level_query_language (Optional[QueryLanguage]) –

Return type:

Mapping[Any, Any]

to_string()

Returns a string representation of this construct.

Return type:

str

Attributes

end_states

Continuable states of this Chainable.

id

Descriptive identifier for this chainable.

node

The tree node.

start_state

First state of this Chainable.

state_id

Tokenized string that evaluates to the state’s ID.

Static Methods

classmethod filter_nextables(states)

Return only the states that allow chaining from an array of states.

Parameters:

states (Sequence[State]) –

Return type:

List[INextable]

classmethod find_reachable_end_states(start, *, include_error_handlers=None)

Find the set of end states states reachable through transitions from the given start state.

Parameters:

  • start (State) –

  • include_error_handlers (Optional[bool]) – Whether or not to follow error-handling transitions. Default: false

Return type:

List[State]

classmethod find_reachable_states(start, *, include_error_handlers=None)

Find the set of states reachable through transitions from the given start state.

This does not retrieve states from within sub-graphs, such as states within a Parallel state’s branch.

Parameters:

  • start (State) –

  • include_error_handlers (Optional[bool]) – Whether or not to follow error-handling transitions. Default: false

Return type:

List[State]

classmethod is_construct(x)

Checks if x is a construct.

Use this method instead of instanceof to properly detect Construct instances, even when the construct library is symlinked.

Explanation: in JavaScript, multiple copies of the constructs library on disk are seen as independent, completely different libraries. As a consequence, the class Construct in each copy of the constructs library is seen as a different class, and an instance of one class will not test as instanceof the other class. npm install will not create installations like this, but users may manually symlink construct libraries together or use a monorepo tool: in those cases, multiple copies of the constructs library can be accidentally installed, and instanceof will behave unpredictably. It is safest to avoid using instanceof, and using this type-testing method instead.

Parameters:

x (Any) – Any object.

Return type:

bool

Returns:

true if x is an object created from a class which extends Construct.

classmethod json_path(scope, id, *, result_path=None, result_selector=None, comment=None, query_language=None, state_name=None, assign=None, input_path=None, output_path=None)

Define a Parallel state using JSONPath in the state machine.

A Parallel state can be used to run one or more state machines at the same time.

The Result of a Parallel state is an array of the results of its substatemachines.

Parameters:

  • scope (Construct) –

  • id (str) –

  • result_path (Optional[str]) – JSONPath expression to indicate where to inject the state’s output. May also be the special value JsonPath.DISCARD, which will cause the state’s input to become its output. Default: $

  • result_selector (Optional[Mapping[str, Any]]) – The JSON that will replace the state’s raw result and become the effective result before ResultPath is applied. You can use ResultSelector to create a payload with values that are static or selected from the state’s raw result. Default: - None

  • comment (Optional[str]) – A comment describing this state. Default: No comment

  • query_language (Optional[QueryLanguage]) – The name of the query language used by the state. If the state does not contain a queryLanguage field, then it will use the query language specified in the top-level queryLanguage field. Default: - JSONPath

  • state_name (Optional[str]) – Optional name for this state. Default: - The construct ID will be used as state name

  • assign (Optional[Mapping[str, Any]]) – Workflow variables to store in this step. Using workflow variables, you can store data in a step and retrieve that data in future steps. Default: - Not assign variables

  • input_path (Optional[str]) – JSONPath expression to select part of the state to be the input to this state. May also be the special value JsonPath.DISCARD, which will cause the effective input to be the empty object {}. Default: $

  • output_path (Optional[str]) – JSONPath expression to select part of the state to be the output to this state. May also be the special value JsonPath.DISCARD, which will cause the effective output to be the empty object {}. Default: $

Return type:

Parallel

classmethod jsonata(scope, id, *, arguments=None, comment=None, query_language=None, state_name=None, assign=None, outputs=None)

Define a Parallel state using JSONata in the state machine.

A Parallel state can be used to run one or more state machines at the same time.

The Result of a Parallel state is an array of the results of its substatemachines.

Parameters:

  • scope (Construct) –

  • id (str) –

  • arguments (Optional[Mapping[str, Any]]) – Parameters pass a collection of key-value pairs, either static values or JSONata expressions that select from the input. Default: No arguments

  • comment (Optional[str]) – A comment describing this state. Default: No comment

  • query_language (Optional[QueryLanguage]) – The name of the query language used by the state. If the state does not contain a queryLanguage field, then it will use the query language specified in the top-level queryLanguage field. Default: - JSONPath

  • state_name (Optional[str]) – Optional name for this state. Default: - The construct ID will be used as state name

  • assign (Optional[Mapping[str, Any]]) – Workflow variables to store in this step. Using workflow variables, you can store data in a step and retrieve that data in future steps. Default: - Not assign variables

  • outputs (Any) – Used to specify and transform output from the state. When specified, the value overrides the state output default. The output field accepts any JSON value (object, array, string, number, boolean, null). Any string value, including those inside objects or arrays, will be evaluated as JSONata if surrounded by {% %} characters. Output also accepts a JSONata expression directly. Default: - $states.result or $states.errorOutput

Return type:

Parallel

classmethod prefix_states(root, prefix)

Add a prefix to the stateId of all States found in a construct tree.

Parameters:
Return type:

None