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Poll for Decision Task

swf_poll_for_decision_task R Documentation

Used by deciders to get a DecisionTask from the specified decision taskList

Description

Used by deciders to get a DecisionTask from the specified decision taskList. A decision task may be returned for any open workflow execution that is using the specified task list. The task includes a paginated view of the history of the workflow execution. The decider should use the workflow type and the history to determine how to properly handle the task.

This action initiates a long poll, where the service holds the HTTP connection open and responds as soon a task becomes available. If no decision task is available in the specified task list before the timeout of 60 seconds expires, an empty result is returned. An empty result, in this context, means that a DecisionTask is returned, but that the value of taskToken is an empty string.

Deciders should set their client side socket timeout to at least 70 seconds (10 seconds higher than the timeout).

Because the number of workflow history events for a single workflow execution might be very large, the result returned might be split up across a number of pages. To retrieve subsequent pages, make additional calls to poll_for_decision_task using the nextPageToken returned by the initial call. Note that you do not call get_workflow_execution_history with this nextPageToken. Instead, call poll_for_decision_task again.

Access Control

You can use IAM policies to control this action's access to Amazon SWF resources as follows:

  • Use a Resource element with the domain name to limit the action to only specified domains.

  • Use an Action element to allow or deny permission to call this action.

  • Constrain the taskList.name parameter by using a Condition element with the swf:taskList.name key to allow the action to access only certain task lists.

If the caller doesn't have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails. The associated event attribute's cause parameter is set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows in the Amazon SWF Developer Guide.

Usage

swf_poll_for_decision_task(domain, taskList, identity, nextPageToken,
  maximumPageSize, reverseOrder, startAtPreviousStartedEvent)

Arguments

domain

[required] The name of the domain containing the task lists to poll.

taskList

[required] Specifies the task list to poll for decision tasks.

The specified string must not contain a : (colon), / (slash), | (vertical bar), or any control characters (⁠U+0000`-`U+001f⁠ | ⁠U+007f`-`U+009f⁠). Also, it must not be the literal string arn.

identity

Identity of the decider making the request, which is recorded in the DecisionTaskStarted event in the workflow history. This enables diagnostic tracing when problems arise. The form of this identity is user defined.

nextPageToken

If NextPageToken is returned there are more results available. The value of NextPageToken is a unique pagination token for each page. Make the call again using the returned token to retrieve the next page. Keep all other arguments unchanged. Each pagination token expires after 24 hours. Using an expired pagination token will return a 400 error: "⁠Specified token has exceeded its maximum lifetime⁠".

The configured maximumPageSize determines how many results can be returned in a single call.

The nextPageToken returned by this action cannot be used with get_workflow_execution_history to get the next page. You must call poll_for_decision_task again (with the nextPageToken) to retrieve the next page of history records. Calling poll_for_decision_task with a nextPageToken doesn't return a new decision task.

maximumPageSize

The maximum number of results that are returned per call. Use nextPageToken to obtain further pages of results.

This is an upper limit only; the actual number of results returned per call may be fewer than the specified maximum.

reverseOrder

When set to true, returns the events in reverse order. By default the results are returned in ascending order of the eventTimestamp of the events.

startAtPreviousStartedEvent

When set to true, returns the events with eventTimestamp greater than or equal to eventTimestamp of the most recent DecisionTaskStarted event. By default, this parameter is set to false.

Value

A list with the following syntax: 

list(
  taskToken = "string",
  startedEventId = 123,
  workflowExecution = list(
    workflowId = "string",
    runId = "string"
  ),
  workflowType = list(
    name = "string",
    version = "string"
  ),
  events = list(
    list(
      eventTimestamp = as.POSIXct(
        "2015-01-01"
      ),
      eventType = "WorkflowExecutionStarted"|"WorkflowExecutionCancelRequested"|"WorkflowExecutionCompleted"|"CompleteWorkflowExecutionFailed"|"WorkflowExecutionFailed"|"FailWorkflowExecutionFailed"|"WorkflowExecutionTimedOut"|"WorkflowExecutionCanceled"|"CancelWorkflowExecutionFailed"|"WorkflowExecutionContinuedAsNew"|"ContinueAsNewWorkflowExecutionFailed"|"WorkflowExecutionTerminated"|"DecisionTaskScheduled"|"DecisionTaskStarted"|"DecisionTaskCompleted"|"DecisionTaskTimedOut"|"ActivityTaskScheduled"|"ScheduleActivityTaskFailed"|"ActivityTaskStarted"|"ActivityTaskCompleted"|"ActivityTaskFailed"|"ActivityTaskTimedOut"|"ActivityTaskCanceled"|"ActivityTaskCancelRequested"|"RequestCancelActivityTaskFailed"|"WorkflowExecutionSignaled"|"MarkerRecorded"|"RecordMarkerFailed"|"TimerStarted"|"StartTimerFailed"|"TimerFired"|"TimerCanceled"|"CancelTimerFailed"|"StartChildWorkflowExecutionInitiated"|"StartChildWorkflowExecutionFailed"|"ChildWorkflowExecutionStarted"|"ChildWorkflowExecutionCompleted"|"ChildWorkflowExecutionFailed"|"ChildWorkflowExecutionTimedOut"|"ChildWorkflowExecutionCanceled"|"ChildWorkflowExecutionTerminated"|"SignalExternalWorkflowExecutionInitiated"|"SignalExternalWorkflowExecutionFailed"|"ExternalWorkflowExecutionSignaled"|"RequestCancelExternalWorkflowExecutionInitiated"|"RequestCancelExternalWorkflowExecutionFailed"|"ExternalWorkflowExecutionCancelRequested"|"LambdaFunctionScheduled"|"LambdaFunctionStarted"|"LambdaFunctionCompleted"|"LambdaFunctionFailed"|"LambdaFunctionTimedOut"|"ScheduleLambdaFunctionFailed"|"StartLambdaFunctionFailed",
      eventId = 123,
      workflowExecutionStartedEventAttributes = list(
        input = "string",
        executionStartToCloseTimeout = "string",
        taskStartToCloseTimeout = "string",
        childPolicy = "TERMINATE"|"REQUEST_CANCEL"|"ABANDON",
        taskList = list(
          name = "string"
        ),
        taskPriority = "string",
        workflowType = list(
          name = "string",
          version = "string"
        ),
        tagList = list(
          "string"
        ),
        continuedExecutionRunId = "string",
        parentWorkflowExecution = list(
          workflowId = "string",
          runId = "string"
        ),
        parentInitiatedEventId = 123,
        lambdaRole = "string"
      ),
      workflowExecutionCompletedEventAttributes = list(
        result = "string",
        decisionTaskCompletedEventId = 123
      ),
      completeWorkflowExecutionFailedEventAttributes = list(
        cause = "UNHANDLED_DECISION"|"OPERATION_NOT_PERMITTED",
        decisionTaskCompletedEventId = 123
      ),
      workflowExecutionFailedEventAttributes = list(
        reason = "string",
        details = "string",
        decisionTaskCompletedEventId = 123
      ),
      failWorkflowExecutionFailedEventAttributes = list(
        cause = "UNHANDLED_DECISION"|"OPERATION_NOT_PERMITTED",
        decisionTaskCompletedEventId = 123
      ),
      workflowExecutionTimedOutEventAttributes = list(
        timeoutType = "START_TO_CLOSE",
        childPolicy = "TERMINATE"|"REQUEST_CANCEL"|"ABANDON"
      ),
      workflowExecutionCanceledEventAttributes = list(
        details = "string",
        decisionTaskCompletedEventId = 123
      ),
      cancelWorkflowExecutionFailedEventAttributes = list(
        cause = "UNHANDLED_DECISION"|"OPERATION_NOT_PERMITTED",
        decisionTaskCompletedEventId = 123
      ),
      workflowExecutionContinuedAsNewEventAttributes = list(
        input = "string",
        decisionTaskCompletedEventId = 123,
        newExecutionRunId = "string",
        executionStartToCloseTimeout = "string",
        taskList = list(
          name = "string"
        ),
        taskPriority = "string",
        taskStartToCloseTimeout = "string",
        childPolicy = "TERMINATE"|"REQUEST_CANCEL"|"ABANDON",
        tagList = list(
          "string"
        ),
        workflowType = list(
          name = "string",
          version = "string"
        ),
        lambdaRole = "string"
      ),
      continueAsNewWorkflowExecutionFailedEventAttributes = list(
        cause = "UNHANDLED_DECISION"|"WORKFLOW_TYPE_DEPRECATED"|"WORKFLOW_TYPE_DOES_NOT_EXIST"|"DEFAULT_EXECUTION_START_TO_CLOSE_TIMEOUT_UNDEFINED"|"DEFAULT_TASK_START_TO_CLOSE_TIMEOUT_UNDEFINED"|"DEFAULT_TASK_LIST_UNDEFINED"|"DEFAULT_CHILD_POLICY_UNDEFINED"|"CONTINUE_AS_NEW_WORKFLOW_EXECUTION_RATE_EXCEEDED"|"OPERATION_NOT_PERMITTED",
        decisionTaskCompletedEventId = 123
      ),
      workflowExecutionTerminatedEventAttributes = list(
        reason = "string",
        details = "string",
        childPolicy = "TERMINATE"|"REQUEST_CANCEL"|"ABANDON",
        cause = "CHILD_POLICY_APPLIED"|"EVENT_LIMIT_EXCEEDED"|"OPERATOR_INITIATED"
      ),
      workflowExecutionCancelRequestedEventAttributes = list(
        externalWorkflowExecution = list(
          workflowId = "string",
          runId = "string"
        ),
        externalInitiatedEventId = 123,
        cause = "CHILD_POLICY_APPLIED"
      ),
      decisionTaskScheduledEventAttributes = list(
        taskList = list(
          name = "string"
        ),
        taskPriority = "string",
        startToCloseTimeout = "string",
        scheduleToStartTimeout = "string"
      ),
      decisionTaskStartedEventAttributes = list(
        identity = "string",
        scheduledEventId = 123
      ),
      decisionTaskCompletedEventAttributes = list(
        executionContext = "string",
        scheduledEventId = 123,
        startedEventId = 123,
        taskList = list(
          name = "string"
        ),
        taskListScheduleToStartTimeout = "string"
      ),
      decisionTaskTimedOutEventAttributes = list(
        timeoutType = "START_TO_CLOSE"|"SCHEDULE_TO_START",
        scheduledEventId = 123,
        startedEventId = 123
      ),
      activityTaskScheduledEventAttributes = list(
        activityType = list(
          name = "string",
          version = "string"
        ),
        activityId = "string",
        input = "string",
        control = "string",
        scheduleToStartTimeout = "string",
        scheduleToCloseTimeout = "string",
        startToCloseTimeout = "string",
        taskList = list(
          name = "string"
        ),
        taskPriority = "string",
        decisionTaskCompletedEventId = 123,
        heartbeatTimeout = "string"
      ),
      activityTaskStartedEventAttributes = list(
        identity = "string",
        scheduledEventId = 123
      ),
      activityTaskCompletedEventAttributes = list(
        result = "string",
        scheduledEventId = 123,
        startedEventId = 123
      ),
      activityTaskFailedEventAttributes = list(
        reason = "string",
        details = "string",
        scheduledEventId = 123,
        startedEventId = 123
      ),
      activityTaskTimedOutEventAttributes = list(
        timeoutType = "START_TO_CLOSE"|"SCHEDULE_TO_START"|"SCHEDULE_TO_CLOSE"|"HEARTBEAT",
        scheduledEventId = 123,
        startedEventId = 123,
        details = "string"
      ),
      activityTaskCanceledEventAttributes = list(
        details = "string",
        scheduledEventId = 123,
        startedEventId = 123,
        latestCancelRequestedEventId = 123
      ),
      activityTaskCancelRequestedEventAttributes = list(
        decisionTaskCompletedEventId = 123,
        activityId = "string"
      ),
      workflowExecutionSignaledEventAttributes = list(
        signalName = "string",
        input = "string",
        externalWorkflowExecution = list(
          workflowId = "string",
          runId = "string"
        ),
        externalInitiatedEventId = 123
      ),
      markerRecordedEventAttributes = list(
        markerName = "string",
        details = "string",
        decisionTaskCompletedEventId = 123
      ),
      recordMarkerFailedEventAttributes = list(
        markerName = "string",
        cause = "OPERATION_NOT_PERMITTED",
        decisionTaskCompletedEventId = 123
      ),
      timerStartedEventAttributes = list(
        timerId = "string",
        control = "string",
        startToFireTimeout = "string",
        decisionTaskCompletedEventId = 123
      ),
      timerFiredEventAttributes = list(
        timerId = "string",
        startedEventId = 123
      ),
      timerCanceledEventAttributes = list(
        timerId = "string",
        startedEventId = 123,
        decisionTaskCompletedEventId = 123
      ),
      startChildWorkflowExecutionInitiatedEventAttributes = list(
        workflowId = "string",
        workflowType = list(
          name = "string",
          version = "string"
        ),
        control = "string",
        input = "string",
        executionStartToCloseTimeout = "string",
        taskList = list(
          name = "string"
        ),
        taskPriority = "string",
        decisionTaskCompletedEventId = 123,
        childPolicy = "TERMINATE"|"REQUEST_CANCEL"|"ABANDON",
        taskStartToCloseTimeout = "string",
        tagList = list(
          "string"
        ),
        lambdaRole = "string"
      ),
      childWorkflowExecutionStartedEventAttributes = list(
        workflowExecution = list(
          workflowId = "string",
          runId = "string"
        ),
        workflowType = list(
          name = "string",
          version = "string"
        ),
        initiatedEventId = 123
      ),
      childWorkflowExecutionCompletedEventAttributes = list(
        workflowExecution = list(
          workflowId = "string",
          runId = "string"
        ),
        workflowType = list(
          name = "string",
          version = "string"
        ),
        result = "string",
        initiatedEventId = 123,
        startedEventId = 123
      ),
      childWorkflowExecutionFailedEventAttributes = list(
        workflowExecution = list(
          workflowId = "string",
          runId = "string"
        ),
        workflowType = list(
          name = "string",
          version = "string"
        ),
        reason = "string",
        details = "string",
        initiatedEventId = 123,
        startedEventId = 123
      ),
      childWorkflowExecutionTimedOutEventAttributes = list(
        workflowExecution = list(
          workflowId = "string",
          runId = "string"
        ),
        workflowType = list(
          name = "string",
          version = "string"
        ),
        timeoutType = "START_TO_CLOSE",
        initiatedEventId = 123,
        startedEventId = 123
      ),
      childWorkflowExecutionCanceledEventAttributes = list(
        workflowExecution = list(
          workflowId = "string",
          runId = "string"
        ),
        workflowType = list(
          name = "string",
          version = "string"
        ),
        details = "string",
        initiatedEventId = 123,
        startedEventId = 123
      ),
      childWorkflowExecutionTerminatedEventAttributes = list(
        workflowExecution = list(
          workflowId = "string",
          runId = "string"
        ),
        workflowType = list(
          name = "string",
          version = "string"
        ),
        initiatedEventId = 123,
        startedEventId = 123
      ),
      signalExternalWorkflowExecutionInitiatedEventAttributes = list(
        workflowId = "string",
        runId = "string",
        signalName = "string",
        input = "string",
        decisionTaskCompletedEventId = 123,
        control = "string"
      ),
      externalWorkflowExecutionSignaledEventAttributes = list(
        workflowExecution = list(
          workflowId = "string",
          runId = "string"
        ),
        initiatedEventId = 123
      ),
      signalExternalWorkflowExecutionFailedEventAttributes = list(
        workflowId = "string",
        runId = "string",
        cause = "UNKNOWN_EXTERNAL_WORKFLOW_EXECUTION"|"SIGNAL_EXTERNAL_WORKFLOW_EXECUTION_RATE_EXCEEDED"|"OPERATION_NOT_PERMITTED",
        initiatedEventId = 123,
        decisionTaskCompletedEventId = 123,
        control = "string"
      ),
      externalWorkflowExecutionCancelRequestedEventAttributes = list(
        workflowExecution = list(
          workflowId = "string",
          runId = "string"
        ),
        initiatedEventId = 123
      ),
      requestCancelExternalWorkflowExecutionInitiatedEventAttributes = list(
        workflowId = "string",
        runId = "string",
        decisionTaskCompletedEventId = 123,
        control = "string"
      ),
      requestCancelExternalWorkflowExecutionFailedEventAttributes = list(
        workflowId = "string",
        runId = "string",
        cause = "UNKNOWN_EXTERNAL_WORKFLOW_EXECUTION"|"REQUEST_CANCEL_EXTERNAL_WORKFLOW_EXECUTION_RATE_EXCEEDED"|"OPERATION_NOT_PERMITTED",
        initiatedEventId = 123,
        decisionTaskCompletedEventId = 123,
        control = "string"
      ),
      scheduleActivityTaskFailedEventAttributes = list(
        activityType = list(
          name = "string",
          version = "string"
        ),
        activityId = "string",
        cause = "ACTIVITY_TYPE_DEPRECATED"|"ACTIVITY_TYPE_DOES_NOT_EXIST"|"ACTIVITY_ID_ALREADY_IN_USE"|"OPEN_ACTIVITIES_LIMIT_EXCEEDED"|"ACTIVITY_CREATION_RATE_EXCEEDED"|"DEFAULT_SCHEDULE_TO_CLOSE_TIMEOUT_UNDEFINED"|"DEFAULT_TASK_LIST_UNDEFINED"|"DEFAULT_SCHEDULE_TO_START_TIMEOUT_UNDEFINED"|"DEFAULT_START_TO_CLOSE_TIMEOUT_UNDEFINED"|"DEFAULT_HEARTBEAT_TIMEOUT_UNDEFINED"|"OPERATION_NOT_PERMITTED",
        decisionTaskCompletedEventId = 123
      ),
      requestCancelActivityTaskFailedEventAttributes = list(
        activityId = "string",
        cause = "ACTIVITY_ID_UNKNOWN"|"OPERATION_NOT_PERMITTED",
        decisionTaskCompletedEventId = 123
      ),
      startTimerFailedEventAttributes = list(
        timerId = "string",
        cause = "TIMER_ID_ALREADY_IN_USE"|"OPEN_TIMERS_LIMIT_EXCEEDED"|"TIMER_CREATION_RATE_EXCEEDED"|"OPERATION_NOT_PERMITTED",
        decisionTaskCompletedEventId = 123
      ),
      cancelTimerFailedEventAttributes = list(
        timerId = "string",
        cause = "TIMER_ID_UNKNOWN"|"OPERATION_NOT_PERMITTED",
        decisionTaskCompletedEventId = 123
      ),
      startChildWorkflowExecutionFailedEventAttributes = list(
        workflowType = list(
          name = "string",
          version = "string"
        ),
        cause = "WORKFLOW_TYPE_DOES_NOT_EXIST"|"WORKFLOW_TYPE_DEPRECATED"|"OPEN_CHILDREN_LIMIT_EXCEEDED"|"OPEN_WORKFLOWS_LIMIT_EXCEEDED"|"CHILD_CREATION_RATE_EXCEEDED"|"WORKFLOW_ALREADY_RUNNING"|"DEFAULT_EXECUTION_START_TO_CLOSE_TIMEOUT_UNDEFINED"|"DEFAULT_TASK_LIST_UNDEFINED"|"DEFAULT_TASK_START_TO_CLOSE_TIMEOUT_UNDEFINED"|"DEFAULT_CHILD_POLICY_UNDEFINED"|"OPERATION_NOT_PERMITTED",
        workflowId = "string",
        initiatedEventId = 123,
        decisionTaskCompletedEventId = 123,
        control = "string"
      ),
      lambdaFunctionScheduledEventAttributes = list(
        id = "string",
        name = "string",
        control = "string",
        input = "string",
        startToCloseTimeout = "string",
        decisionTaskCompletedEventId = 123
      ),
      lambdaFunctionStartedEventAttributes = list(
        scheduledEventId = 123
      ),
      lambdaFunctionCompletedEventAttributes = list(
        scheduledEventId = 123,
        startedEventId = 123,
        result = "string"
      ),
      lambdaFunctionFailedEventAttributes = list(
        scheduledEventId = 123,
        startedEventId = 123,
        reason = "string",
        details = "string"
      ),
      lambdaFunctionTimedOutEventAttributes = list(
        scheduledEventId = 123,
        startedEventId = 123,
        timeoutType = "START_TO_CLOSE"
      ),
      scheduleLambdaFunctionFailedEventAttributes = list(
        id = "string",
        name = "string",
        cause = "ID_ALREADY_IN_USE"|"OPEN_LAMBDA_FUNCTIONS_LIMIT_EXCEEDED"|"LAMBDA_FUNCTION_CREATION_RATE_EXCEEDED"|"LAMBDA_SERVICE_NOT_AVAILABLE_IN_REGION",
        decisionTaskCompletedEventId = 123
      ),
      startLambdaFunctionFailedEventAttributes = list(
        scheduledEventId = 123,
        cause = "ASSUME_ROLE_FAILED",
        message = "string"
      )
    )
  ),
  nextPageToken = "string",
  previousStartedEventId = 123
)

Request syntax

svc$poll_for_decision_task(
  domain = "string",
  taskList = list(
    name = "string"
  ),
  identity = "string",
  nextPageToken = "string",
  maximumPageSize = 123,
  reverseOrder = TRUE|FALSE,
  startAtPreviousStartedEvent = TRUE|FALSE
)