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v1

latestOpenAPI 3.0.0Apache 2.0 License2026-07-1437225343.0 KB

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 PollForDecisionTask using the nextPageToken returned by the initial call. Note that you do not call GetWorkflowExecutionHistory with this nextPageToken. Instead, call PollForDecisionTask 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.

post/#X-Amz-Target=SimpleWorkflowService.PollForDecisionTask

Query parameters

maximumPageSizestring

Pagination limit

nextPageTokenstring

Pagination token

Headers

X-Amz-Target'SimpleWorkflowService.PollForDecisionTask' required

Request body

domainstring required

The name of the domain containing the task lists to poll.

identitystring

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.

nextPageTokenstring
<p>If <code>NextPageToken</code> is returned there are more results available. The value of <code>NextPageToken</code> 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 60 seconds. Using an expired pagination token will return a <code>400</code> error: "<code>Specified token has exceeded its maximum lifetime</code>". </p> <p>The configured <code>maximumPageSize</code> determines how many results can be returned in a single call. </p> <note> <p>The <code>nextPageToken</code> returned by this action cannot be used with <a>GetWorkflowExecutionHistory</a> to get the next page. You must call <a>PollForDecisionTask</a> again (with the <code>nextPageToken</code>) to retrieve the next page of history records. Calling <a>PollForDecisionTask</a> with a <code>nextPageToken</code> doesn't return a new decision task.</p> </note>
maximumPageSizeinteger
<p>The maximum number of results that are returned per call. Use <code>nextPageToken</code> to obtain further pages of results. </p> <p>This is an upper limit only; the actual number of results returned per call may be fewer than the specified maximum.</p>
reverseOrderboolean

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

Response

Success

taskTokenstring required

The opaque string used as a handle on the task. This token is used by workers to communicate progress and response information back to the system about the task.

startedEventIdinteger required

The ID of the <code>DecisionTaskStarted</code> event recorded in the history.

nextPageTokenstring
<p>If a <code>NextPageToken</code> was returned by a previous call, there are more results available. To retrieve the next page of results, make the call again using the returned token in <code>nextPageToken</code>. Keep all other arguments unchanged.</p> <p>The configured <code>maximumPageSize</code> determines how many results can be returned in a single call.</p>
previousStartedEventIdinteger

The ID of the DecisionTaskStarted event of the previous decision task of this workflow execution that was processed by the decider. This can be used to determine the events in the history new since the last decision task received by the decider.