poll_for_decision_task ( $opt )

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

If the caller does not have sufficient permissions to invoke the action, or the parameter values fall outside the specified constraints, the action fails by throwing OperationNotPermitted. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows.

Access

public

Parameters

Parameter

Type

Required

Description

$opt

array

Optional

An associative array of parameters that can have the following keys:

  • domain - string - Required - The name of the domain containing the task lists to poll.
  • taskList - array - Required - Specifies the task list to poll for decision tasks. The specified string must not start or end with whitespace. It must not contain a : (colon), / (slash), | (vertical bar), or any control characters (\u0000-\u001f | \u007f - \u009f). Also, it must not contain the literal string “arn”.
    • name - string - Required - The name of the task list.
  • identity - string - Optional - 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 - string - Optional - If on a previous call to this method a NextPageToken was returned, the results are being paginated. To get the next page of results, repeat the call with the returned token and all other arguments unchanged.

    The nextPageToken returned by this action cannot be used with GetWorkflowExecutionHistory to get the next page. You must call PollForDecisionTask again (with the nextPageToken) to retrieve the next page of history records. Calling PollForDecisionTask with a nextPageToken will not return a new decision task.

    .
  • maximumPageSize - integer - Optional - The maximum number of history events returned in each page. The default is 100, but the caller can override this value to a page size smaller than the default. You cannot specify a page size greater than 100. Note that the number of events may be less than the maxiumum page size, in which case, the returned page will have fewer results than the maximumPageSize specified.
  • reverseOrder - boolean - Optional - 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.
  • curlopts - array - Optional - A set of values to pass directly into curl_setopt(), where the key is a pre-defined CURLOPT_* constant.
  • returnCurlHandle - boolean - Optional - A private toggle specifying that the cURL handle be returned rather than actually completing the request. This toggle is useful for manually managed batch requests.

Returns

Type

Description

CFResponse

A CFResponse object containing a parsed HTTP response.

Source

Method defined in services/swf.class.php | Toggle source view (6 lines) | View on GitHub

public function poll_for_decision_task($opt = null)
{
    if (!$opt) $opt = array();
    
    return $this->authenticate('PollForDecisionTask', $opt);
}

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