
poll-for-decision-task
**********************


DESCRIPTION
===========

Used by deciders to get a  DecisionTask from the specified decision
"--task-list" . 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.

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

Warning: 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 "--next-page-
  token" returned by the initial call. Note that you do **not** call
  "get-workflow-execution-history" with this "--next-page-token" .
  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.

* 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 .


SYNOPSIS
========

   aws swf poll-for-decision-task
     --domain <value>
     --task-list <value>
     [--next-page-token <value>]
     [--reverse-order ]
     [--maximum-page-size <value>]
     [--identity <value>]


REQUIRED PARAMETERS
===================

"--domain"  (string)
   The name of the --domain containing the task lists to poll.

"--task-list"  (structure)
   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)

   *Parameter Syntax*

      {
        "name": "string"
      }


OPTIONAL PARAMETERS
===================

"--next-page-token"  (string)
   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.

   Note: The "--next-page-token" 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 "--next-page-
     token" ) to retrieve the next page of history records. Calling
     poll-for-decision-task with a "--next-page-token" will not return
     a new decision task.

   .

"--reverse-order"  (boolean)
   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.

"--maximum-page-size"  (integer)
   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 --maximum-page-size specified.

"--identity"  (string)
   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.
