amazonka-swf-0.0.5: Amazon Simple Workflow Service SDK.

Safe HaskellNone
LanguageHaskell2010

Network.AWS.SWF.PollForDecisionTask

Contents

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 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 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 SWFWorkflows.

http://docs.aws.amazon.com/amazonswf/latest/apireference/API_PollForDecisionTask.html

Synopsis

Request

Request constructor

Request lenses

pfdtDomain :: Lens' PollForDecisionTask Text Source

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

pfdtIdentity :: Lens' PollForDecisionTask (Maybe Text) Source

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.

pfdtMaximumPageSize :: Lens' PollForDecisionTask (Maybe Natural) Source

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.

pfdtNextPageToken :: Lens' PollForDecisionTask (Maybe Text) Source

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.

.

pfdtReverseOrder :: Lens' PollForDecisionTask (Maybe Bool) Source

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.

pfdtTaskList :: Lens' PollForDecisionTask TaskList Source

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".

Response

Response constructor

Response lenses

pfdtrEvents :: Lens' PollForDecisionTaskResponse [HistoryEvent] Source

A paginated list of history events of the workflow execution. The decider uses this during the processing of the decision task.

pfdtrNextPageToken :: Lens' PollForDecisionTaskResponse (Maybe Text) Source

Returns a value if the results are paginated. To get the next page of results, repeat the request specifying this token and all other arguments unchanged.

pfdtrPreviousStartedEventId :: Lens' PollForDecisionTaskResponse (Maybe Integer) Source

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.

pfdtrTaskToken :: Lens' PollForDecisionTaskResponse Text Source

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.

pfdtrWorkflowExecution :: Lens' PollForDecisionTaskResponse WorkflowExecution Source

The workflow execution for which this decision task was created.

pfdtrWorkflowType :: Lens' PollForDecisionTaskResponse WorkflowType Source

The type of the workflow execution for which this decision task was created.