Copyright | (c) 2013-2015 Brendan Hay |
---|---|
License | Mozilla Public License, v. 2.0. |
Maintainer | Brendan Hay <brendan.g.hay@gmail.com> |
Stability | auto-generated |
Portability | non-portable (GHC extensions) |
Safe Haskell | None |
Language | Haskell2010 |
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. The associated event attribute's cause parameter will be set to OPERATION_NOT_PERMITTED. For details and example IAM policies, see Using IAM to Manage Access to Amazon SWF Workflows.
See: AWS API Reference for PollForDecisionTask.
This operation returns paginated results.
- pollForDecisionTask :: Text -> TaskList -> PollForDecisionTask
- data PollForDecisionTask
- pfdtNextPageToken :: Lens' PollForDecisionTask (Maybe Text)
- pfdtReverseOrder :: Lens' PollForDecisionTask (Maybe Bool)
- pfdtMaximumPageSize :: Lens' PollForDecisionTask (Maybe Natural)
- pfdtIdentity :: Lens' PollForDecisionTask (Maybe Text)
- pfdtDomain :: Lens' PollForDecisionTask Text
- pfdtTaskList :: Lens' PollForDecisionTask TaskList
- pollForDecisionTaskResponse :: Int -> Text -> Integer -> WorkflowExecution -> WorkflowType -> PollForDecisionTaskResponse
- data PollForDecisionTaskResponse
- pfdtrsNextPageToken :: Lens' PollForDecisionTaskResponse (Maybe Text)
- pfdtrsPreviousStartedEventId :: Lens' PollForDecisionTaskResponse (Maybe Integer)
- pfdtrsResponseStatus :: Lens' PollForDecisionTaskResponse Int
- pfdtrsTaskToken :: Lens' PollForDecisionTaskResponse Text
- pfdtrsStartedEventId :: Lens' PollForDecisionTaskResponse Integer
- pfdtrsWorkflowExecution :: Lens' PollForDecisionTaskResponse WorkflowExecution
- pfdtrsWorkflowType :: Lens' PollForDecisionTaskResponse WorkflowType
- pfdtrsEvents :: Lens' PollForDecisionTaskResponse [HistoryEvent]
Creating a Request
Creates a value of PollForDecisionTask
with the minimum fields required to make a request.
Use one of the following lenses to modify other fields as desired:
data PollForDecisionTask Source
See: pollForDecisionTask
smart constructor.
Request Lenses
pfdtNextPageToken :: Lens' PollForDecisionTask (Maybe Text) Source
If a NextPageToken
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 nextPageToken
. Keep all other
arguments unchanged.
The configured maximumPageSize
determines how many results can be
returned in a single call.
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.
.
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.
pfdtMaximumPageSize :: Lens' PollForDecisionTask (Maybe Natural) Source
The maximum number of results that will be returned per call.
nextPageToken
can be used to obtain futher pages of results. The
default is 1000, which is the maximum allowed page size. You can,
however, specify a page size smaller than the maximum.
This is an upper limit only; the actual number of results returned per call may be fewer than the specified maximum.
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.
pfdtDomain :: Lens' PollForDecisionTask Text Source
The name of the domain containing the task lists to poll.
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 quotarnquot.
Destructuring the Response
pollForDecisionTaskResponse Source
:: Int | |
-> Text | |
-> Integer | |
-> WorkflowExecution | |
-> WorkflowType | |
-> PollForDecisionTaskResponse |
Creates a value of PollForDecisionTaskResponse
with the minimum fields required to make a request.
Use one of the following lenses to modify other fields as desired:
data PollForDecisionTaskResponse Source
A structure that represents a decision task. Decision tasks are sent to deciders in order for them to make decisions.
See: pollForDecisionTaskResponse
smart constructor.
Response Lenses
pfdtrsNextPageToken :: Lens' PollForDecisionTaskResponse (Maybe Text) Source
If a NextPageToken
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 nextPageToken
. Keep all other
arguments unchanged.
The configured maximumPageSize
determines how many results can be
returned in a single call.
pfdtrsPreviousStartedEventId :: 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.
pfdtrsResponseStatus :: Lens' PollForDecisionTaskResponse Int Source
The response status code.
pfdtrsTaskToken :: 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.
pfdtrsStartedEventId :: Lens' PollForDecisionTaskResponse Integer Source
The ID of the DecisionTaskStarted
event recorded in the history.
pfdtrsWorkflowExecution :: Lens' PollForDecisionTaskResponse WorkflowExecution Source
The workflow execution for which this decision task was created.
pfdtrsWorkflowType :: Lens' PollForDecisionTaskResponse WorkflowType Source
The type of the workflow execution for which this decision task was created.
pfdtrsEvents :: 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.