# GetActivityTask
<a name="API_GetActivityTask"></a>

Used by workers to retrieve a task (with the specified activity ARN) which has been scheduled for execution by a running state machine. This initiates a long poll, where the service holds the HTTP connection open and responds as soon as a task becomes available (i.e. an execution of a task of this type is needed.) The maximum time the service holds on to the request before responding is 60 seconds. If no task is available within 60 seconds, the poll returns a `taskToken` with a null string.

**Note**  
This API action isn't logged in CloudTrail.

**Important**  
Workers should set their client side socket timeout to at least 65 seconds (5 seconds higher than the maximum time the service may hold the poll request).  
Polling with `GetActivityTask` can cause latency in some implementations. See [Avoid Latency When Polling for Activity Tasks](https://docs.amazonaws.cn/step-functions/latest/dg/bp-activity-pollers.html) in the Step Functions Developer Guide.

## Request Syntax
<a name="API_GetActivityTask_RequestSyntax"></a>

```
{
   "activityArn": "string",
   "workerName": "string"
}
```

## Request Parameters
<a name="API_GetActivityTask_RequestParameters"></a>

For information about the parameters that are common to all actions, see [Common Parameters](CommonParameters.md).

The request accepts the following data in JSON format.

 ** [activityArn](#API_GetActivityTask_RequestSyntax) **   <a name="StepFunctions-GetActivityTask-request-activityArn"></a>
The Amazon Resource Name (ARN) of the activity to retrieve tasks from (assigned when you create the task using [CreateActivity](API_CreateActivity.md).)  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 256.  
Required: Yes

 ** [workerName](#API_GetActivityTask_RequestSyntax) **   <a name="StepFunctions-GetActivityTask-request-workerName"></a>
You can provide an arbitrary name in order to identify the worker that the task is assigned to. This name is used when it is logged in the execution history.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 80.  
Required: No

## Response Syntax
<a name="API_GetActivityTask_ResponseSyntax"></a>

```
{
   "input": "string",
   "taskToken": "string"
}
```

## Response Elements
<a name="API_GetActivityTask_ResponseElements"></a>

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

 ** [input](#API_GetActivityTask_ResponseSyntax) **   <a name="StepFunctions-GetActivityTask-response-input"></a>
The string that contains the JSON input data for the task. Length constraints apply to the payload size, and are expressed as bytes in UTF-8 encoding.  
Type: String  
Length Constraints: Maximum length of 1048576.

 ** [taskToken](#API_GetActivityTask_ResponseSyntax) **   <a name="StepFunctions-GetActivityTask-response-taskToken"></a>
A token that identifies the scheduled task. This token must be copied and included in subsequent calls to [SendTaskHeartbeat](API_SendTaskHeartbeat.md), [SendTaskSuccess](API_SendTaskSuccess.md) or [SendTaskFailure](API_SendTaskFailure.md) in order to report the progress or completion of the task.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 2048.

## Errors
<a name="API_GetActivityTask_Errors"></a>

For information about the errors that are common to all actions, see [Common Error Types](CommonErrors.md).

 ** ActivityDoesNotExist **   
The specified activity does not exist.  
HTTP Status Code: 400

 ** ActivityWorkerLimitExceeded **   
The maximum number of workers concurrently polling for activity tasks has been reached.  
HTTP Status Code: 400

 ** InvalidArn **   
The provided Amazon Resource Name (ARN) is not valid.  
HTTP Status Code: 400

 ** KmsAccessDeniedException **   
Either your Amazon KMS key policy or API caller does not have the required permissions.  
HTTP Status Code: 400

 ** KmsInvalidStateException **   
The Amazon KMS key is not in valid state, for example: Disabled or Deleted.    
 ** kmsKeyState **   
Current status of the Amazon KMS; key. For example: `DISABLED`, `PENDING_DELETION`, `PENDING_IMPORT`, `UNAVAILABLE`, `CREATING`.
HTTP Status Code: 400

 ** KmsThrottlingException **   
Received when Amazon KMS returns `ThrottlingException` for a Amazon KMS call that Step Functions makes on behalf of the caller.  
HTTP Status Code: 400

## See Also
<a name="API_GetActivityTask_SeeAlso"></a>

For more information about using this API in one of the language-specific Amazon SDKs, see the following:
+  [Amazon Command Line Interface V2](https://docs.amazonaws.cn/goto/cli2/states-2016-11-23/GetActivityTask) 
+  [Amazon SDK for .NET V4](https://docs.amazonaws.cn/goto/DotNetSDKV4/states-2016-11-23/GetActivityTask) 
+  [Amazon SDK for C\$1\$1](https://docs.amazonaws.cn/goto/SdkForCpp/states-2016-11-23/GetActivityTask) 
+  [Amazon SDK for Go v2](https://docs.amazonaws.cn/goto/SdkForGoV2/states-2016-11-23/GetActivityTask) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/states-2016-11-23/GetActivityTask) 
+  [Amazon SDK for JavaScript V3](https://docs.amazonaws.cn/goto/SdkForJavaScriptV3/states-2016-11-23/GetActivityTask) 
+  [Amazon SDK for Kotlin](https://docs.amazonaws.cn/goto/SdkForKotlin/states-2016-11-23/GetActivityTask) 
+  [Amazon SDK for PHP V3](https://docs.amazonaws.cn/goto/SdkForPHPV3/states-2016-11-23/GetActivityTask) 
+  [Amazon SDK for Python](https://docs.amazonaws.cn/goto/boto3/states-2016-11-23/GetActivityTask) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/states-2016-11-23/GetActivityTask)