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# 任务事件
<a name="events-jobs"></a>

当 AWS IoT 任务处于待处理状态、已完成或取消状态时，以及设备在运行作业时报告成功或失败时，作业服务将发布到 MQTT 协议上的保留主题。设备或管理和监控应用程序可以通过订阅这些主题来跟踪任务的状态。

**如何启用任务事件**  
来自 AWS IoT 任务服务的响应消息不会通过消息代理，也无法被其他客户端或规则订阅。要订阅与任务活动相关的消息，请使用 `notify` 和 `notify-next` 主题。有关任务主题的更多信息，请参阅 [任务主题](reserved-topics.md#reserved-topics-job)。

要收到任务更新的通知，请使用或使用 API 或 CLI 启用这些作业事件。 AWS 管理控制台有关更多信息，请参阅 [启用以下项的事件 AWS IoT](iot-events.md#iot-events-enable)。

**任务事件的工作原理**  
由于取消或删除任务可能需要一些时间，所以发送两条消息来指示请求的开始和结束。例如，当取消请求开始时，系统会向 `$aws/events/job/jobID/cancellation_in_progress` 主题发送一条消息。当取消请求完成时，系统会向 `$aws/events/job/jobID/canceled` 主题发送一条消息。

任务删除请求的过程与之相似。管理和监控应用程序可以订阅这些主题来跟踪任务的状态。有关发布和订阅 MQTT 主题的更多信息，请参阅 [设备通信协议](protocols.md)。

**任务事件类型**  
以下示例显示了不同类型的任务事件：

**Job Completed/Canceled/Deleted**  
当任务完成、取消、删除或正在取消或删除时， AWS IoT 作业服务会在 MQTT 主题上发布一条消息：  
+ `$aws/events/job/jobID/completed`
+ `$aws/events/job/jobID/canceled`
+ `$aws/events/job/jobID/deleted`
+ `$aws/events/job/jobID/cancellation_in_progress`
+ `$aws/events/job/jobID/deletion_in_progress`
`completed` 消息包含以下示例负载：  

```
{
  "eventType": "JOB",
  "eventId": "7364ffd1-8b65-4824-85d5-6c14686c97c6",
  "timestamp": 1234567890,
  "operation": "completed",
  "jobId": "27450507-bf6f-4012-92af-bb8a1c8c4484",
  "status": "COMPLETED",
  "targetSelection": "SNAPSHOT|CONTINUOUS",
  "targets": [
    "arn:aws:iot:us-east-1:123456789012:thing/a39f6f91-70cf-4bd2-a381-9c66df1a80d0",
    "arn:aws:iot:us-east-1:123456789012:thinggroup/2fc4c0a4-6e45-4525-a238-0fe8d3dd21bb"
  ],
  "description": "My Job Description",
  "completedAt": 1234567890123,
  "createdAt": 1234567890123,
  "lastUpdatedAt": 1234567890123,
  "jobProcessDetails": {
    "numberOfCanceledThings": 0,
    "numberOfRejectedThings": 0,
    "numberOfFailedThings": 0,
    "numberOfRemovedThings": 0,
    "numberOfSucceededThings": 3
  }
}
```
`canceled` 消息包含以下示例负载。  

```
{
  "eventType": "JOB",
  "eventId": "568d2ade-2e9c-46e6-a115-18afa1286b06",
  "timestamp": 1234567890,
  "operation": "canceled",
  "jobId": "4d2a531a-da2e-47bb-8b9e-ff5adcd53ef0",
  "status": "CANCELED",
  "targetSelection": "SNAPSHOT|CONTINUOUS",
  "targets": [
    "arn:aws:iot:us-east-1:123456789012:thing/Thing0-947b9c0c-ff10-4a80-b4b3-cd33d0145a0f",
    "arn:aws:iot:us-east-1:123456789012:thinggroup/ThingGroup1-95c644d5-1621-41a6-9aa5-ad2de581d18f"
  ],
  "description": "My job description",
  "createdAt": 1234567890123,
  "lastUpdatedAt": 1234567890123
}
```
`deleted` 消息包含以下示例负载。  

```
{
      "eventType": "JOB",
      "eventId": "568d2ade-2e9c-46e6-a115-18afa1286b06",
      "timestamp": 1234567890,
      "operation": "deleted",
      "jobId": "4d2a531a-da2e-47bb-8b9e-ff5adcd53ef0",
      "status": "DELETED",
      "targetSelection": "SNAPSHOT|CONTINUOUS",
      "targets": [
        "arn:aws:iot:us-east-1:123456789012:thing/Thing0-947b9c0c-ff10-4a80-b4b3-cd33d0145a0f",
        "arn:aws:iot:us-east-1:123456789012:thinggroup/ThingGroup1-95c644d5-1621-41a6-9aa5-ad2de581d18f"
      ],
      "description": "My job description",
      "createdAt": 1234567890123,
      "lastUpdatedAt": 1234567890123,
      "comment": "Comment for this operation"
    }
```
`cancellation_in_progress` 消息包含以下示例负载：  

```
{
      "eventType": "JOB",
      "eventId": "568d2ade-2e9c-46e6-a115-18afa1286b06",
      "timestamp": 1234567890,
      "operation": "cancellation_in_progress",
      "jobId": "4d2a531a-da2e-47bb-8b9e-ff5adcd53ef0",
      "status": "CANCELLATION_IN_PROGRESS",
      "targetSelection": "SNAPSHOT|CONTINUOUS",
      "targets": [
        "arn:aws:iot:us-east-1:123456789012:thing/Thing0-947b9c0c-ff10-4a80-b4b3-cd33d0145a0f",
        "arn:aws:iot:us-east-1:123456789012:thinggroup/ThingGroup1-95c644d5-1621-41a6-9aa5-ad2de581d18f"
      ],
      "description": "My job description",
      "createdAt": 1234567890123,
      "lastUpdatedAt": 1234567890123,
      "comment": "Comment for this operation"
    }
```
`deletion_in_progress` 消息包含以下示例负载：  

```
{
      "eventType": "JOB",
      "eventId": "568d2ade-2e9c-46e6-a115-18afa1286b06",
      "timestamp": 1234567890,
      "operation": "deletion_in_progress",
      "jobId": "4d2a531a-da2e-47bb-8b9e-ff5adcd53ef0",
      "status": "DELETION_IN_PROGRESS",
      "targetSelection": "SNAPSHOT|CONTINUOUS",
      "targets": [
        "arn:aws:iot:us-east-1:123456789012:thing/Thing0-947b9c0c-ff10-4a80-b4b3-cd33d0145a0f",
        "arn:aws:iot:us-east-1:123456789012:thinggroup/ThingGroup1-95c644d5-1621-41a6-9aa5-ad2de581d18f"
      ],
      "description": "My job description",
      "createdAt": 1234567890123,
      "lastUpdatedAt": 1234567890123,
      "comment": "Comment for this operation"
    }
```

**任务执行最终状态**  
当设备将任务执行更新为终端状态时， AWS IoT 作业服务会发布一条消息：  
+ `$aws/events/jobExecution/jobID/succeeded`
+ `$aws/events/jobExecution/jobID/failed`
+ `$aws/events/jobExecution/jobID/rejected`
+ `$aws/events/jobExecution/jobID/canceled`
+ `$aws/events/jobExecution/jobID/timed_out`
+ `$aws/events/jobExecution/jobID/removed`
+ `$aws/events/jobExecution/jobID/deleted`
消息包含以下示例负载：  

```
{
  "eventType": "JOB_EXECUTION",
  "eventId": "cca89fa5-8a7f-4ced-8c20-5e653afb3572",
  "timestamp": 1234567890,
  "operation": "succeeded|failed|rejected|canceled|removed|timed_out",
  "jobId": "154b39e5-60b0-48a4-9b73-f6f8dd032d27",
  "thingArn": "arn:aws:iot:us-east-1:123456789012:myThing/6d639fbc-8f85-4a90-924d-a2867f8366a7",
  "status": "SUCCEEDED|FAILED|REJECTED|CANCELED|REMOVED|TIMED_OUT",
  "statusDetails": {
    "key": "value"
  }
}
```