# Events & Webhooks

Lingk moves your periodic, scheduled integration processes to data-driven events that fit into your business process. Lingk's Event Broker connects real-time data and events with monitoring, analysis, communication, and learning systems.

Here are a few scenarios:

* A Lingk real-time recipe is triggered based on a learning event consumed by another HTTP endpoint.
* As files are transformed, an error occurs due to a schema change in the file. In real-time, a specific event that is subscribed to by a email notification engine and the bug tracking system is created.
* As education data is transformed by the Transformer Engine, events are added to queues for grading, retention, and alerting purposes.

To see an example Node.js project go to: <https://github.com/lingkio/event-triggered-recipe-nodejs>

## **Create a subscription**

```
curl -X POST  
-H "date: Wed, 27 Jul 2016 02:38:11 UTC"  
-H 'Authorization: Signature keyId="asfsdfaf",algorithm="hmac-sha1",headers="date (request-target)",signature="WCIW%2F%2B0WG8tIvpQ0W7t34kksj5Q%3D"' 
-d @subscription.json
https://www.lingkapis.com/v1/@self/webhooks/subscriptions

{
 "tenantKeyFilter": "lingkuni",
 "appKeyFilter": "peoplesoftsis",
 "objectTypeFilter": "*",
 "verbFilter": "*",
 "deliveryUrl": "http://some.lingkto.com/test/webhookdelivery"
}
```

## **Delete a subscription**

```
curl -X DELETE  
-H "date: Wed, 27 Jul 2016 02:39:44 UTC"  
-H 'Authorization: Signature keyId="dfsadfasf",algorithm="hmac-sha1",headers="date (request-target)",signature="wBRwzLuW%2BCXblCFEJtjO9YSjXgw%3D"' 
https://www.lingkapis.com/v1/@self/webhooks/subscriptions/e029485bf8ba4c6ba11b2a62ec208af7
```

## **Get subscriptions**

```
curl -X GET  
-H "date: Wed, 27 Jul 2016 02:41:42 UTC"  
-H 'Authorization: Signature keyId="dfsadfasf",algorithm="hmac-sha1",headers="date (request-target)",signature="oDEh0diKNuzzHSBYXW3tAVywd0g%3D"' 
https://www.lingkapis.com/v1/@self/webhooks/subscriptions
```

## **Post an event**

```
curl -X POST  
-H "date: Wed, 27 Jul 2016 02:43:21 UTC"  
-H 'Authorization: Signature keyId="dfsadfasf",algorithm="hmac-sha1",headers="date (request-target)",signature="V3dgtmkNLvxq7QNPx4kXcSuFU0k%3D"' 
-d @event.json https://www.lingkapis.com/v1/@self/events

 {
    "verb":"create",
    "objectType":"fileUpload",
    "eventObject": { "file":
      { "path": "/path.zip" } 
    }
}

 {
    "verb":"add",
    "objectType":"learningEvent",
    "eventObject": { 
    ... Capliper/xAPI statement ...
    }
}
```

## **Consume Events via a Webhook**

After an event is triggered through the Event Broker, all subscribed endpoints are *pushed* a JSON payload for the event.

The eventObject property contains the data associated with the event. Lingk has a specific eventObject format for files imported into a Data Repository.

Example Webhook Payload

```
{
  "appKey": "courserosters",
  "eventGuid": "538c8a6e2e44477a84e85dbeb921bef9",
  "eventObject": {
    "course": {
      "courseCode": "24617.1101"
    }
  },
  "objectType": "integration.courserosters.testevent",
  "tenantKey": "integration",
  "timestamp": "2016-10-21T06:11:40.267817769Z",
  "verb": "finish"
}
```


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