# APIv3: Socket.IO alarm channel
### Complete sample client code
```html
APIv3 Socket.IO sample for alarms
```
### Subscription (authorization)
The client must first subscribe to the channel that is exposed at `alarm` namespace, ie the `/alarm` subadress of the base Nightscout's web address (without `/api/v3` subaddress).
```javascript
const socket = io('https://nsapiv3.herokuapp.com/alarm');
```
Subscription is requested by emitting `subscribe` event to the server, while including document with parameter:
* `accessToken`: required valid accessToken of the security subject, which has been prepared in *Admin Tools* of Nightscout.
```javascript
socket.on('connect', function () {
socket.emit('subscribe', {
accessToken: 'testadmin-ad3b1f9d7b3f59d5'
}, ...
```
On the server, the subject is identified and authenticated (by the accessToken). Ne special rights are required.
If the authentication was successful `success` = `true` is set in the response object and the field `message` contains a text response.
In other case `success` = `false` is set in the response object and the field `message` contains an error message.
```javascript
function (data) {
if (data.success) {
console.log('subscribed for alarms', data.message);
}
else {
console.error(data.message);
}
});
});
```
### Acking alarms and announcements
If the client is successfully subscribed it can ack alarms and announcements by emitting `ack` message.
```javascript
socket.emit('ack', level, group, silenceTimeInMilliseconds);
```
where `level` and `group` are values from alarm being acked and `silenceTimeInMilliseconds` is duration. During this time alarms of the same type are not emmited.
### Receiving events
After the successful subscription the client can start listening to `announcement`, `alarm` , `urgent_alarm` and/or `clear_alarm` events of the socket.
##### announcement
The received object contains similiar json:
```javascript
{
"level":0,
"title":"Announcement",
"message":"test",
"plugin":{"name":"treatmentnotify","label":"Treatment Notifications","pluginType":"notification","enabled":true},
"group":"Announcement",
"isAnnouncement":true,
"key":"9ac46ad9a1dcda79dd87dae418fce0e7955c68da"
}
```
##### alarm, urgent_alarm
The received object contains similiar json:
```javascript
{
"level":1,
"title":"Warning HIGH",
"message":"BG Now: 5 -0.2 → mmol\/L\nRaw BG: 4.8 mmol\/L Čistý\nBG 15m: 4.8 mmol\/L\nIOB: -0.02U\nCOB: 0g",
"eventName":"high",
"plugin":{"name":"simplealarms","label":"Simple Alarms","pluginType":"notification","enabled":true},
"pushoverSound":"climb",
"debug":{"lastSGV":5,"thresholds":{"bgHigh":180,"bgTargetTop":75,"bgTargetBottom":72,"bgLow":70}},
"group":"default",
"key":"simplealarms_1"
}
```
##### clear_alarm
The received object contains similiar json:
```javascript
{
"clear":true,
"title":"All Clear",
"message":"default - Urgent was ack'd",
"group":"default"
}
```