# WebSocket
Tvheadend has a WebSocket interface on port 9981. It is used by the UI to provide 'live' actions and updates, avoiding the need to refresh the screen.
### Example Code
The example below creates a WebSocket connection to the Tvheadend server and listens for updates.
```
Websocket Test
```
### Output
Tvheadend transmits messages on the Websocket interface asynchronously, when either an event occurs or in some cases at scheduled intervals. The output format is JSON.
Each message contains a key "messages" whose value is an array of message objects. Each message object contains a key "notificationClass" which specifies the source of the message, and a series of message-specific key-value pairs.
```
{
"messages": [
{
"freediskspace": 607828439040,
"useddiskspace": 135628398200,
"totaldiskspace": 861450428416,
"notificationClass": "diskspaceUpdate"
},
{
"notificationClass": "logmessage",
"logtxt": "2024-03-06 11:06:14.444 subscription: 00D5: \"HTTP\" subscribing on channel \"DMAX\", weight: 100, adapter: \"DVB-T #0\", network: \"Sandy\", mux: \"690MHz\", service: \"DMAX\", profile=\"pass\", hostname=\"192.168.1.2\", client=\"VLC/3.0.20 LibVLC/3.0.20\""
},
{
"id": 213,
"start": 1709723174,
"errors": 0,
"state": "Running",
"hostname": "192.168.1.2",
"client": "VLC/3.0.20 LibVLC/3.0.20",
"title": "HTTP",
"channel": "DMAX",
"service": "DVB-T #0/Sandy/690MHz/DMAX",
"pids": [
1011,
2401,
2402,
2403,
2404
],
"profile": "pass",
"in": 57716,
"out": 57716,
"total_in": 57716,
"total_out": 57716,
"updateEntry": 1,
"notificationClass": "subscriptions"
}
]
}
```
### Object Changes
Some "notificationClass" messages may optionally contain one or more of the following arrays: "create", "change" and "delete". When present, these arrays will contain lists of UUIDs that have been created, modified or deleted as part of the scope of the current notification.
```
{
'messages': [{
'change': [
'3b0c29363b43ebd73f37c54dc18d2b0e',
'9651da654aa7d2f620946fcbae7500a6'
],
'notificationClass': 'channel'
}
]
}
```
When a "notificationClass" is "epg", the arrays described above will contain EventIds rather than UUIDs and the 'update" array will be present rather than "change". Two additional arrays ('dvr\_delete' and 'dvr\_update') may also be present to indicate a change in recording status of the EPG event.
With regards to "create" and "change"/"update" notifications, the UUID/EventID will need to be explicitly fetched to obtain the new object property values.
---
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```
GET https://docs.tvheadend.org/documentation/development/json-api/websocket.md?ask=
```
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