Skip to main content
The REST API supports Server-Sent Events (SSE) for real-time streaming. Send a GET request with Accept: text/event-stream and Lark pushes data changes to you as they happen.

​
Starting a stream

curl -N \
  -H 'Accept: text/event-stream' \
  'https://chess-app.larkdb.net/my-game/players.json?auth=YOUR_TOKEN'
The -N flag disables curl’s output buffering so events appear immediately.

​
Event format

Events follow the SSE specification. Each event has a type and a JSON data payload: 
event: put
data: {"path":"/","data":{"alice":{"name":"Alice","score":250},"bob":{"name":"Bob","score":180}}}

event: patch
data: {"path":"/alice/score","data":300}

event: put
data: {"path":"/carol","data":{"name":"Carol","score":0}}

​
Event types

EventDescription
putData at the path was replaced. The initial event is always a put with the full value at the subscribed path.
patchData was partially updated. Only the changed fields are included.
keep-aliveSent periodically to keep the connection open. No data payload.
cancelThe stream was terminated — typically because security rules revoked read access.
auth_revokedThe auth token expired or was invalidated.

​
Initial data

The first event on any stream is a put containing the complete current value at the path: 
event: put
data: {"path":"/","data":{"alice":{"name":"Alice","score":250},"bob":{"name":"Bob","score":180}}}
After that, you receive incremental put and patch events as data changes.

​
Path semantics

The path field in each event is relative to the path you subscribed to. If you stream /players:
  • {"path":"/","data":{...}} — The entire /players subtree changed.
  • {"path":"/alice/score","data":300} — Only /players/alice/score changed.
  • {"path":"/carol","data":{"name":"Carol","score":0}} — A new child /players/carol was added.

​
Using SSE in code

​
Browser (EventSource)

const url = 'https://chess-app.larkdb.net/my-game/players.json?auth=YOUR_TOKEN';
const source = new EventSource(url);

source.addEventListener('put', (e) => {
  const { path, data } = JSON.parse(e.data);
  console.log('PUT at', path, data);
});

source.addEventListener('patch', (e) => {
  const { path, data } = JSON.parse(e.data);
  console.log('PATCH at', path, data);
});

source.addEventListener('cancel', () => {
  console.log('Stream cancelled — check security rules');
  source.close();
});

​
Node.js

Use any SSE client library, or read the stream manually: 
const response = await fetch(
  'https://chess-app.larkdb.net/my-game/players.json?auth=YOUR_TOKEN',
  { headers: { 'Accept': 'text/event-stream' } }
);

const reader = response.body!.getReader();
const decoder = new TextDecoder();

while (true) {
  const { done, value } = await reader.read();
  if (done) break;

  const text = decoder.decode(value);
  // Parse SSE events from text
  console.log(text);
}

​
When to use streaming

SSE streaming is useful when you need real-time updates but can’t use a WebSocket-based SDK:
  • Server-side listeners — Watch for changes from a backend service.
  • Monitoring and logging — Stream events to a log pipeline.
  • Simple web clients — EventSource is built into every browser with no dependencies.
For most client-side applications, the Lark SDK or Firebase SDKs provide a better developer experience with automatic reconnection, local caching, and typed snapshots.