---
sidebar_position: 7
sidebar_label: Live streams
---

# Live streams in Express

One person presents live to everyone watching: the picture, a chat beside it, reactions, and the count of who watches. The host goes live from the browser, a phone or OBS. Viewers may be signed in or not.

## Who is who

Your server declares streams as it declares rooms and calls, by pattern. The rule says who each person is in the stream:

```js
// The show of the shop, show:mugs: Ann presents it, and everyone else watches and writes in its chat, signed in or not.
realtime.streams( 'show:{id}', ( user, { id } ) => {
    if ( id !== 'mugs' ) return false;
    return user === ANN ? 'host' : 'viewer';
}, { reactions: true } );
```

- **The answer:** `false`, `'host'` or `'viewer'`, or `{ role, info, chat, mod, src, quality }` for more: what others see of them, whether they write in the chat (`write` or `read`), whether they keep it, and what the host sends.
- **A visitor who is not signed in** comes with `user` null, and may only be a viewer.
- **The settings of the stream**, the third argument: `reactions`, `people` and `chat: { offline, links, fresh }` ([live streams in depth](../apps/streams.md#who-is-who)).

The calls route (`/api/realtime/calls`) answers streams too: nothing more to add to `realtime.node()`.

## The page

```js
const calls = await rt.calls();
const show = await calls.stream( 'show:mugs' );

show.watch( document.querySelector( '#show video' ) );      // the picture and its sound
show.on( 'state', ( state ) => draw( state ) );            // idle, live, ended
show.on( 'viewers', ( n ) => ( count.textContent = `${ n } watching` ) );
show.on( 'message', ( m ) => addLine( m.from.name, m.text ) );
await show.chat.send( 'Hello!' );
```

The page of the host goes live with the camera and ends it:

```js
if ( show.role === 'host' ) {
    await show.preview();    // the camera, shown in the same video
    await show.goLive();
    // …
    await show.end();
}
```

The show card of the Example Shop does exactly this, in `showCard()` of `examples/shop/shop.js`.

## More

Reactions, keeping the chat, OBS, and the refusals: [live streams in depth](../apps/streams.md).