---
sidebar_position: 3
sidebar_label: Presence and online
---

# Presence in PHP

Three ways to show people: a presence room lists who is in it to everyone in it (who is in the shop, who is viewing a document). A count says how many, at any size. And who is online is known across your whole app, for a dot on every avatar.

![The browsers of Ann, Ben and Cara, each listing the three of them in the shop now, with their roles from the info of each member](/img/apps/presence-shop.webp)

## A presence room

```php
// Who is in the shop: everyone signed in, with their name and role.
$realtime->room( 'shop', function ( $user ) {
    $person = null === $user ? null : find_user( $user );

    return $person ? [ 'info' => [ 'name' => $person->name, 'role' => $person->role ] ] : false;
}, [ 'presence' => true ] );
```

- **`info`** is what the others see of the member: a name, a role, anything small (up to 4 KB). It is sealed with the room key.
- **`true`** lets them in with your profile ([your users](encryption.md#your-users)).
- **Up to 1,000 members** are listed in full, with `join` and `leave`. Past that, the room counts them, and `members()` pages through them, up to 100,000.

```js
const shop = rt.join( 'shop' );
const draw = () => list( [ ...shop.members ] );        // [ [ id, info ], … ]
shop.on( 'joined', draw );                             // the members as the page joins
shop.on( 'join', ( { id, info } ) => draw() );
shop.on( 'leave', ( { id } ) => draw() );
```

A user is a member once, however many tabs and devices they have in the room, and leaves when the last one does.

## Counting

`[ 'count' => true ]` gives a room a live count, without a list:

```php
$realtime->room( 'product:{id}', null, [ 'public' => true, 'count' => true ] );
```

```js
const product = rt.join( 'product:7' );
product.on( 'count', ( n ) => showLooking( n ) );   // at most once a second
```

A presence room counts too.

## Who is online, across your app

Every page whose user your server vouched for makes that user online. They go offline 10 seconds after their last page closes, so a reload does not flicker.

```js
rt.online.watch( [ 34, 43 ] ).on( 'change', ( { id, online, at } ) => dot( id, online ) );
rt.online.has( 34 );          // true or false, for a user watched
rt.online.lastSeen( 43 );     // when, in ms, for one offline
rt.online.on( 'count', ( n ) => showOnline( n ) );
```

- **A page watches** up to 1,000 users, and gets their status now and every change.
- **Your server asks too:** `$realtime->online()->has( 42 )`, `->count()`, `->list()`.
- **Hiding:** a user who chose not to show their status is never online to anyone:

```php
$realtime = Realtime::fromEnvironment( [
    // …
    'hidden' => fn ( $user ) => (bool) find_user( $user )?->hide_status,
] );
```

## Ready-made: who is online

The Better Messages list of members, on a presence room, with a call button for each of the others. It is one element:

```html
<wordplus-online room="shop" title="In the shop now" call="support:{pair}" type="video"></wordplus-online>
<wordplus-online-count room="product:7"></wordplus-online-count>
```

```js
await rt.callScreen();   // loads the elements and the call screen, rt.ui() the elements without calls
```

- **`call`** names the call the button of each row places: `{pair}` is the two user ids in order (`support:34:42`), `{me}` and `{id}` each one. Without it, the rows have no button.
- **Names and pictures** come from the member info, then from your [directory](encryption.md#your-users).
- **Its look** is that of Better Messages, in a shadow root: your styles do not reach in, and its colours are CSS custom properties your page sets.

More, with Node and Python side by side: [presence in depth](../apps/presence.md).