Channels

Channels are the core primitive for organizing realtime messages. Every event is published to one or more channels.

Public Channels

Any client can subscribe without authentication.

const channel = relay.subscribe('news');
channel.bind('breaking', (data) => console.log(data));

Private Channels

Prefixed with private-. Require server-side authentication before subscribing.

const channel = relay.subscribe('private-user-123');
channel.bind('notification', (data) => console.log(data));

The client automatically calls your auth endpoint (/broadcasting/auth or configured authEndpoint) with the socket_id and channel_name. Your server validates access and returns an HMAC signature.

Presence Channels

Prefixed with presence-. Like private channels, but also track who's online.

const channel = relay.subscribe('presence-room-42');

channel.bind('pusher:subscription_succeeded', (members) => {
    console.log('Online:', members.count);
});

channel.bind('pusher:member_added', (member) => {
    console.log('Joined:', member.id);
});

channel.bind('pusher:member_removed', (member) => {
    console.log('Left:', member.id);
});

Your auth endpoint must return channel_data with user_id and optional user_info:

{
    "auth": "key:signature",
    "channel_data": "{\"user_id\":\"123\",\"user_info\":{\"name\":\"Tom\"}}"
}

Cache Channels

Prefixed with cache-. The server remembers the last event and delivers it immediately when a new client subscribes. Great for showing current state.

const channel = relay.subscribe('cache-stock-prices');
channel.bind('update', (data) => renderPrices(data));

Client Events

Clients can send events directly to other subscribers on private/presence channels. Event names must start with client-.

// On private or presence channels only
channel.trigger('client-typing', { user: 'Tom' });

Channel Naming

• Max 200 characters
• No spaces
• Prefix determines type: private-, presence-, cache-, no-history-
• no-history- prefix disables message history storage