Glossary

Short definitions for the terms that show up across the rest of the site. Each entry is one page. Each page links to the related entries and to the compare, migrate, or learn pages where the term shows up in context.

Terms

• Broadcast is the single message a publisher sends to a channel, distinct from the per-subscriber copies that get delivered.
• Channel auth is the signed handshake that authorizes a client to subscribe to a private or presence channel.
• Concurrent connections is the count of WebSockets currently open against a real-time service, and the gauge that sets pricing tier.
• Fan-out is the mechanism by which one broadcast on a channel is delivered to every subscriber of that channel.
• Fan-out tax is the per-delivered-copy surcharge some real-time services attach to broadcasts.
• Presence channel is a channel type that maintains a server-side member roster and emits join and leave events.
• Private channel is a channel type that requires a server-side auth callback before a client may subscribe.
• Public channel is a channel type that any connected client can subscribe to without auth.
• Pusher protocol is the open WebSocket protocol for channel subscriptions, named events, and auth.
• WebSocket is the persistent, bidirectional connection between a client and a server that real-time protocols run on top of.