Pusher and WebSockets are both used for real-time communication between a server and a client, but they have some differences in terms of implementation and functionality.

WebSockets is a protocol that enables bidirectional communication between a client and a server over a single, long-lived TCP connection. With WebSockets, a client can send a request to the server and keep the connection open to receive multiple responses, without having to repeatedly establish a new connection. This makes WebSockets ideal for applications that require low latency and real-time communication, such as chat apps and online games.

Pusher, on the other hand, is a cloud-based service that provides real-time communication capabilities to web and mobile applications. It uses WebSockets as its underlying transport protocol, but abstracts away much of the low-level implementation details, making it easier to integrate real-time features into your application. Pusher provides a number of additional features beyond what WebSockets alone can offer, such as presence detection, channel authentication, and serverless functions.

Another difference between Pusher and WebSockets is that Pusher is a managed service, meaning that the infrastructure and maintenance of the service is handled by Pusher, while with WebSockets, you need to set up and maintain your own WebSocket server.

In summary, WebSockets is a protocol that allows for real-time, bidirectional communication between a client and a server, while Pusher is a managed service that provides additional features on top of WebSockets, such as presence detection and channel authentication, making it easier to integrate real-time features into your application.

A side topic to know: Presence detection

Presence detection is a feature provided by some real-time communication platforms, including Pusher, that allows you to track the online status of users in real-time. It lets you know when users join or leave a channel, as well as their current state, such as whether they are currently active or idle.

With presence detection, you can build real-time applications that react to changes in user presence, such as updating a user’s status on a chat app when they go offline or showing which users are currently active in a multiplayer game.

Presence detection is typically implemented using a combination of client-side and server-side code. The client-side code sends a message to the server when a user joins or leaves a channel, and the server updates the presence information for that user. Other clients can then subscribe to this presence information and receive real-time updates as users join or leave the channel.

Pusher provides a Presence Channels feature that makes it easy to implement presence detection in your application. It provides a set of server-side APIs for managing presence information and a client-side library for subscribing to presence events.