Question 1

How do I use Primus with Express?

Accepted Answer

Primus attaches to an HTTP server, so you can pass your Express instance as the server parameter. The README shows an example with http.createServer, and the FAQ confirms compatibility by detailing middleware integration.

Question 2

Primus vs Socket.IO: which is better for real-time apps?

Accepted Answer

Primus is ideal if you need to switch between frameworks or avoid lock-in, while Socket.IO offers a more integrated solution with built-in features like rooms. Primus abstracts multiple engines, but Socket.IO might be simpler for projects sticking to one framework.

Question 3

Can I send custom headers with Primus connections?

Accepted Answer

Not directly for all transports, as noted in the README: some transformers like JSONP don't support custom headers. Instead, use query strings for custom data during connection setup.

Question 4

How to scale Primus applications?

Accepted Answer

The README FAQ suggests using load balancers and ensuring sticky sessions, as Primus relies on the underlying framework's scaling mechanisms. You'll need to configure your reverse proxy accordingly for WebSocket support.

Question 5

What's the best way to handle authentication in Primus?

Accepted Answer

Use the built-in authorization hook with primus.authorize, which validates connections before they're established. The README provides examples using basic-auth-parser and error handling for different HTTP status codes.

Question 6

How to add custom middleware in Primus?

Accepted Answer

Use primus.use to add middleware layers that intercept HTTP and upgrade requests. The README details sync and async middleware, including how to disable them for specific request types like upgrades.

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