connection.socket.on('open') doesn't work

[Gianthard-cyh]

Prerequisites

• [X] I have written a descriptive issue title
• [X] I have searched existing issues to ensure the bug has not already been reported

Fastify version

4.10.0

Plugin version

7.1.1

Node.js version

19.1.0

Operating system

Linux

Operating system version (i.e. 20.04, 11.3, 10)

ubuntu 20.04

Description

test.js

const fastify = require('fastify')({ logger: false })
fastify.register(require('@fastify/websocket'))
fastify.register(async function (fastify) {
  fastify.get('/', { websocket: true }, (connection /* SocketStream */, req /* FastifyRequest */) => {
    connection.socket.on('open', () => {
      console.log('connected')
    })
    connection.socket.on('message', () => {
      console.log('message')
    })
    connection.socket.on('close', () => {
      console.log('close')
    })
  })
})

fastify.listen({ port: 3035, host: '0.0.0.0' }, err => {
  if (err) {
    fastify.log.error(err)
    process.exit(1)
  }
})

I've tried postman and my browser to create ws connection but none works. message and close events are properly handled, but open is not.

Steps to Reproduce

const fastify = require('fastify')({ logger: false })
fastify.register(require('@fastify/websocket'))
fastify.register(async function (fastify) {
  fastify.get('/', { websocket: true }, (connection /* SocketStream */, req /* FastifyRequest */) => {
    connection.socket.on('open', () => {
      console.log('connected')
    })
    connection.socket.on('message', () => {
      console.log('message')
    })
    connection.socket.on('close', () => {
      console.log('close')
    })
  })
})

fastify.listen({ port: 3035, host: '0.0.0.0' }, err => {
  if (err) {
    fastify.log.error(err)
    process.exit(1)
  }
})

Expected Behavior

No response

[jsumners]

The docs https://github.com/fastify/fastify-websocket/blob/1e41ac4aa3ce21a69e6718977509fee8c5d0f22e/README.md do not mention an open event. They only mention a message event.

[Gianthard-cyh]

The docs https://github.com/fastify/fastify-websocket/blob/1e41ac4aa3ce21a69e6718977509fee8c5d0f22e/README.md do not mention an open event. They only mention a message event.

so how can i do if i want to send a message immediately after the connection is open?

[airhorns]

You can just send right in the request handler!

fastify.get('/', { websocket: true }, (connection /* SocketStream */, req /* FastifyRequest */) => {
    connection.socket.send("synchronous message on connection open")
  })

[climba03003]

When you reach the handler, it is already open. @fastify/websocket is server side, once it reach. It means the connection already there.