Flutter WebSockets connect to Socket.io Server

Question

I have built a socket.io server using Node.js and Express. All works fine from browser and normal socket.io client but when I try to use WebSocket in Flutter I get the error

HttpException: Connection closed before full header was received, uri = http://csw.abbadabba.tech:3001

I am just trying to get it to work with a basic connect like this:

var _url = 'ws://csw.abbadabba.tech:3001';
WebSocket chatsocket = await WebSocket.connect(_url);
chatsocket.add('connect');

Looking for anyone who has done this already and has some samples to look at, trying to have a chat server that my app is always connected to, so if there is a better server architecture to use I am open to that as well. Any help would be great.

Thanks in advance.

Answer 1

The problem is that you are trying to use Flutter's WebSocket implementation to connect to a socket.io server. Although socket.io does use WebSockets, it is NOT a pure web socket implementation and isn't recognized by default WebSocket client as valid. You'll need to use a specific socket.io flutter package.

From the socket.io documentation: https://socket.io/docs/#What-Socket-IO-is-not

What socket.io is not

Socket.IO is NOT a WebSocket implementation. Although Socket.IO indeed uses WebSocket as a transport when possible, it adds some metadata to each packet: the packet type, the namespace and the ack id when a message acknowledgement is needed. That is why a WebSocket client will not be able to successfully connect to a Socket.IO server, and a Socket.IO client will not be able to connect to a WebSocket server either.

Answer 2

adhara_socket_io

dependencies:
adhara_socket_io: ^0.1.11

This is good implementation of socket.io for flutter ->