what are EIO=3&transport=websocket in websocket url

Question

wss://www.mysite.ca/socket.io/?EIO=3&transport=websocket

This is how chrome webdevoloper tools shows the request url of a socket io.

I am trying to understand more about EIO=3&transport=websocket .

I have to invoke the url from an API tool

Answer 1

These are query parameters that the socket.io client sends to the socket.io server as part of the initial connection request.

EIO=3, I believe, is the version number of the engine.io sub-system in socket.io. If the server is not compatible with this version number, it will likely fail the attempt to connect.

transport=websocket says that socket.io wants to use the websocket protocol as the eventual transport. socket.io has several different transports it supports including web polling and a flash-based protocol.

To connect to socket.io server, you will need a full-fledged socket.io client. You can't make a socket.io connection by just sending a URL from a tool to the server. There's a lot more involved than that in establishing a working socket.io connection.