socket.io cannot communicate with back-end through express - node.js

Question

I am using socket.io for fetching some data from the express app. Everything works fine on localhost:8080 but when i deploy my code to the server, client side socket.io cannot communicate with back-end socket.io through express server. I've an apache on the server that forwards everything to localhost:8080 including domain.com/socket.io/?transform=polling... and it extends the request to the express server but express returns a 404 (it comes from the express, not from apache). I am out of ideas, what could be the problem? Here is my code:
express = require "express"
jade = require "jade"
fs = require "fs"
class Bootstrap
_self = undefined
routes:
DEFAULT_PATH: "/"
TEMPLATE_PATH: "/load/:view"
DIRECTIVE_PATH: "/directive/:template"
options:
templatePath: "#{__dirname}/../src/templates"
isDev: "#{__dirname}/../dev"
contentPath: "#{__dirname}/../frontend"
libraryPath: "#{__dirname}/../bower_components"
port: 8080
status:
notFound: 404
isDev: undefined
constructor: ->
_self = #
#isDev = fs.existsSync #options.isDev
#app = express()
#app.use "/frontend", express.static(#options.contentPath)
#app.use "/bower_components", express.static(#options.libraryPath)
#app.set "views", #options.templatePath
#app.set "view engine", "jade"
#app.engine "jade", jade.__express
#app.get #routes.DEFAULT_PATH, (request, response)->
appData =
data:
isDev: _self.isDev
response.render "index", appData
#app.get #routes.TEMPLATE_PATH, (request, response)->
view = request.param "view"
response.render view
#app.get #routes.DIRECTIVE_PATH, (request, response)->
template = request.param("template").replace ".html", ""
response.render "directives/"+template
#app.use (request, response, next)->
_self.logger.warning "404 Not Found!: " + request.originalUrl
response.status(_self.options.status.notFound)
appData =
data:
isDev : _self.isDev
request: request
response.render "404", appData
#server = #app.listen #options.port
#io = require("socket.io").listen #server
#logger = require("./logger.js")
#logger.init #isDev
#socketConnector = require("./live.js")
#socketConnector.init #io
#
new Bootstrap()
You can find the entire code here: https://github.com/eyurdakul/ejder.be

Answer 1

Since you specifically said it works locally and I don't see anything special in your code, I really think the issue resides in your Apache config.
There is a module called mod_proxy_wstunnel you need to have and enable in order to get your WebSocket traffic to work and get proxied correctly to your express application. Either you have Apache 2.4 or, you'll need to apply this patch found in this blogpost and compile again. There is also another blog detailing step by step what you should do under Ubuntu.
After making sure you have the module and its loaded, you'll have to tweak your config to add some WebSocket proxying using the ProxyPass directive
ProxyRequests Off
ProxyPass "/socket-io/" "ws://localhost:8080/socket.io/"
ProxyPassReverse "/socket-io/" "ws://localhost:8080/socket.io/"
You might also want to try to use a rewrite condition on the Upgrade header that is sent with WebSockets:
RewriteEngine On
RewriteCond %{HTTP:Connection} Upgrade [NC]
RewriteRule /(.*) ws://localhost:8000/$1 [P,L]
ProxyPass / http://localhost:8000/
has seen in this comment or this specific thread in general, which exposes a few other possible solutions you can try.

Answer 2

A debugging step that you should take is to have a mock client run in your express app and try to connect to the server port using localhost, or whatever the loopback IP address is. In other words (purely as a temporary testing tool) you place a socket.io Node client into your Express app that gets instantiated and immediately tries to connect to the Socket.io server (which is also in the express app). This should work.
If it does work, you've established that your express server is not the problem. Then, on the client you just added to your express app, you should change the connection address from the local IP to the actual IP address of the server.
If it doesn't work, your problem is probably server side.
My guess is that your apache server is forwarding the polling requests properly, but when Socket.io tries to make the handoff to websockets, Apache is denying the WS request and socket.io is handling this denial internally -- which is why the 404 seems to come from express.

Answer 3

Even I had same issue. The port on which the server is listening , is that open on server. As on local all the ports are open but on server , it's not the case.