WSProxy

Websockets proxy server written in Haskell.

Designed to be run as a standalone server for peculiar use-cases. It was built to serve as a proxy between Heroku server and browser. Since Heroku uses a random load-balancer, it becomes impossible to establish websocket connections between client and Heroku app with >1 servers. Drop this proxy in the middle and it will translate websocket requests to HTTP.

Setup

For most use cases, it may be sufficient to run wsproxy on a single-dyno Heroku instance. Like so:

git clone https://github.com/nathankot/wsproxy
cd wsproxy
heroku create --stack=cedar --buildpack https://github.com/begriffs/heroku-buildpack-ghc.git
git push heroku master

Configuration

All configuration is done via ENV variables. There is no need to modify the source code to use this.

Variable	Description	Default
PORT	HTTP port to listen on	`3636`
SERVER	Server to upstream websocket messages to	`""`

Connecting to wsproxy

Connections are opened by sending a message in the form of Connect:<identity>.

var ws = new WebSocket("wss://wsproxy.server.com");

ws.onopen = function() {
  var iden = 'username'; // This is the identifier, it can be anything
  ws.send('Connect:' + iden);
}

ws.onmessage = function(o) {
  var msg = o.data;
  if (msg === 'Connection acknowledged') {
    console.log('Websockets connection established');
  }
}

Sending messages downstream

HTTP requests against wsproxy get translated to websocket messages. Requests should look like this:

POST https://wsproxy.server.com/push?identity=username&message=new%3Aitem

All clients with identities of username will now get a websockets message new:item

Sending messages upstream

Websocket messages toward wsproxy get translated into HTTP requests if SERVER is defined. A message sent like so:

ws.send("Any message");

Will be translated to an HTTP requests against SERVER like so:

POST https://api.server.com/any/api/endpoint?identity=username&message=Any%20message

License

The MIT License (MIT)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.