WebSockets
the UNIX way

Full duplex messaging between web browsers and servers

websocketd is the WebSocket daemon

It takes care of handling the WebSocket connections,
launching your programs to handle the WebSockets,
and passing messages between programs and web-browser.

It's like CGI, twenty years later, for WebSockets

Built for the UNIX philosophy

Write programs that do one thing and do it well.
Write programs to work together.
Write programs to handle text streams,
because that is a universal interface.

If you dig that, you'll dig websocketd.

10 second tutorial

Let's create a tiny WebSocket server that counts to ten, pausing between each iteration.

Create a program in your favorite language:

#!/bin/bash

# Count from 1 to 10 with a sleep
for ((COUNT = 1; COUNT <= 10; COUNT++)); do
  echo $COUNT
  sleep 0.5
done

  
     String  args  Exception 
      i i i 
      Systemouti
      Thread
    
  

 sys  stdout
 time  sleep

 count  range 
  count  
  stdoutflush
  sleep

sync  
  count
	puts count
	

#usrbinperl
use TimeHiRes sleep
# Autoflush
$
# Count from  to  with a sleep
 my $count    
	print 
	sleep 

  
     i

    
    stdout NULL

     i   i   i 
         i
        
    

     

 System
 SystemThreading

 

    
  
      i   i   i
    
      Consolei
      Thread
    
  

#usrbinenv xcrun swift
 

 index   
  index
  __stdoutp
  

import 

 
    i   i   i 
    i
     milliseconds 
  

You get the idea

If you can  a program that can be launched from
the  line you can build a WebSocket server

Read inbound messages from STDIN
Write outbound messages to STDOUT

Read HTTP and connection details from environment vars
Use line breaks as message delimiters

Start websocketd and tell it about your program:

$ websocketd --port=8080 my-program

Now connect to your program from JavaScript in a web-page using a WebSocket:

var ws = new WebSocket('ws://localhost:8080/');

ws.onmessage = function(event) {
  console.log('Count is: ' + event.data);
};

See... WebSocket servers are simple!

Whichever way inclined you are

I Groovy

• Python
• JavaScript
• Clojure
• Scala
• Groovy
• VB.Net
• Swift
• Objective-C
• VBScript
• Expect
• AppleScript
• Haskell
• Pascal
• Assembly
• Fortran
• Ocaml

Oh, and...

Static server

Serves your static HTML, JavaScript, etc

Program routing

Route different URLs to different programs

CGI server

Dynamic generate content over HTTP too

Out-of-the-box support for serving content using HTTPS and WSS

Origin checking

Restrict which pages can make WebSocket connections

Development console

Interact with your WebSocket programs before you've built your frontend

Announcements, new features, security advisories

We won't share your email address with anyone else. Pinky swear.

Created by Joe Walnes - Project lead: Alex Sergeyev

Written in Go - Forky forky on GitHub