The Brave New World of Server-Side Javascript
Not the B Team
Every once in a while I hear whispers of server-side javascript and I get just as excited as the next person. But, I’ll admit that until recently a phrase like “Javascript on Rails” was on the same level as a phrase like “McGyver vs. The A Team – The Movie.” Fictonal. But awesome in theory.
(Don’t worry, they eventually join forces in the sequel)
But what about Jaxer?
My limited experience with server-side javascript (SSJ) has been through Jaxer, from Aptana. It touts some cool functionality, like loading the DOM server-side and built-in database drivers for MySQL, with the former allowing for DOM manipulation and integration with libraries like jQuery.
Ubiquitous "Gear" Logo
But, in its attempts to blur the lines between client and server execution, Jaxer has made sacrifices in its extensibility. It is meant to be plugged into another system. For instance, I don’t know of an easy way to expose data through a RESTful JSON/XML API (like so many sites are doing nowadays) using Jaxer alone.
What I’m really looking for in SSJ is something akin to the ecosystem surrounding languages like Ruby and Python. That’s why I was pleasantly surprised to stumble accross a few projects that aim to do just that.
Narwhal – Javascript Standard Library and Interactive Console
The foundation of any good ecosystem is a standard library. Enter Narwhal, “a flexible javascript standard library.”
There are a lot of things to like about this project, but the primary benefit is its attempts to play nice with multiple javascript runtimes like Rhino and V8cgi. Also, this project is embracing Mozilla’s ServerJS standard which I think is important for its longevity and interoperability.
Setup is a breeze, you can simply clone the project from github:
git clone git://github.com/tlrobinson/narwhal.git
Once you add narwhal/bin to your $PATH, you can use the convenient symlink js to enter an interactive javascript console similar to irb or python.
Jack – Javascript’s “Rack”
Interestingly enough, Narwhal came into existence as it’s author, Tom Robinson, was working on Jack.
JSGI is a webserver interface for JavaScript inspired by Ruby’s Rack (http://rack.rubyforge.org/) and Python’s WSGI (http://www.wsgi.org/).
Jack is an implementation of JSGI compatible handlers (to connect to web servers), middleware (to intercept and manipulate requests to add functionality), and utilities (to make using JSGI easier).
Setup is also breezy. Simply clone Jack into the same directory you cloned Narwhal into:
git clone git://github.com/tlrobinson/jack.git
Since you’ve already added narwhal’s bin directory to your path, lets just make a symlink to jackup from there.
From your narwhal/bin directory:
ln -s [path/to/jack]/bin/jackup jackup
Run jackup -h for usage.
So, what’s next? Where’s Javascript on Rails?
With Narwhal and Jack, you can start writing basic web apps. Looking at the example.js script in jack/examples we can see the basic request/response structure. Looks familiar huh?
var Jack = require("jack");
var map = {};
// an extremely simple Jack application
map["/hello"] = function(env) {
return [200, {"Content-Type":"text/plain"}, ["Hello from " + env["SCRIPT_NAME"]]];
}
// apply the URLMap
var app = Jack.ContentLength(Jack.URLMap(map));
//...
While these two pieces are a good start to a vibrant server-side javascript ecosystem, there’s still a long ways to go to before it’ll be on par with Ruby and Python.
What SSJ needs is its Django/Pylons/Rails/Merb. There are a couple of projects I’ve found in the wild that are using Jack and Narwhal, but they appear to still be in very rapid flux.
Nitro provides a library of carefully designed middleware and utilities for creating scalable, standards-compliant Web Applications with JavaScript.
Helma NG consists of several components that can be used together or alone:
1) A compact JavaScript runtime environment based on Mozilla Rhino. It adds
to Rhino a reloading module system that is compatible to the ServerJS
Securable Module proposal.2) An interactive shell with support for autocompletion and history.
3) A module library implemented in JavaScript, covering basic functionality
such as extensions to the built-in objects, file I/O, logging, persistence,
client and server side HTTP support and more.