Project Archer – part 1 – concept

Summary:

Creating a close to real-time MMO archer game in Javascript.

((TL;DR jump to Development Plan))

History:

I’m a big fan of game mechanics, everything else may come second, but if the eye-hand challenge don’t feel right, the game most certainly goes down the drain.

The inspiration for this project came about 5 years ago:

Game design

I’ve been thinking of this project since i first shot birds at Bowman 2. The game played under this mode (sandbox) on Android 2, is dead simple. Drag and release to shoot an arrow! Simple but interesting graphic behaviours emerge. Like one arrow hitting 2 or more birds, one arrow that goes up 90 deg, and hit your archer in the head! Maybe go turbo and create an arrow storm!

None of the effects I mentioned give out any score, there is no positive reinforcement mechanism either! It’s plain that screen made for sadistic individuals like myself. And yes, i got tired of it quickly, but still, the mechanics just felt so good for a few minutes.

Add MMO capabilities, a persistent world, one arrow that would teleport my character so now it can move through the scenario, of course some level design.. easy (not easy).

But then I thought, that’s too simple.. I want to embed some great elemental combinations, like Magicka! That would make the game more dynamic and engaging. Of course it would at least double development time, but not a single fuck is given about it in imagination world.

Of course I’m also a big fan of LoL, Kog’Maw being my favourite champion. So i thought i’d embed a somewhat similar cooldown system for each arrow, probably a skill tree would also be in place.

Well then, considering elements I want in the game and overlooking a bit of level design that should be enough to think about.

Enter technical choices.

Question: what free game framework support real time multiplayer, is performant and use pure HTML5? … none.

Partial answer, I love Phaser.io, so easy and fun to develop with. But 2 elements held me back at choosing it right away.

Biggest one was, how to sync multiple players on the same space? After all people should be seeing the same arrow flying and hitting the same stuff. When microseconds matter for accurate shots to happen, sync can’t be taken for granted. In fact there are many techniques online shooting games use that were not available out of the box for browser games. Even Websockets couldn’t support it as it’s based on  TCP, not UDP. WebRTC just came in years later.

So… Unity 3D? 😢

They do pack all i’d need for game design, asset management, physics, and i bet there is much more. There was a cost at the time to deploy at mobiles but it would deliver a much superior performance than something in HTML5.

But 3 factors drove me away:

• vendor locking
• no HTML5 deploy for browsers
• considerable learning curve
• real time networking (MMO) was still crawling

So specially for the networking implementation complexity i gave up on this lib.

I thought another of many other libs that use SVG or WebGL, so we could pack more interesting visual effects, but a decision was never made. Work took a huge space in my life, along with moving to new places and investing in more ‘social time’ something new for the geeky me.

🕛🕝🕞🕘🕙🕚🕐

Development Plan – proof of concept

Present day, present time: 2016-03-08 6PM. In between jobs is probably my most accurate status.

There is no time limit set for this project, nor I consider delivering consistently.

Current goal: rendering something that shoots something, and the scenario should sync for every player connected within 1 second. Ideally, the world state persist.

Pragmatically, the floor will be a flat plain and limited in length. The ‘archer’ spawn at a random position, it represents under control of a player while they are connected. It should be able to shoot a basic physical object, it goes off horizontally at the press of a button – so controls are reaaaally simple.

Architecture lowdown

Clients will run the all of game logic, it should as usual process inputs, events and send (ideally) deterministic information to the server. Almost all input is transmitted, but also the results (where arrow hits, what happened, etc).

The server would be pretty much ignorant of all game logic, not validating inputs / results but storing events and transmitting it to connected clients. When a client come to reconnect the server would send all events.

Needless to say, this is not a secure client-server architecture, it’s much more of a p2p. In traditional multiplayer architecture, the client acts as a vessel for input & rendering, while the server is in charge of processing action, events & results. Our case is simplified as proposed:

• game spawn player 1 at randomly generated X/Y position (send event with position)
• player 1 holds down button to shoot arrow (send event with position)
• player 1 release arrow 1 (send event with angle, force, …)
• arrow 1 hits the floor or enemy and become immovable (send position it hit)

All events should be sync in between clients as they arrive. Still unsure on how to fine sync certain things, like arrow trajectory.. some funky jitter may happen.

Tech choices:

The foundation laid made upon Phaser.io & Firebase for a 1st try.

Using Browserify + npm for managing packages.

Most likely deploying @ Heroku or GitHub Pages.

Unknowns and risks

¿Can firebase add any arbitrary data on server side, when it receives my json Object, and before re-transmitting it? I really need to set a timestamp when an event it arrives.

¿Can I really sync physics in such simplistic way?

¿Will the delay of Firebase events be acceptable? If not i could run some WebRTC solution on the side.

¿Is it going to work on mobile as is?

Wrapping up

Hope to deliver a first version soon, stay tuned!

 

 

JSONP with Express.js API – cross domain request

The problem:

So you have this awesome API endpoint, but of course it is another domain as the static site.

Web browsers are pretty moody with Cross Domain and there are actually very good security reasons for that, but even using good practices the old Internet Explorer don’t care.

Welcome ancient jsonp techniques!

Solution

For some Express.js API running on Node.js and client using jQuery (or something alike)

In your server:

app.get('/my-unique-endpoint', function(req, res, next) {
  var myAwesomeResource = ["hello", "mundo"];
  if (req.query && req.query.callback) {
    res.set({
      // nice to have, but Chrome dont seem to mind either way
      'Access-Control-Allow-Origin': '*',
      // right content type prevent warnings and errors
      'Content-Type': 'text/javascript; charset=UTF-8',
      // optional, this is in seconds, equivalent to 8h
      'Cache-Control': 'public, max-age=28800'
    });
    return res.send(200, "" + req.query.callback + "(" + JSON.stringify(myAwesomeResource) + ");");
  } else {
    return res.send(200, myAwesomeResource);
  }
});

In the client:

// see the data in your console
$.getJSON("http://myawesomewebsiteurl/my-unique-endpoint?callback=?", function(data){ console.log(data) } )

Caveats

jsonp is works for GET verb, because it effectively execute the code received as if it was downloading a script.
for the same as above, the source should also be fully trusted!

Loggly middleware for Express.js (server visibility)

Hi!

Oh how long without posting, I’ve been missing it dearly, but in transition between jobs I was super busy, and now I can take the time to add some cool stuff =)

Use Case

I’ve been building an API, it is very cool, but the visibility for it is naturally low compared to websites. Loggly offer a great service for monitoring servers via a simple API available in node.js. While this API is cool, it is super broad and require some experimentation to implement an adequate visibility level.

Wouldn’t be amazing to be able to see every request that come in your server and how it respond? Utopic? Absolutely possible!

Implementation

This implementation has been heavily inspired by Connect logger middleware – which is great.

I deeply recommend you to tune it for your visibility needs, though. Make good use: https://gist.github.com/flockonus/5380753

// suggested use:
app.configure(function() {
  app.set("port", process.env.PORT || 3005);
  app.use(logglyMiddleware);
  // ..
  app.use(express.bodyParser());
  app.use(app.router);
  // ..
});

Notes worth taking

• This snippet will show you information in your console when o development
• The info sent might be too much in terms of size or frequency, make good use of customization for your needs
• If you are dealing with a website, I advice you to not send every path hit, it is just too much

Cheers!

Posting a photo (as a business) to a Facebook Page via JavaScript SDK

The Facebook Javascript SDK (API) is not so well documented, what makes not so logical to post to a page, using it. For that I am about to show, make sure your connect scope having at least: “manage_pages,publish_actions,publish_stream”.

I am assuming you already succeeded providing login to the user; if this is not the case, refer to the docs.

We rely heavily on the FB.api method, the docs make a poorly job documenting, but is a starting point anyway. Also, notice the response is async.

Fetch all user pages (actually the first 5k), but only store the first as var page (this is just a sample)

var page = null;
FB.api('/me/accounts', function(response) { console.log(response); page = response.data[0]; })

Now, we want to publish a post to the page timeline, the thing is, we are not posting as ‘me’ anymore, we must post as the page, and it requires both the id and access_token!
I will make a sample function for it, the response is the post id if it all went well, or an error.

function postToPage(page, msg){
  FB.api('/'+page.id+'/feed', 'post', { message: msg, access_token: page.access_token },
    function(res) { console.log(res) }
  )
}
postToPage(page, 'hello fb-page world')

For last, posting a picture requre the url param, like so:

function photoToPage(page, src, msg){
  FB.api('/'+page.id+'/photos', 'post', { url: src, message:msg, access_token: page.access_token },
    function(res) { console.log(res) }
  )
}
photoToPage(page, 'http://24.media.tumblr.com/tumblr_m1ttif5puW1qcrr0lo1_500.png', 'nyan art')

* Don’t try to run all functions in sequence, since the result comes asynchronously you wont have the var page set.

** kudos for Владимир Дворник answer on Stack Overflow for the url param not documented in the Page Graph API.

*** Security note. The JavaScript SDK can be very unsafe in the case a hacker is able to inject JS code in your page (and even happens in Twitter all the time even though they have millions in funding) they may take advantage of all of the user’s permissions.

Done!

ImageMagick on Joyent

It is really simple:


pkgin search ImageMagick # you will get some result like this:
ImageMagick-6.6.6.5 Package for display and interactive manipulation of images
p5-PerlMagick-6.6.6.5 Object-oriented Perl interface to ImageMagick
php53-imagick-5.3.5.2.2.2 Provides a wrapper to the ImageMagick library
ruby18-RMagick-2.13.1nb3 Ruby binding to ImageMagick
ruby18-mini-magick-2.1 Ruby wrapper for ImageMagick command line
ruby19-RMagick-2.13.1nb3 Ruby binding to ImageMagick
ruby19-mini-magick-2.1 Ruby wrapper for ImageMagick command line


Now, install the latest version, today it is 6.6.6.5, so run:

pkgin install ImageMagick-6.6.6.5


Done!

For the Node.js package “imagemagick” at “0.1.2” works for my use cases, which are just resizes 🙂
If you are using other languages you may need the other packages as well.

Mongoose validate unique field (insensitive)

Making a validation function for Mongoose (Node.js – MongoDB ODM) that checks upon validation field.

function uniqueFieldInsensitive ( modelName, field ){
	return function(val, cb){
		if( val && val.length ){ // if string not empty/null
			
			var query = mongoose.models[modelName]
				.where( field, new RegExp('^'+val+'$', 'i') ) // lookup the collection for somthing that looks like this field 
			
			if( !this.isNew ){ // if update, make sure we are not colliding with itself
				query = query.where('_id').ne(this._id)
			}
			
			query.count(function(err,n){
				// false when validation fails
				cb( n < 1 )
			})
		} else { // raise error of unique if empty // may be confusing, but is rightful
			cb( false )
		}
	}
}

Then call it to a field (aka path):

UserSchema.path('nick').validate( uniqueFieldInsensitive('User', 'nick' ), 'unique' )

Recommend you organize all validations in a file for itself, or even a folder if grows too big.

If you have a unique index set for the path you may just save it and check for the error raised; the thing is the format of the error.

Basic Authentication on Node.js – Express and Mongoose

via Axiom Zen

Hello!

This post is about the most important parts I can think of implementing signup and login to Node.js powered by Mongoose and Express.js.

This post have a huge audience, but guys, please keep in mind that this post was done a while ago. It works pretty well as a cook-book, but there probably are better options for achieving this nowadays, new npm packages and such.

Implementing last night, I was impressed on how fast had the functional part done (around 3 hours), pretty much the same time I’d had it done in Rails (if not faster).

Goal:

• 3 urls: GET login & signup, POST login, POST signup.
• User fields: email, nick, password(encrypted).
• Validate (and show) messages for all fields.

I’ve setup a small Github project that may be used as example (assuming you have mongoDB installed and running in localhost) – DOWNLOAD IT FROM GITHUB  

Model: user.js

var Schema = mongoose.Schema
  , ObjectId = Schema.ObjectId
  , Validations = require('./validations.js')
  , salt = 'mySaltyString'
  , SHA2 = new (require('jshashes').SHA512)()

function encodePassword( pass ){
	if( typeof pass === 'string' && pass.length < 6 ) return ''

	return SHA2.b64_hmac(pass, salt )
}

var UserSchema = new Schema({
    nick        : {type: String, required: true, unique: true, trim: true }
  , email       : {type: String, required: true, unique: true, trim: true, lowercase: true }
  , password    : {type: String, set: encodePassword, required: true }
});

UserSchema.statics.classicLogin = function(login, pass, cb) {
	if( login && pass ){
		mongoose.models.User
			.where( 'email', login )
			.where( 'password', encodePassword(pass) )
	  	.findOne( cb )
	} else {
		// just to launch the standard error
		var o = new this({nick: 'VeryUniquejerewelA', password: '', email: login+'aaa'})
		o.save(cb)
	}
}
UserSchema.path('nick').validate( Validations.uniqueFieldInsensitive('User', 'nick' ), 'unique' )
UserSchema.path('email').validate( Validations.uniqueFieldInsensitive('User', 'email' ), 'unique' )
UserSchema.path('email').validate( Validations.emailFormat, 'format' )
UserSchema.path('password').validate( Validations.cannotBeEmpty, 'password' )
UserSchema.plugin( mongoose.availablePlugins.timestamper )

mongoose.model('User', UserSchema)

.Highlights of this code: We are using the package jshashes, which supplies many convenient encryption methods, among those SHA512 –strong enough
It is a good practice to use a salt along, represented by the var salt. In practice it makes way difficult for a cracker that acquired access to the database do decipher the passwords stored.
The method encodePassword is used at two occasions, when setting the User password, and when retrieving it from database.
UserSchema.statics is a object that stores additional static methods our User model will offer.
The function classicLogin requires both login and pass to search the db for existence, otherwise, it will launch an error (kinda of a smelly workaround to make it work dry )
UserSchema.path(…).validate offers us validations, in our case, we do not allow repeated email or nick, and password should be bigger at least 6 characters long. Also email should at least look like a email.
All those validations work along with the own Schema definition: required, unique, trim, lowercase

Route: auth.js

// app.get( '/auth/popover', auth.popover);
exports.popover = function(req, res){
	//req.session.popover = new Date()
	console.log('My session:', req.session)
  res.render('auth/index_pop', req.viewVars);
};

// CLASSIC LOGIN / SIGNUP       --because everyauth seems too messy for login+pass
// app.post('/auth/classic-signup', auth.classicSignup)
exports.classicSignup = function(req,res,next) {
	if( !req.body ){
		console.log('why u signup nobody?')
		return res.redirect('/?nobodySignup')
	}

	var user = new app.models.User()

	user.set('nick', req.body.nick)
	user.set('email', req.body.email)
	user.set('password', req.body.pass)
	user.set('providers', ['signup:'+user.get('email')])
	user.set('profiles', [{ _name: 'signup'}])

	user.save( function(err) {
		if( err ){ // validation failed

			req.viewVars.u = user
			return classicYieldErr( req, res, 'signUp', err)

		} else { // signup successful

			req.session.user = {
				provider: 'signup',
				id: user.get('id'),
				nick: user.get('nick'),
			}

			req.flash('notice', 'Welcome!')
			req.viewVars.welcome_login = "Welcome, "+user.nick

  		res.render('auth/win_pop', req.viewVars )
		}
	})
};

// app.post('/auth/classic-login',  auth.classicLogin)
exports.classicLogin = function(req,res,next) {
	if( !req.body ){
		console.log('why u login nobody?')
		return res.redirect('/?nobodyLogin')
	}

	app.models.User.classicLogin( req.body.email, req.body.pass, function(err, user) {
		if( err ){ // validation failed

			return classicYieldErr( req, res, 'signIn', err)

		} else {

			if( user ){ // login

				req.session.user = {
					provider: 'signup',
					id: user.get('id'),
					nick: user.get('nick'),
				}

				req.flash('notice', 'Welcome!')
				req.viewVars.welcome_login = "Welcome, "+user.nick

	  		res.render('auth/win_pop', req.viewVars )

			} else { // not found
				return classicYieldErr( req, res, 'signIn', {errors:
					{'loginpass': {
						name: 'V',
						path: 'login+password',
						type: 'loginpass'
					}
				}})
			}

		}
	})
};

// display form error
function classicYieldErr( req, res, mode, err ){
	req.viewVars.erroredForm = mode
	if( mode === 'signIn' ){
		req.viewVars.signin_errors = app.helpers.displayErrors( err )
	} else {
		req.viewVars.signup_errors = app.helpers.displayErrors( err )
	}
	req.viewVars.email = req.body.email

	res.render('auth/index_pop', req.viewVars);
}

Here we define the 3 routes;
– one route(GET) that defines one page for both login or signup
– one route(POST) to submit login
– one route(POST) to submit signup
About the last 2, their only role is to allow access for valid data. That is, valid signup data, or login+password existing in our collection from MongoDB.
The function classicYieldErr is there just to serve the errors in sort of an uniform way. We will see about this function on the next file

Model Helper: validations.js

exports.uniqueFieldInsensitive =  function ( modelName, field ){
	return function(val, cb){
		if( val && val.length ){ // if string not empty/null
			// only for new docs
			if( this.isNew ){
				mongoose.models[modelName].where(
					field, new RegExp('^'+val+'$', 'i')
				).count(function(err,n){
					// false when validation fails
					cb( n < 1 )
				})
			} else {
				cb( true )
			}
		} else { // raise error of unique if empty // may be confusing, but is rightful
			cb( false )
		}
	}
}

exports.emailFormat = function( val ){
	// false when validation fails
	return (/^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i).test( val )
}

exports.cannotBeEmpty = function( val ){
	console.log('pass val is:', val)

	// not all passwords should be set, BUT when string, should be encoded
	if( typeof val === 'string' ){
		if( val.length ){ // when it comes empty, something went wrong!
			return true
		} else {
			return false
		}
	} else {
		return false
	}
}

This file contains some very important function, being intuitive, I will only comment on the first.
uniqueFieldInsensitive is actually a validation creator. It uses JS’s closure ability along with the powerful this object to wrap the context where this will represent whichever Model is calling it.
The intent of the function is to search the db for any repeated occurrence of the field, case-insensitive. This way the system will block a user “John” from signinup, if “john” is present.

Helper: form_helper.js

//app.helpers.displayErrors = require('./helpers/form_helper.js').displayErrors

stripErrors = function(mongooseErr){
	var prop, list = [];
	for( prop in mongooseErr.errors ){
		list.push( [mongooseErr.errors[prop].path, mongooseErr.errors[prop].type] )
	}
	return list
}

/*
 * Translate mongoose errors into a <li> of errors
 */
exports.displayErrors = function( mongooseErr ){

	console.log( 'mongoose errs', mongooseErr )

	var list = stripErrors( mongooseErr )

	var output = []
	list.forEach(function(e,i){
		switch( e[1] ){
			case( 'unique' ):
				output.push( e[0]+" is taken" )
				break;
			case( 'required' ):
				output.push( e[0]+" is "+e[1] )
				break;
			case( 'format' ):
				output.push( e[0]+" has a bad format" )
				break;
			case( 'password' ):
				output.push( "password should be at least 6 char long" )
				break;
			case( 'loginpass' ):
				output.push( "login+password not found" )
				break;

			default:
				output.push( e[0]+": "+e[1] )
				break;
		}
	})
	if( output.length ){
		// condense all items in an error list
		output = [output.join( '</li><li>\n' )]
		output.unshift( '<ul><li>' )
		output.push( '</li><ul>' )

		// wrap in a div
		output.unshift( "<div class='error block'>" )
		output.push('</div>')
	}
	return output.join('\n')
}

This file provides a translation from Mongoose errors to user-readable errors. In order to offer a good UX, it is important to give accurate feedback. Notice this file could benefit from some refinement 🙂

Don’t forget to download the code from github, it plays well along everyauth module 🙂

Cheers!

Read QR code from Javascript and Webcam

Problem

Here, at Flockin we needed a way to login from Browser using a QR-code card and the Webcam.

For the time being (ealy 2012), Javascript have no API to stream/parse from webcam, also the main free library for QR code, Google’s ZXing (actually the only one working I know of) does not support Javascript.

Solution

The most viable solution detected was to parse Webcam from ZXing’s ActionScript module, in a very dry package that could interact with JavaScript through ExternalInterface with Javascript registering a callback.

Use

The use is pretty simple. When the swf object gets completely loaded on the page just register the JS callback which is a function that takes 1 param (String or null), the Interval of call (default 500), and an error callback (default null)

You can download all files from github, that is the project home. *Recommend you adapt the .as3 and recompile to fit your specific needs

CODE

The example below is the same found at the project’s example/index.html

// sample of function that may be registered as Callback.
function actQR( msg ){
	// msg comes null if no code were detected
	if( msg === null ){ //expect a lot of nulls
		console.log("no QR were read at this time")
	} else {
		// a valid QR reading, do something with it
		console.log(msg)
		// ask flash to stop parsing, this saves processing as webcam reading stop
		QR.stop()
	}
}

// sampe of function to be called when something goes wrong
function noWebcam( msg ){
	alert("Err! "+msg)
}

// this setInterval is a safe measure, so we don't call flash function before it is loaded;
var registerQRCb = setInterval(function(){
	//var nomeDoFlash = "QR"
	if( typeof QR === 'object' && QR != null && typeof QR.start === 'function' ){
		clearInterval(registerQRCb)
		// first param is the function signature we want the SWF to call periodicaly
		// second param is the intervall we want it, in miliseconds (default: half-second)
		// third is an signature for callback if something goes wrong, aka, user has no Webcam (default: null)
		QR.start( "actQR", 200, "noWebcam" )
	}
}, 100)

Ruby’s fear-cancer

This video: High Performance Ruby: Threading Versus Evented by Dr Nic Williams, Engine Yard

It meant so much to me!

For around 4 months I’ve been using Node.js, and before that, for 3 years, programming Rails.

As soon as I started on Node.js, I could feel that something was different. My little Computer Science bachelor conscience was starting to tell me: now you are starting to do it right 🙂

But then, lets go back, Ruby’s syntax is lovely.. Rails API is sugar! But still, it’s neverland. Why??

It does not fit real world! It is a thin layer of happiness, so delicate, that we feel fear of touching it and breaking it. So what we puny humans do? We delegate it to those genius heroes who will be able to take that code and maybe squeeze a few more couples of requests/sec!

But not even that is the cancer I mean.

The cancer here is represented by clown hosting the video. “Oh those scientific articles mess with our head and stuff O.o Let me chew that evil reality and I will give you the RIGHT (sugar coated) solution!” and all other non fun nor assertive statements. By the way, he may be referring to the C10K problem, and alike, articles.

The problem here is, VP  EngineYard and want ppl addicted on his junk. He does not host Node.js.

Ruby always had so many language implementations to solve some important language problems, as well as servers. This is not the first time a good solution for ruby is born (JRuby+Trinidad), but why would they share it before if he could have people paying for so much RAM?

The reason I believe he felt compelled to share it now, is that Node.js unoptimized code can outperform Rails by a LOT,  under 150Mb.

But my main problem is fear of complexity. The host talks about it all over the initial part of the video. He refers his audience under constant fear of it’s own ignorance all the time. This is a awful, and that’s how I felt using Rails. Such a large stack, complex language design, only understanding the framework code itself was hard task.

To keep people in bliss ignorance he just goes like: “Oh I promissed evented? We are past that, right?! HAAAA” so just be happy and keep the status quo. You would’t want to mess your pretty little head with asynchronous code, would you?

I like Node.js, besides performance, language is simple; it is JavaScript, open Objects, closure and more. Of course, don’t assume well-written JS is something easy to do. No great code in any modern language is easy to achieve.

If you’ve developed Rails, you have concepts of MRI, thin, mongrel, jruby, 1.8.7, 1.9.2, rubinius, unicorn, and LOT MORE, whilst in node.js world all that stands for: node.js. It is a unification point for language and server.

What about gems?  npm, a easier system of distributing packages.

Wrapping it up, node.js is no silver bullet, it just made me realize the problems I had while programming ruby, as much as ruby did it for me on php. If nothing else, node.js helped improve ruby’s community by adding options to the web development mainstream.

Would I work with Rails again? If a employer would point me that out as the only chosen solution, then yes, and I’d probably try that stack, but I prefer confidence instead of fear.

When to Ruby on Rails, when to Node.js

(update) Take this post as a naive overview, it may not reflect the most accurate reality

Hello!

I am trying to do a sort of indirect comparison between Rails and Node.js. The very main reason of being indirect, is that Rails is a Framework, while Node.js is a runtime with custom libraries.

If it were be to put in a simple phrase, Rails is resourceful and Node.js is light and fast.

Lets elaborate some more..

Rails

Is the most complete open-source framework available (that I know of)! Big companies use it. It can do lots of stuff well, in an organized manner; this meaning, Rails is more than just MVC, it has a full stack of features well-integrated, at the same time being very modular. Some of the features included out of the box:

• Database adapter for the majority of them, supporting plug your own.
• Database migrations, so multiple dev can sync and experiment with their DB.
• Powerful engines for Views, Controllers and Models.
• Support to code generator.
• Has structure to all sorts of tests and friendly to TDD.
• Really awesome documentation.
• Model has all kinds of hooks, validations and associations.
• Controller has support to handle XML/JSON in the same action that serves HTML.
• Gems that integrate, for instance, Memcached, MongoDB, Auth and lots more.

So Rails is war-proven, capable of integrating lots of features together without harass. There is also a very cool post of Fabio Akita in the refs. about how it made possible to develop systems in periods before impossible.

Node.js

Two things make this platform suitable for web:

Its engine, V8 is very fast! In a very loose average, 8 times faster than Python (or even up to 200 at peak). Python already outperforms Ruby (ref. bottom)

Second point; and this argument is separated from the above, is that it async-driven (is built around reactor pattern). As in the case, requests can be performed in parallel, without any blocking I/O. A single server can handle a lot. (update) And with >0.6.0 Cluster API, it can scale to use all of available CPU cores.

So, it is a very new sort of backend language, but huge players, besides Joyent, who invented it, are adopting it, including LearnBoost and LinkedIn, which has an awesome article about using. The language, and it’s main web framework, Express, deserve a list of features (you can check more info in the references below).

• It´s web server is able to handle a HUGE number of connections out of the box
• Various libraries can be run on browser, the same as in the server
• Very friendly to Websockets (real-time web apps)
• Lots of libraries are being ported to it from other langs.
• Express, inspired in ruby´s Sinatra; is very light on memory but also very powerful

Running a simple benchmark against a single server instance, I were able to get 587 req/s accessing MySQL without any external cache support. This number could scale, if I used Cluster to spawn at least a process per processor.

Summarizing, When to use each?

Rails really shines when..

• The database is complex in terms of associations.
• The app structure is well defined.
• Business rules are complex, and validation is needed.
• When the number of requests isn´t the a decisive factor.
• Administrative interfaces.
• Many developers in parallel keep the DB up-to-date with migrations
• The database to be used is undefined, or may vary.

What about Node.js?

• APIs
• Real-time web/mobile apps.
• Application that should scale to lots of concurrent requests.
• Little memory footprint

This being said, there is no reason at all, a web-site or service can´t easily integrate both.

— I’d appreciate if you could leave a comment, either to talk about your case, or add up.

References

 

UPDATE: http://www.mikealrogers.com/posts/a-new-direction-for-web-applications-.html

http://guides.rubyonrails.org/

http://railscasts.com/

http://blog.heroku.com/archives/2011/6/22/the_new_heroku_2_node_js_new_http_routing_capabilities/

http://nodejs.org/

http://akitaonrails.com/2011/04/16/twitter-muda-de-ruby-para-java-ruby-e-3x-mais-lento-que-java

http://venturebeat.com/2011/08/16/linkedin-node/

http://blog.bossylobster.com/2011/08/lesson-v8-can-teach-python-and-other.html

https://github.com/LearnBoost

http://www.readwriteweb.com/hack/2011/01/how-3-companies-are-using-node.php

http://twitter.com/#!/FlockonUS/status/104655096956190720

https://github.com/LearnBoost/cluster