part1

part2

part3

Multiple cores: norejs clusters

Multiple machines: nginx link1, link2  Have multiple machines each running the same replica of server, run nginx reverse proxy to load balance between them

$ npm install -g nodemon   //automatically restart. make sure you call the start script section of package.json   like   node-dev   module

function getMethods(obj) {

  var result = [];

  for (var id in obj) {

    try {

   //   if (typeof(obj[id]) == "function") {

        result.push(id + ": " + obj[id].toString());

    //  }

    } catch (err) {

      result.push(id + ": inaccessible");

    }

  }

  return result;

}

Non-blocking I/O

Whenever we want to do a blocking I/O we register a call-back function - hence make it non-blocking! So we don't actually wait for bit.ly to return with a response.      Reactor is what handles the non-blocking

• Eventually non of these requests are running side by side, but they are running one at the time -
• The main benefit is that during red segments we can handle new requests.
  
• So in Node each process can handle multiple requests unlike rails e.g. that each process does only one.
• So, we don't have to start as many node processes as we would with ruby for the same amount of load
• Response latency is first. if you only have one user these don't differ from ruby to node
• node is hard to read, leads to spaghetti of nested callbacks
• Rails has event manager for evented programming and callbacks.
• We are scheduling the I/O by ourselves. in Ruby programming we are unaware of IO
  

Node.js vs Python

Standard Python is actually slower in 46 of the 50 problems. In 28 of the 46 node is faster by a factor of 10 or greater, in 9 of those 28 by a factor of 50 or greater and in 2 of the 9 by a factor of 100 or greater! The only 4 in which Python was faster were from the n = 10000 sample.

$ vim hello-world.js
  setTimeout(function(){
      console.log("world");
   }, 2000)
   
   console.log("Hello ");

In node.js you never sleep, no mutex, lock, etc

PHP:

  echo("Hello");

  sleep(2) //sleep!!!

  echo("World")

returns when there is nthing left to do

$ vim hello-world-interval.js

setInterval(function(){
      console.log("world");
   }, 2000)
   
   console.log("Hello ");

hello

world

world

world
...

$ npm install --save express   # to install and save it in package.json

Node Packaged Modules (NPM)

$ mkdir myproject

$ cd myproject

$ npm init                                             # Morteza Shahriari Nia <m.shahriarinia@gmail.com>

$  npm install --save express               # download dependency and add its version details to package.json      

$ vim index.js

var http = require('http'),

      express = require('express');

var app = express();

app.get('/', function(req, res) {

    res.end('Airline');

});

http.createServer(app).listen(3000);

$ node index.js

Global modules

$ sudo npm install -g express-generator       # creates express as a global module and as a commandline command for generating express modules    

$ express mynewproject

$ cd mynewproject

$ npm install

$ npm start    # runs the node index.js of the project as declared in the package .json

you can remove a dependency from package.json then call

$ npm prune  # to remove its directory

you can manually add a dependency to package.json. * declares use the latest version

    "jade": "*"

$ npm update   # will update the modules

Cool Modules

readline

jquery

use jquery without web browser

var argv = require('optimist').argv,
    $ = require('jquery'),    
    fs = require('fs');

var file = argv._[0];

var html = fs.readFileSync(file, 'UTF-8');

$(html).find('p').each(function(index) {
    var content = $(this).html();

    console.log('Paragraph ' + (index + 1) + ': ' + content);
});

jshint     # detect potential problems with your code before you actually run it. Use its sublime package. command shift j

connect  # for static content ; Connect makes it possible for you to handle multiple kinds of requests by chaining calls to connect to use.

var connect = require('connect');

var app = connect()
    .use(connect.static('public'))
    .use(function (req, res) {  //error handling
        res.end("Couldn't find it.");
    })
    .listen(3000);

=========================

var connect = require('connect');

var app = connect()
    .use(connect.bodyParser())
    .use(connect.static('public'))  //serve anything that is static in public directory e.g. if you put the index.html there
    .use(function (req, res) {   //the rest
        if (req.url === '/process') {
            res.end(req.body.name + ' would repeat ' + req.body.repeat + ' times.');
        } else {
            res.end("Invalid Request");
        }
    })
    .listen(3000);

=========== modify http parameters

        res.setHeader('Content-Type', 'application/json');
        res.end(JSON.stringify(my_data));