node.js

An intro to node.js

http://nodejs.org

What is node.JS

A server side JavaScript engine written by Ryan Dahl

  - Enjoys the fruits of the browsers war.
     Fast JavaScript VMs and JIT. Faster than the Ruby VM or

     the Python interpreter

  - Well suited for high I/O scenarios 
     web like request/response, reading files, network streams, or
     streams in general
  - Designed with async in mind and non blocking I/O
  - Active community generating tens of thousands
     extension modules

Node’s Goal is to provide an easy way to build scalable network programs

On the device node enables writing light web like services efficiently and quickly

Why node.js

- Non blocking I/O

- Code can be shared between the client and the server

- 60,000+ extension modules

- Cross platform and supported by Microsoft

Our team increased its coding velocity by x10 fold

Hello Node

var http = require('http');
http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello Node!\n');
}).listen(1337);

console.log('Server running at http://127.0.0.1:1337/'); 

The most basic http server implementation.

Event emitters

Many of the built in constructs in node inherit from the EventEmitter class. This allows developers to register handlers for events in the life of the different objects.

For example a request object.

      var http = require('http');
      
      var req = http.get('http://www.bing.com', function(err, res) {
        res.on('data', function(data) {
          console.log(data);
        });
        
        res.on('error', function(err) {
          console.error('Error in response stream', err);
        });
        
        res.on('end', function() {
          console.log('DONE FETCHING bing.com');
        });
      });
      
      req.end();
      
  

Streams

Node supports the notion of streams for abstracting efficient non-blocking access to system resources. Files, Network, Pipes, Crypto are a few examples which node abstracts as streams.

This allows for a powerful chaining syntax that provides the developer with a concise clear code that is highly efficient.

      
var fs = require('fs');
var zlib = require'zlib');
var http = require('http');

http.createServer(function(req, res) {
  var fileStream = fs.createReadStream(__dirname + '/static/index.html');
  var gzip = zlib.createGzip();
  req.writeHead((200, { 
    'Content-Type': 'text/html',
    'Content-Encoding': 'gzip',
  });
  
  // pipe the file into the gzip stream and right into the response stream
  // using efficient non-blocking I/O

  fileStream.pipe(gzip).pipe(res);
});