Node.js is a JavaScript runtime environment that allows building fast, scalable network applications using event-driven, asynchronous I/O. It uses Google's V8 JavaScript engine and can run on Windows, Mac OS, and Linux. Node.js is commonly used for building servers, APIs, real-time apps, streaming data, and bots. Typical Node.js apps use NPM to install packages for tasks like databases, web frameworks, testing, and more. Node.js handles non-blocking I/O through callbacks to avoid blocking and optimize performance. A basic HTTP server in Node.js creates a server, handles requests, and sends responses.

2. What is Node JS?
 A JavaScript runtime environment running Google
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Chrome’s V8 engine
Node.js is a platform for building fast, scalable network
applications (web servers).
Server - side JavaScript
Uses event-driven, asynchronous I/O to minimize overhead
and maximize scalability
—Great for data-intensive, real-time applications

3. V8 JavaScript Engine
 V8 is written in C++ and is used in Google Chrome
 Runs on Windows (XP or newer), Mac OS X (10.5 or newer), and
Linux systems that use IA-32, x64, or ARM – you can install your
server on many devices.

4. What can NodeJS be used for?
 Network servers (HTTP, messaging)
 API backends
 Real time applications
 Streaming data
 Web sites
 Bots

5. Typical architecture

6. Node Package Manager (NPM)
 NPM is a package management and distribution
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system for Node
you can quickly find packages to serve specific
purposes
An npm package is a directory structure with a
package.json file describing the package
Total Packages: over 31 000
can be installed simply by typing the following:
npm install moduleName

7. Node Package Manager (NPM)
 Databases: mysql, postgresql, mongodb
 DOM: jsdom
 Web frameworks: express, connect
 DOM Manipulation: jQuery
 Utility libraries: underscore ,backbone, request
 Templating: mustache, jade
 Testing: vows, expresso

8. Non-blocking I/O
 Servers do nothing but I/O (Scripts waiting on I/O
requests degrades performance )
 To avoid blocking, Node makes use of the event driven
nature of JS by attaching callbacks to I/O requests
THE NODE WAY
fs.read('very-big-file', function(data) {
complexOperation(data); }
);
// you can do a lot when waiting for data
doOtherStuff();

9. Blocking vs Non-Blocking flow

10. Basic HTTP Server
CODE:
http = require("http");
http.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/plain'});
res.write(“Start Hello");
res.end('Hello Worldn');
})
 when ‘stuff’ happens my function fires
 I get a request object and a response object
 I write to the response object header HTTP status 200
(Standard response for successful HTTP requests) and
content-type ‘text/plain’
 We make changes to the response object and then these are
transmitted when we call: esponse.end();

11. Basic HTTP Server
 This line requires the http module that ships with Node.js and
makes it accessible through the variable http.
 var http = require("http");
server = http.createServer(function(request, response) {
response.writeHead(200, {"Content-Type": "text/plain"});
response.write("Hello World");
response.end();
}).listen(8888,”127.0.0.1”);
 We pass a function into the server which it uses to handle all
incoming requests.
 When ‘stuff’ happens call this anonymous function
 Listen on port 8888 of the ip 127.0.0.1

12. http.ServerRequest Object
 When listening for request events, the callback gets an
http.ServerRequest object as the first argument. This
object has methods and properties:
 req.url: This property contains the requested URL as a
string. It does not contain the schema, hostname, or
port, but it contains everything after that.
 req.method: This contains the HTTP method used on
the request. It can be, for
example, GET, POST, DELETE, or HEAD.
 req.headers: This contains an object with a property for
every HTTP header on the request.

13. http.ServerResponse Object
 Writing headers: res.writeHead(status, headers)
 Changing or setting a header res.setHeader(name, value);
 Writing a Piece of the Response Body:
res.write('Hello');
 or use an existing buffer:
var buffer = new Buffer('Hello World');
res.write(buffer);
 Streaming a mp4
var fs = require('fs');
require('http').createServer(function(req, res) {
res.writeHead(200, {'Content-Type': 'video/mp4'});
var rs = fs.createReadStream('test.mp4');
rs.pipe(res);
}).listen(4000);

14. Basic node JS Module
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var mysql
= require('mysql');
var connection = mysql.createConnection({
host : 'localhost',
user : 'nod',
password : 'nodejs',
database : "test"
});
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function connectDatabase() {
connection.connect();
console.log("db connected");
}
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//insert data to database and call the function received
function insertDatabase( data , callback ) {
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exports.startDatabase = connectDatabase;
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exports.insertDatabase = insertDatabase;;
connection.query('INSERT INTO users (user) VALUES (?)',[data.clientName], function ( err, result ) {
if (err) throw err;
//calling callback function from server-chat.js
callback ( result.insertId );
});
}

15. Example
 Free Spark implementation:
http://10.182.39.2/

16. Cosmin Mereuta