Introduction to Node.js & JavaScript Platform

1. INTRODUCTION TO NODE.JS
SERVER-SIDE JAVASCRIPT & EVENT-DRIVEN PLATFORM
Naresh Chintalcheru

2. NODE.JS

Node.js is a platform to build fast, scalable and
high-throughput network applications

Uses single-threaded Event-Loop & NonBlocking I/O model that makes it lightweight and
efficient use of Server resources

JavaScript Runtime on the Server

Browser based IDE’s

No multi-thread locking burden on the runtime

3. JAVASCRIPT

JavaScript is an object-oriented and
functional style scripting language

Runs on a single-threaded runtime

Dynamic Typing and Prototype-based
var person1 = new Person(‘John’, ‘Smith’);
Type-of-Variable Vs Type-of-Value

4. JAVASCRIPT

Dynamic Typing and Prototype-based language
var person1 = new Person(‘John’, ‘Smith’);

No Person class but a Person Prototype
var Person = function() {
this.fname = "";
this.lname = "";
this.greet = function() {
console.log("Hi, I'm " + this.fname);
};
};

5. JAVASCRIPT INHERITANCE
var Person = function() {
this.fname = "";
this.lname = "";
};
var Employee = function() {
this.title = "";
this.salary = "";
};
Employee.prototype = new Person();

6. JAVASCRIPT FUNCTIONS

Functions are the first-class citizens

Pass around Closure functions makes EventDriven programming simple

Closures
 Pass
functions to the method parameters
 Method returns data or functions

7. SERVER-SIDE VS CLIENT-SIDE

JavaScript is born and live in the client-side
browsers

Has ability to run on the server-side

Server-side JavaScript will not have the
browser based global objects such as
Window & Document but does have objects
http/url etc provided by the Node.js platform

8. JAVASCRIPT RUNTIME

Node.js uses the Googles V8 JavaScript
Engine used in chrome browser

V8 Runtime Engine uses Heap memory for
JavaScript objects & functions

V8 has Garbage Collection for memory
management

V8 JIT (Just-In-Time) Compiler

9. NODE.JS
Understanding Node.js Code

10. NODE.JS
Node.js is Platform + Runtime
No need of a Web Server

11. NODE.JS SERVER
var http = require("http");
Callback function
function onRequest(request, response) {
console.log("Request received.");
response.writeHead(200, {"Content-Type": "text/plain"});
}
response.write("Hello World");
response.end();
http.createServer(onRequest).listen(8080);
console.log("Server has started.")

12. NODE.JS
Routes & Request Handlers are
Controllers/Models in MVC

13. NODE.JS SERVER
var http = require("http");
function onRequest(request, response) {
var pathname = url.parse(request.url).pathname;
route(pathname);
response.writeHead(200, {"Content-Type": "text/plain"});
}
response.end();
http.createServer(onRequest).listen(8080);
console.log("Server has started.")
Route Handles /AddEmp /SearchEmp

14. EXPRESS.JS
Express.js MVC framework for Node.js
(Similar to Struts, JSF & SpringMVC for JEE)

15. EXPRESS.JS
Express.js MVC Framework handles Routes,
Request Handlers and Views for Node.js

16. EXPRESS.JS
//start Express
var express = require("express");
var app = express();
//set the view directory to /views
app.set("views", __dirname + "/views");
app.set("view engine", "jade");
//Delete an Employee; Routes And Request Handlers
app.post('/employee/delete:id/', function(req, res) {
employeeProvider.delete(req.param('_id'),
function(error, docs) {res.redirect('/')}) ;});

17. EXPRESS.JS
//start Express
var express = require("express");
var app = express();
var routes = require('./routes');
Struts-config.xml
//set the view directory to /views
app.set("views", __dirname + "/views");
app.set("view engine", "jade");
app.get('/emplist', routes.emplist(db));
app.get('/addemp', routes.addemp);

18. EXPRESS.JS & SPRING MVC
//Express delete an Employee
app.post('/employee/delete:id/', function(req, res) {
employeeProvider.delete(req.param('_id'),
function(error, docs) {res.redirect('/')});
});
//Spring MVC delete an Employee
@Controller
public class SpringMVCController {
@RequestMapping(value = "/employee/delete", method = RequestMethod.GET)
public String delete(@RequestParam("id") String name, Model model) {
employeeDAO.delete(id);
return “deleteSuccess";
}

19. DATA PERSISTENCE
Node.js can access RDBMS and NoSQL
Databases

20. DATA PERSISTENCE
var mysql = require('mysql');
var conn = mysql.createConnection({ host :
“localhost:3700”, user : “uid”, password: “pwd” });
conn.getConnection(function(err, connection){
connection.query( “select * from table1”,
function(err, rows){ if(err) { throw err; }});
connection.release(); }
);

21. THANK YOU
Thank You