Getting Started with J2EE, A Roadmap

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Getting Started with J2EE Architecture And Stack Overview

Mak’arand Bhatamrekar [email protected]

Passionate building Apps with Java and RIA GWT,Flex

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Agenda

In this session, we will see the • Web Basics– From Static Pages to Enterprise solutions– Why J2EE

• Basic Webconcepts• Http Protocol • Overview of Design Patterns• J2EE Stack Overview like Spring MVC, EJB, Hibernate,

Webservices etc• Get Started• Assignments

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Web Basics

Browsers only understand HTML along with JavaScript and CSS.

Webserver is an application running on a machine serving HTML pages.

Browsers communicate with Webserver using HTTP Protocol

HTTP Protocol, uses mostly GET and POST requests retrieve the Page. Protocol is a set of Rules which two systems follow to communicate.

A request like http://www.google.com, finds its way to Server with its corresponding IP Address address lookup called DNS

Along with IP Address, we also need to know the Port no(its like room no), on which the webserver app is running. Default port is 80.

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At First Websites were static HTML with JS and CSS

• Web Servers are Apache WebServer • Every developer needs to know

HTML basics• JavaScript is a scripting lang which

runs at browser end. (It is very powerful now with Jquery, JSON and others)

• CSS is used to Style the application by designers

• HTML pages stored on webserver are requested by browser with HTTP protocol

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HTTP Protocol Request Types/Verbs: Developer Essentials

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Switching Gears : Building Dynamics Web Solutions

• Today websites are everyday part of our life– For paying bills, shopping, information and so on

• Web solutions are Dynamic in Nature – The content varies as per context e.g your mail.

• These web solutions need to support various client from browser to phones, tablets.

• Need to be scalable, say support 1000’s of users.

• J2EE is the one of main technologies is used to build such websites.

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Why Java J2EE

• Open Source : 100 % free• Huge Community, lot of Jobs• Enterprise Language• Defacto Enterprise Lang• Production platform Linux : 100% free• SLA’s available• Lot of choices like Spring, Struts, JSF, Jboss Seam etc• Java is a Platform now, with Groovy,Scala,Jruby build

around it

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Design Patterns

• MVC is the base design pattern for all the J2EE frameworks• They are proven solutions to recurring problems. • Very essential for J2EE Developer• Need to remember the Problem and Proven solution for it

Assignment• Research on MVC, Singleton, Factory Design Patterns: Find the problem they solve and the Solution

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Dynamic Web Apps - MVC 1 / J2EE Spec

• MVC1 Design Pattern • MVC 1 drawbacks

– No clear separation– Controller can act as View

and Model• HTTPServletRequest and

HTTPServletResponse objects carry data back n forth

• Servlet uses ServletContext.requestDispatcher to call the right JSP based on the success or failure outcome

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Next,Web Solutions with MVC2• Struts, Spring MVC and

others• No Servlet to write , Struts

gives ActionServlet, Spring gives DispatcherServlet

• XML Configs direct the servlet for URL redirection e.g Struts-Config.xml.

• XML Configs also do Localization,Validation,Interceptors,JavaBean conversion etc

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Now we have arch which supports difft clients

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We keep exchanging terms

Web Server Web Container Application Server

e.g Apache WebServer e.g ApacheTomcat, Jetty e.g Jboss,Weblogic,Websphere

Serves only static HTML pages

Serves Dynamic pages like JSP

Same as WebContainer

Supports HTML Supports JSP, Servlet,SOAP request

Supports all + EJBs

No Compliance needed Supports part of J2EE Spec 100% compliant with J2EE Spec

Fast,lightweigth Fast,lightweight Heavy

Good for designing Good for developers Good for Production

Takes requests and redirects to servers as needed

Now a days even good for Production,

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Lets Get Started , Softwares

Install the Softwares to get started• *Eclipse IDE : Eclipse is the defacto IDE (

www.eclipse.org)• *Apache Tomcat : A light weight Application

container to develop Web Applications

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Course RoadMap

We will start attacking from

• UI End : HTML, Java Script

• Middeware : Java Technologies

• BackEnd : SQL, JDBC, Hibernate

• Methodlogies : Agilet, DesingPatters,Coding Techniques etc

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Assignments

• Write a HTML Page – Write on notepad and run it on browser– Write Hello World HTML Page– Create Contact Us Form page Need some help, check out this video on CSS-Trickshttp://css-tricks.com/video-screencasts/58-html-css-the-very-basics/

• Find more info on HTTP protocol and status codes• Install Eclipse IDE for Java EE developers

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& A

Next Steps• CoreJava

HandsOn Coding with Realworld Java Assignments

Thank You

• What is Approach to learn?A) Recommended Steps say for Web Services

1. Cover the Concept part 2. Do a small proof of concept3. Integrate it in a bigger Project4. Prepare from Interview point Of view