Pervasive Web Application Pervasive Web Application ArchitectureArchitecture

Narendran Thangarajan,

IV year, CSE,

SSN College of Engg, Chennai.

Why are we studying this?

You got a Phone And a Laptop.

Task : Order Meals from KFC

Why are we studying this?

Why? So the traditional web applications

need to be tweaked! And thats why we are here. :)

The first person The first person who thought about this who thought about this

is Mark Weiser.is Mark Weiser.

Why the name ”Pervasive” Web Applications?

Pervade = diffuse or spread through

Supports multiple devices

PC's WAP phones PDA's Voice only phones

Before Pervasive Computing – there were only PC based web applications

After Pervasive Computing – HP just closed its PC market! :D → Devices are in various other forms.

Challenges faced

Different Devices have different standards

WML for WAP - Monochrome

VoiceXML for voice interaction

HTML for PC's

Not just the looks, even the capabilities!! Say, a PC and WAP phone (Sounds like Silk, doesn't it?)

Major Challenges

Scalability – due to increased number of mobile phones

Availability – due to the type of application used – look up a meaning or order something

Scalability and Availability

Ever-growing number of pervasive computing devices (scalability)

”Server Currently Down for Maintenance” (availability)

The solution

Can be solved by implementing a scalable physical topology :

Adding more servers to the backend. Adding a backup server that would take-over during

accidents. Generally parallelism and redundancy.

Implementing the server using a more optimized stack

Eg : All three-tiers being implemented using JavaScript.

Implementing a Pervasive Web Application

Development Team

Traditional Web Applications Business Logic Designers User Interface Designers Application Programmers Database experts

Pervasive computing Web applications Traditional + Pervasive Computing Specialists

Pervasive Application Architecture

MVC Architecture M – Model – EJB V – View – JSPs C – Controller – Servlets

Challenge is to make the controller identify the type of device and serve accordingly.

Security!!

Encryption – Using Algorithms for confidentiality

Authentication – Username and Password

Authorization – Security Policies for accessing Application functions

Client to Web Application → Convert device-specific requests to canonical form (HTTP requests with device type, desired language, desired reply content-type)

When the secure access component receives a request, it checks if the session in authenticated. What happens in either cases.

Ways of Authentication

Authentication Proxy

Diagram Advantage – Only authenticated and authorized requests

can reach protected web applications.

Framework

Attaches an authentication object to the session. Secure Servlet – inherits HttpServlet – Securitypolicy check

done before calling super class function ”service” SecureJSP – Extends SecureServlet and implements

HttpJspPage AuthenticationServlets – Can be implemented in many ways

but SecurityState Object must be created and added to the user session.

SecurityState Object – holds the security state of a session

UserID Authenticated Method Potential Error Codes

SecurityPolicy class – accesses the policy database and decides whether to allow further processing.

Theory is BORING!

Example Application

How Java applications can be extended to support different kinds of device.

Scenario – Uncle Enzo's Shop Specializes in Italian Food Wants to improve ordering process for the

customers. First Step – Make an e-business Next Step – Support for Smart Cards

User Interface Overview

Registration Login Screen Menu Ordering Review Former Purchases Self Care Log Off

Architecture (Demo)

Database Schema

Store Persistent Data (UserData)

Servlets

Identify the Device type and call the appropriate controller (DeviceMapper and Registration Servlet)

Controllers

Process requests by invoking application logic via command (Registration controller)

Commands

Excapsulate access to models and act as result containters Views

Display the output of the controllers.

Thus..

Understand how to make a single web application handle requests from variety of devices

Understand the MVC Understand the Design Pattern used.

Queries?

Thats hell of a patience!! :P