1. Pervasive Web Application
Architecture
Narendran Thangarajan,
IV year, CSE,
SSN College of Engg, Chennai.

2. Why are we studying this?
 You got a Phone
 And a Laptop.
 Task :
Order Meals from KFC

3. Why are we studying this?
 Why?
 So the traditional web applications
need to be tweaked!
 And thats why we are here. :)

4. The first person
who thought about this
is Mark Weiser.

5. 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.

6. 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

7. Scalability and Availability
 Ever-growing number of pervasive computing devices
(scalability)
 ”Server Currently Down for Maintenance” (availability)

8. 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.

9. Implementing a Pervasive Web Application

10. Development Team
 Traditional Web Applications
 Business Logic Designers
 User Interface Designers
 Application Programmers
 Database experts
 Pervasive computing Web applications
 Traditional + Pervasive Computing Specialists

11. 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.

12. 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.

13. 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.

14.  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.

15. Theory is BORING!

16. 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

17. User Interface Overview
 Registration
 Login Screen
 Menu
 Ordering
 Review Former Purchases
 Self Care
 Log Off

18. 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.

19. Thus..
 Understand how to make a single web
application handle requests from variety of
devices
 Understand the MVC
 Understand the Design Pattern used.

20. Queries?

21. Thats hell of a patience!! :P