1. Virtual ClassroomIntegrated Learning environment over internet Anshu Veda Prajakta Kalekar Shruti Mahambre

2. The Client

This project has been sponsored byIntel

IIT B point of contact

Prof. Umesh Bellur

3. Problem Definition

This project aims at putting together anintegratede-Learning environment for a university student.

This will also be used bydistance educationprograms offered by institutes, in order to enable students to avail of the academic facilities from any computer connected to theinternet .

4. Basic terminology

RMI (Remote Method Invocation)

Server application creates remote objects, makes references to them available and allows clients to invoke methods on these remote objects.

RMI tunneling over HTTP

Combines the benefits of HTTP tunneling and RMI over internet

EJB

• Session Beans (verb)

• Model business processes.They represent actions

• Entity Beans (noun)

• Model Business data They are data object, javaobjects that cache database information

EJB Container

• House enterprise beans and make them available for clients to invoke remotely

• Provide an environment in which enterprise beans can run

• Invisible middlemen

5. EJB Architecture 6. Basic Terminology

CMP Container Managed Persistence

• EJB container takes care of making sure the entity bean object stays around.

BMP Bean Managed Persistence

• You as the bean programmer can take over the responsibility of managing the "persistence" of the data -- of where the data stays when the server is not running or when the bean is not in memory.

7. Requirement Specs

The system will be having 3 roles:

• Instructor

• Student

• Admin

Admin

• Managing user accounts, course registration approval

Instructor

• Login ,Create / Modify course details,set Quizzes , assign grades

Student

• Login, Register / Unregister for courses ,take quizzes , view lectures in offline mode

Non-Functional Requirements

• Open-Source and Freeware

• Support over Internet andIntranet

8. Technology Decisions ClientInternet Server

Client

Integrated Environment

Communication Protocol

Cross firewall

Intranet and Internet support

Server

Transaction

Persistence

Security

Caching

9. Thin v/s Thick Client Speed Web Browser VsJava Client Feature Fast. Can instantly scroll since the client can cache and process data locally. Slow. Everything must wait for the server to process and transmit the next screen of information.

Givesintegrated look and feel. The client executable, installable from web, can bundle all prerequisites.

Java Swing client givessame look and feel across all the platforms (as compared to web browser).

Different Browsers may require different plug-ins to support features such as Video streaming.

Look and feel varies from browser to browser.

Thick Client Thin Client 10. Initial Architecture Diagram

• Specs

• Client-Swing

• Servlet Container- Tomcat3.2

• DB Server- Postgres8.0

Swing Client Servlet Request Processor DB Manager Database 11. Pros and Cons

• Pros

• Simple

• • Simple and Intuitive. Uses HTTP over the internet and simple JDBC to communicate with the database server.

• Light

• • As compared with J2EE server

• Cons

• Plain Http protocol Notype safety

• NocachingSupport

• No Transaction Management Support.

• Absence of DistributedObjects .

12. WebServices ???

RMI offers an order of magnitude better

performance than other alternatives, being at least8.5 times fasterthan Web Services

HTTP-to-servlet is more than4 times slowerthan web services.

Reference :Java RMI, RMI Tunneling and Web Services Comparison and Performance Analysis - Matjaz B. Juric, Bostjan Kezmah, Marjan Hericko, Ivan Rozman, Ivan Vezocnik

13. Why EJBs?

Container inherently provides features such as

• Security

• Transaction Management

• Persistence

• Distributed Object Support that goes well with RMI.

14. CMP vs BMP Lesser Coding JDBC sql queries have to be code. CodingCMP engine handles this Done using dirty flags, but it requires more coding and is error-proneAvoid unnecessary stores CMP BMP 15. Architecture Diagram(The chosen approach) Database SessionBean SessionBean SessionBean SessionBean EntityBean EntityBean EntityBean EntityBean client Session bean 16. Session Facade

Performance

• An Entity bean is equivalent to a row in the database. If the Entity beans were to be accessed directly, anetwork callwould result for each row access.

• On the other hand, a Session bean is equivalent to astored procedure . Accessing a session bean that is co-located with an entity bean emulates accessing a row through a stored procedure.

17. Session Facade

Reusability

• The session bean layer is powerful because itexternalizes all business logicfrom the entity beans. This means the entity beans contain data and data-related logic only.

• This promoteshigh re-useof entity beans.

Data abstraction layer

• The session bean layer is afacade . The particular way the session bean persists (via JDBC directly or via entity beans) is an implementation detail of the session bean. The decision about whether to use JDBC or entity beans can be deferred until a later date.

18. E-R Diagram 19. Object Model 20. Collaboration Diagram - Login 21. Collaboration Diagram - Registration 22. Sequence Diagram - Registration 23. Collaboration Diagram Set Quiz 24. Class Diagram 25. Class Diagram (old & new) 26. Lessons learnt / Challenges faced

1. Familiarity with J2EE

• Studying EJB Architecture (session bean, entity bean concepts)

• BMP vs CMP

• Concept of CMR

• Configuring JBoss 4.0

• Configuring Postgres 8.0 on JBoss

• Serial Primary Key

• Writing Deployment Descriptors

27. Challenge

Trying to synchronize the Intel deadlines with the syslab deadlines throughout this course

28. Deployment Descriptor

course

vclassroom.course.ejb.CourseLocalHome

vclassroom.course.ejb.CourseLocal

vclassroom.course.ejb.CourseBean

Container

False

2.x

course

java.lang.Integer

courseId

courseId

29. Deployment Descriptor

ejbSelectprerequisites

java.lang.Integer

SELECT OBJECT(p) FROM course as c, IN(c.prereqCourses) p

WHERE c.courseId = ?1

30. Technologies / Tools / Methodologies Learnt

J2EE Architecture

• Enterprise Java Beans

JBoss 4.0

Postgres 8.0

EJB-QL

Swing (work in progress)

Patterns Session Faade, Recursive Meta pattern, Chain of responsibility

31. The Timeline

Before MidSem

• Overview of the system requirements from Intel

• Requirement Specification Document prepared and presented to Intel

• Architecture + DesignDocumentation

• Prototype : Demo with the old architecture Login, Registration, Quiz

• Deliverable Client + Server implementation of modules

After Midsem

• Change in architecture Protocol + Server Side

• Learning Curvefor new technology EJBs, J2EE architecture

• Technology survey- Exploring options like JDO, Web Services

• Configurations JBoss 4.0, Postgres 8.0

• Design of new architecture Presentation to Intel

• Detailed Design specificationdocumentation

• Deliverable Server Side coding+documentation Login, Registration, Quiz

32. Thank you !!!!