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Virtual Classroom

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Title: Virtual Classroom

1
Virtual Classroom

Integrated Learning environment over internet
Anshu Veda
Prajakta Kalekar
Shruti Mahambre

2
The Client

This project has been sponsored by Intel
IIT B point of contact
Prof. Umesh Bellur

3
Problem Definition

This project aims at putting together an
integrated e-Learning environment for a
university student.
This will also be used by distance education
programs offered by institutes, in order to
enable students to avail of the academic
facilities from any computer connected to the
internet.

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,
java objects 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 and Intranet

8
Technology Decisions

Client
Integrated Environment

Client

Communication Protocol
Cross firewall
Intranet and Internet support

Internet

Server
Transaction
Persistence
Security
Caching

Server
9
Thin v/s Thick Client
Feature Thin Client Thick Client
Web Browser Vs Java Client Different Browsers may require different plug-ins to support features such as Video streaming. Look and feel varies from browser to browser. Gives integrated look and feel. The client executable, installable from web, can bundle all prerequisites. Java Swing client gives same look and feel across all the platforms (as compared to web browser).
Speed Slow. Everything must wait for the server to process and transmit the next screen of information. Fast. Can instantly scroll since the client can cache and process data locally.
10
Initial Architecture Diagram

Specs
Client- Swing
Servlet Container-Tomcat3.2
DB Server-Postgres8.0

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 No type safety
No caching Support
No Transaction Management Support.
Absence of Distributed Objects.

12
WebServices ???

RMI offers an order of magnitude better
performance than other alternatives, being at
least 8.5 times faster than Web Services
HTTP-to-servlet is more than 4 times slower than
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
BMP CMP
Avoid unnecessary stores Done using dirty flags, but it requires more coding and is error-prone CMP engine handles this
Coding JDBC sql queries have to be code. Lesser Coding
15
Architecture Diagram (The chosen approach)
SessionBean
EntityBean
SessionBean
EntityBean
Database
SessionBean
EntityBean
client
SessionBean
EntityBean
16
Session Facade

Performance
An Entity bean is equivalent to a row in the
database. If the Entity beans were to be accessed
directly, a network call would result for each
row access.
On the other hand, a Session bean is equivalent
to a stored 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 it
externalizes all business logic from the entity
beans. This means the entity beans contain data
and data-related logic only.
This promotes high re-use of entity beans.
Data abstraction layer
The session bean layer is a facade. 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