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”
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
Client •Integrated Environment
Communication Protocol
Internet •Cross firewall
•Intranet and Internet support
Server
•Transaction
Server
•Persistence
•Security
•Caching
9. Thin v/s Thick Client
Feature Thin Client Thick Client
Web Different Browsers Gives integrated look
Browser may require different and feel. The client
plug-ins to support executable, installable
Vs features such as Video from web, can bundle all
Java streaming. prerequisites.
Look and feel varies Java Swing client gives
Client
from browser to same look and feel across
browser. all the platforms (as
compared to web
browser).
Speed Slow. Everything must Fast. Can instantly scroll
wait for the server to since the client can cache
process and transmit and process data locally.
the next screen of
information.
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
DistributedObject Support that goes
well with RMI.
14. CMP vs BMP
BMP CMP
Avoid Done using dirty CMP engine
unnecessary flags, but it handles this
stores requires more
coding and is
error-prone
Coding JDBC sql queries Lesser Coding
have to be code.
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.
31. The Timeline
Before MidSem
Overview of the system requirements from Intel
Requirement Specification Document – prepared and presented to
Intel
Architecture + Design Documentation
Prototype : Demo – with the old architecture – Login,
Registration, Quiz
Deliverable – Client + Server implementation of modules
After Midsem
Change in architecture – Protocol + Server Side
Learning Curve for 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 specification documentation
Deliverable – Server Side coding + documentation – Login,
Registration, Quiz