This document discusses the key components of the J2EE architecture. It describes how application logic is divided into client-tier, web-tier, and business-tier components that run on different machines. The business tier uses enterprise beans like session beans and entity beans to encapsulate business logic. These components communicate through well-defined J2EE containers that provide runtime services. The web container manages servlets and JSPs, while the EJB container handles enterprise beans and provides services like security and transaction management.

1. J2EE Container & Components
Presented By
Keshab Nath

2. J2EE???
• J2EE defines a standard platform for developing multi-tier
enterprise applications that are highly flexible.
• The Java2 Enterprise Edition(J2EE) provides a distributed
environment for developing, deploying and executing
applications.
• J2EE allows to focus on business logic in the program.

3. J2EE Components
• Application logic is divided into components according to
function, and the various application components.
• There are three kinds of defined components:
- Client-tier components run on the client machine.
- Web-tier components run on the J2EE server.
- Business-tier components run on the J2EE server.
- Enterprise information system (EIS)-tier software runs on
the EIS server.

4. Fig: Multi-tiered Application

5. Client Component
• Application clients and applet clients are components
that run on the client.
• An application client runs on a client machine and
provides a way for users to access the J2EE services.
• A web page received from the web tier can include an
embedded applet. An applet is a small client
application written in Java language that executes in
the Java virtual machine installed in the web browser.

6. Web Component
• J2EE web components are either servlets or pages
created using JSP technology(JSP Pages).
• Servlets are Java programming language classes that
dynamically process requests and construct
responses.
• JSP are server-side programming that accept,store
and search data coming from client application. They
converts to servlets before processing.

7. Business Component
• Business code, which is logic that solves the needs of
a particular business domain such as banking, retail,
or finance, is handled by enterprise beans running in
the business tier.
• Enterprise JavaBeans are server-side, modular, and
reusable components that comprise specific units of
functionality.
• There are three kinds of enterprise beans:
session beans, entity beans, and message-driven
beans.

8. Business Component (contd…)
• Session beans: These may be
either stateful or stateless, and are primarily used to
encapsulate business logic, carry out tasks on behalf of a
client, and act as controllers for other beans.
• Entity beans: An entity bean represents persistent data
stored in one row of a database table. If the client terminates or
if the server shuts down,the underlying services ensure that the
entity bean data is saved.
• Message-driven beans: Message-driven beans listen
asynchronously for Java Message Service (JMS) messages
from any client or component.

9. Enterprise Information System Tier
• The enterprise information system tier handles J2EE
architecture’s connectivity to resources that are not
part of J2EE.
• These include a variety of resources such as
enterprise resource planning(ERP),database systems,
and other legacy information systems.
• This tier provides flexibility.

10. J2EE Container
• The application server maintains control and provides
services through an interface or framework known as
a container.
• J2EE containers provide runtime support for J2EE
application components.
• J2EE application components use the protocols and
methods of the container to access other application
components and services provided by the server.

11. J2EE Container (contd…)
• There are five defined container types in the J2EE
specification.
• Two of these are server-side containers:
An EJB container, A Web container.
• The other two container types are client-side:
An application container, An applet container.

12. Fig: J2EE Containers

13. The web container
• The Web Container is a J2EE container that hosts
web applications.
• Manages the execution of JSP page and servlet
components for J2EE applications.
• Web components and their container run on the J2EE
server.

14. The EJB Container
• The EJB container acts as an interface between an
enterprise bean and the clients.
• Manages the execution of enterprise beans for J2EE
applications.
• Enterprise beans and their container run on the J2EE server.
• The container is responsible for creating the enterprise bean,
binding the enterprise bean to the naming service.
• It provides security by ensuring that only authorized clients
have access to the enterprise bean and its business methods.
• It saves the bean’s state to persistent storage, and activating
or passivating the bean when necessary.

15. Application Client Container
• Manages the execution of application client
containers.
• Application clients and their container run on the
client.

16. Applet container
• Manages the execution of applets.
• It consists of a web browser and Java Plug-in running
on the client together.

17. Thanks