J2EE Development - Overviewby Reji K Paul (Software Programmer, Excellone Technologies)
The technology of J2EE development is a standard
platform for developing distributed transactional applications,
which provides a component-based approach to the design, development
and deployment of enterprise software applications. It ensures the
high availability, scalability and maintainability of software applications
built over J2EE technology.
The J2EE development platform with its ability
to reuse the components offers a multi-tiered distributed application
model, which provides for XML based data interchange. Along with
serving as a security model it provides flexible transaction control.
The J2EE development platform consists of 3 tiers.
- Client Tier - Contains Web clients and applications client that
are executed by the users. The Web clients consist of dynamic
web pages with various mark up languages and a web browser that
renders the web pages received from the web server. As it is a
thin client, heavy weight operations like queuing the databases,
connecting to legacy web applications etc. are off-loaded to the
enterprise beans executing in the J2EE. Client tier communicates
with the web server over the HTTP protocol using Servlets, JSP
etc. Application Client interactions with a distributed system
can be heavy or lightweight, based on the quantity of business
processing that is performed on the local client.
- Business Tier - The enterprise Java beans, the core component
in Business logic of J2EE applications, solves or meets the needs
of a particular business domain such as banking, retail etc.
- Enterprise Information System Tier (EIS) Consists of enterprise
resources like database systems, legacy applications and ERP applications.
JMS and JNDI are other web related technologies.
JMS (Java Messaging Service) enables software application to interact
with each other transferring messages. JNDI (Naming and Directory
Services) is used to structure items needed to make available to
distributed programs. It facilitates looking up, searching, and
binding features to their clients.
J2EE development has the following plus points
that make it popular in the fast paced world of information technology.
- Portability and scalability.
- Simplicity and long term viability.
- Scalability and legacy integration.
- J2EE is collaborated with leaders throughout the enterprise
software arena.
- Flexibility to implement a wide variety of existing enterprise
systems.
- Encapsulates the layers of functionality in specific types of
components.
The J2EE application model divides enterprise applications into
3 fundamental parts:
- Components, the key focus of application develops while system
vendors implement containers and connectors to conceal complexity
and promote portability.
- Containers intercede between clients and components providing
services transparently to both, including transaction support
and resource pooling.
- Connectors sit beneath the J2EE platform and define the portable
service API has to play in existing enterprise vendor offerings.
They promote flexibility by enabling a variety of implementations
of specific services.
The technology of J2EE development simplifies enterprise
applications by basing them on standardized modular components by
facilitating a complete set of services to those components and
by handling many details of application behavior automatically without
complex programming.
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