Design Patterns - Basics
by, 11-19-2011 at 07:01 PM (1556 Views)
A design pattern is an abstraction at a very high level. It is to create common and reusable solutions to the recurring problems. Design Patterns provide solutions to design problems which arise again and again in a certain design situations. As a result design patterns have become immensely popular and are very useful to known design issues and problems.
There are several ways to use and implement these design patterns. These implementation details are called strategies.
Many programmers and designers have defined the term design patterns in different ways. Further, they have also divided design patterns in different categories. The important design patterns are:
- Intercepting Filters
- Front Controller
- Service Locater
- Business Delegate
- Transfer Object
The Java or Java EE Design Patterns
As Java and Java EE has become immensely popular a lot of design patterns are developed and are being developed for Java or Java EE. As Java EE it self is an architecture in its own which consists of other architectures as well such as Java Servlets, JavaServer Pages, Enterprise JavaBeans etc., Java EE requires its own design pattern customized for the different types of enterprise applications that the architecture may address.
Lets talk about tiers. Tiers are basically layers. Java EE architecture essentially describes five tiers. A Tier is nothing but a logical division of components in a system. Each tier is loosely held with its adjoining tier. The five tiers Java EE describes are
Design Patterns and Tiers
Intercepting Filter (Presentation tier)
Model-View-Controller (Presentation tier)
Front Controller (Presentation tier)
Service Locater Business tier)
Business Delegate (Business tier)
Transfer Object (Presentation tier)