J2EE Design Pattern
J2EE Design Pattern
Every design or application has
You should not start an application immediately but plan a solution for the problem. The Solution plan is called a design.
A Good design is very important for successful execution of projects.
When designing and developing different applications, we come across various problems. As a result, we end up finding new solutions for similar problems. To save time and effort, we should keep some proven solution to common problem areas.Such common soltutions are called Design patterns.
why do need to use design patterns?
J2EE design patterns are grouped under five heads:
Client Tier :
This tier represents all device or system clients accessing the system or the application. A client can be a Web browser, a Java or other application, a Java applet, a WAP phone, a network application, or some device introduced in the future. It could even be a batch process.
Presentation Tier :
This tier encapsulates all presentation logic required to service the clients that access the system. The presentation tier intercepts the client requests, provides single sign-on, conducts session management, controls access to business services, constructs the responses, and delivers the responses to the client. Servlets and JSPs reside in this tier. Note that servlets and JSPs are not themselves UI elements, but they produce UI elements.
Business Tier :
This tier provides the business services required by the application clients. The tier contains the business data and business logic. Typically, most business processing for the application is centralized into this tier. It is possible that, due to legacy systems, some business processing may occur in the resource tier. Enterprise bean components are the usual and preferred solution for implementing the business objects in the business tier.
Integration Tier :
This tier is responsible for communicating with external resources and systems such as data stores and legacy applications. The business tier is coupled with the integration tier whenever the business objects require data or services that reside in the resource tier. The components in this tier can use JDBC, J2EE connector technology, or some proprietary middleware to work with the resource tier.
Resource Tier :
This is the tier that contains the business data and external resources such as mainframes and legacy systems, business-to-business (B2B) integration systems, and services such as credit card authorization.
Presentation Tier Patterns
Business Tier Patterns
Integration Tier Patterns