Tuesday, May 14, 2013

Why use design patterns in a J2EE application?


􀂃 They have been proven. Patterns reflect the experience and knowledge of developers who have successfully used these patterns in their own work. It lets you leverage the collective experience of the development community.

Example Session facade and value object patterns evolved from performance problems experienced due to
multiple network calls to the EJB tier from the WEB tier. Fast lane reader and Data Access Object patterns
exist for improving database access performance. The flyweight pattern improves application performance
through object reuse (which minimises the overhead such as memory allocation, garbage collection etc).

􀂃 They provide common vocabulary. Patterns provide software designers with a common vocabulary. Ideas
can be conveyed to developers using this common vocabulary and format.

Example Should we use a Data Access Object (DAO)? How about using a Business Delegate? Should we
use Value Objects to reduce network overhead? Etc.

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