Evolving J2EE specifications continue to provide developers and architects with added performance muscle and flexibility for building and optimizing enterprise applications. J2EE advances are both a boon and a challenge as they can provide additional capabilities while also requiring refined development skills. J2EE applications incorporate complex distributed logic and, hence, demand careful, intelligent, and innovative design and implementation techniques. I'll outline various programming design techniques that empower J2EE developers to create more robust enterprise applications.
A J2EE application is comprised of multiple artifacts, known as Java components, which act like musicians in an orchestra. Each J2EE artifact is required to perform its role, while working in concert with the other components to create the complete J2EE symphony. Developers and architects serve as composers, with the task of ensuring that each component "instrument" plays its assigned notes - without causing performance discord by consuming too many memory resources or failing to deliver its artifact "notes" on queue. The large number of instruments in a J2EE symphony makes it difficult for developers and architects to identify the source of out-of-tune components. J2EE architects and developers, therefore, play a vital role in aligning individual artifacts into powerful and scalable J2EE applications.
The adoption of proven design and implementation techniques can help ensure that J2EE applications are flexible, scalable, and can be used as templates for new projects. The following sections outline best practices that every developer or architect "composer" should use to support successful J2EE implementation.
Choose the Best-Fit Application Architecture
There's no single application architecture that addresses all organizational goals. As such, organizations must use business objectives and end-user requirements as foundation footings for their application infrastructures. An architecture should enable the application to scale gracefully and have the performance to virtually eliminate Mean Time Between Failures (MTBF) and Mean Time To Recovery (MTTR). The architecture should also take advantage of object-oriented (OO) design patterns and principles, which support object scope extensibility and promote reusability, portability, and parsimonious use of computing resources.
Perhaps the biggest question posed by J2EE implementations is the use (or misuse) of Enterprise JavaBeans (EJBs). EJBs constitute a major and complex component of the J2EE specifications and remain a focal point for application server vendors. Many distributed Web applications maintain the state and session information of their clients and connections. It's essential that organizations select a data access methodology - such as direct Java Database Connectivity, Data Access Objects (DAO), or Java Data Objects (JDO) - that addresses both application user requirements and overarching business goals.
