Before we start on the technical front, let me tell you about my latest acquisition. I recently went out to purchase a watch. My wife wanted me to buy one of the fancy ones, but I'm more excited by watches that have all the features - stopwatch, backlight, barometer, altimeter, everymeter - and the time displayed in BOLD DIGITAL NUMBERS. I usually end up using maybe three out of a hundred features, but at least I have them.
But I digress. I thought about where I could get the watch. The amazing thing is that you can buy them in nearly every kind of store - superstore, sports store, general merchandise stores, even gas stations. This is just an example of how the market grabs a commodity and merchants make it a part of their standard offering.
The Java application server market is no different. Application servers enable companies to build e-businesses by offering them the tools to do so. They started out by abstracting the interaction with the operating system from the application. Thus they created a new execution environment for industrial-strength distributed applications. The application developers were saved the pain of dealing with low-level system programming details and could concentrate on solving the business problem on hand. As the application server market matured, several of these services became commodity services. The application server vendors embraced standards for the object programming models, transactions, Web access, security, and so on. Consequently, applications developed using application server services became portable across application servers. Java is responsible in a large part for enabling this "cross-appserver" application execution environment. This is because Java provides a virtual platform that is portable across different hardware platforms. Thus Java was used as a base for the object model (EJB) in the application server market. With its penetration into the middleware market, Java has also become the base for defining the APIs for the other app server services mentioned earlier. In fact, the term Web application server is almost synonymous with the term Java application server (Microsoft's application server suite notwithstanding).
The past year has seen a consolidation of several companies that offered different niche services in the app server market. You may have followed this thread of discussion in one of the previous E-Java columns. The current generation of Java application servers offers most of the following environments:
- Integrated development environments (IDEs)
- Scripting support
- J2EE development and execution environments
Existing application server environments allow application developers to develop the business logic for their specific applications. The next stage in the evolution of application servers involves the enhancement of the presentation tier of distributed applications. Scripting using JSPs, ASPs and other similar technologies allows the data generated in the business logic tier to be presented to the users of the application in a format specific to the business the application was built for in the first place. However, scripting is still too low level to completely design the front-end presentation tier. As the demands of the application become more complex, maintaining the content via scripting techniques becomes less manageable. These demands arise as business processes are exposed to the user of the application, and an environment is needed for the user to have a richer interaction with the system. In addition, new requirements arise for the development of reusable components that can be applied to different businesses.
