- Application Servers Aren't Difficul
- Application Servers Are Software Platforms
- Application Servers Are Component-Based
- Application Servers Provide Software Interoperability
- Application Servers Have High Levels of Abstraction
- J2EE Is Separate and Distinct from Sun's Application Server
- Application Servers: A Window on the Future of Software
Application Servers Are Component-Based
J2EE applications follow the widely adopted component-oriented approach. They are divided into applications that run either on the client or the server. Clients host applications and applets, whereas servers host Java Servlets, JavaServer Pages, and Enterprise JavaBean (EJB) technology.
The major component file types that can be deployed on application servers are: Web Archive (WAR) and enterprise jar (EAR) files. Client applications are packaged as JAR files. Components can be prepared for deployment on the Sun application server, and much of the preparation is either wizard-assisted or automatic in nature using tools, such as the deploytool, asant, the admin console, and so on.
The component-oriented nature of application server technology is in keeping with this mega trend in the current software engineering culture. Interestingly, the software architecture movement is tending not to use the word component when describing the software elements of a given architecture. Instead, the word element is preferred on the basis that a component is more of a runtime entity. It will be interesting to see whether application server technology acquires more of an architectural slant. For more on this latter topic, see Reference .