Java Reference
In-Depth Information
Java EE provides a platform for developing and deploying
multitiered, distributed applications that are designed to be
maintainable, scalable, and portable. Just as an office building
requires a lot of hidden infrastructure of plumbing, electricity,
and telecommunications, large-scale applications require a
great deal of support infrastructure. This infrastructure
includes database access, transaction support, and security.
Java EE provides that infrastructure and allows you to focus
on your applications.
Building distributed applications allows you to partition the
software into layers of responsibility, or tiers. Distributed
applications are commonly partitioned into three primary
tiers: presentation, business rules, and data access.
Partitioning applications into distinct tiers makes the software
more maintainable and provides opportunities for scaling up
applications as the demand on those applications increases.
Java EE architecture is based on the idea of building
applications around multiple tiers of responsibility. The
application developer creates components, which are hosted
by the Java EE containers. Containers play a central theme in
the Java EE architecture.
Servlets are one type of Java EE web component. They are
Java classes that are hosted within, and invoked by the Java
EE server by requests made to, a web server. These Servlets
respond to those requests by dynamically generating HTML,
which is then returned to the requesting client.
JSPs are very similar in concept to Servlets, but differ in that
the Java code is embedded within an HTML document. The
Java EE server then compiles that HTML document into a
