Managing projects - IntelliJ IDEA in Action - page 109

What is a library?
A library is an archive of compiled code that your modules depend on. Such an
archive is typically represented as a JAR file or an expanded JAR in a directory.
Libraries may optionally contain references to source files and API documenta-
tion: Including these references doesn't alter the usage of the library in any way,
but it does add valuable information to the editor during class navigation and
inspection. Examples of libraries include a DBMS vendor's private JDBC driver, or
an open-source XML parser.

4.1.2 Selecting different types of modules

IDEA provides four distinct types of modules, which fall into two categories: basic
Java modules and enterprise Java (or J2EE ) modules. This chapter covers the first
category; we'll reserve discussion of J2EE modules until chapter 11. As a head
start, here's the purpose of each of the available module types shipped with IDEA :

With version 5.0, this list has been expanded. Now there are six types of modules,
roughly categorized into basic/standard Java ( J2SE ) modules, J2EE modules, and
J2ME modules.

Java modules are the simplest module type and represent a basic Java appli-
cation project, whether it's a command-line tool, a Swing application, or a
JAR library. When configuring this type of module, you can specify a set of
Java source paths that will be compiled to a single class folder. We'll discuss
using and configuring this type of module in detail in this chapter. The
basic capabilities of this module are carried over into the web module.

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The web module is an extension of the Java module that adds support for
web applications. In addition to providing the ability to create and build
Java sources, it lets you edit your web application's deployment descriptor,
build and deploy it to your application server, and configure other web
application capabilities. You create a web module for each web application
in your project. Web modules will be discussed in detail in chapter 11.

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An EJB module lets you design and package a collection of Enterprise Java-
Beans. EJB modules will be discussed more fully in chapter 11.

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A J2EE application module is different than the other module types discussed
so far. The J2EE module type is primarily concerned with packaging J2EE
applications for deployment as enterprise archive ( EAR ) files. As such, it
references Web and EJB modules that it packages for deployment.

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