This chapter looks at the tools and systems used to build applications throughout the rest of the book. I'm assuming that you have some basic familiarity with building Java applications already. You should be familiar with basic object-oriented development, know how to add libraries to your class path, understand TCP/IP and basic networking, and be familiar with basic JSP-based web application development. You don't need to be familiar with Enterprise JavaBeans© (EJB) or other J2EE technologies, such as Java Message Service (JMS).
 Per the official Java documentation, class path (with a space) refers to the concept of a class path, whereas classpath (or CLASSPATH) refers to either a specific instance or the system environment variable. This is an important distinction because a web server or Java application may (or may not) respect other class path declarations (such as a CLASSPATH environment variable).
The sample applications demonstrate the easiest mechanisms for accessing web services. This book isn't concerned with the persistence layer of the application. It's up to you to decide the best mechanism for saving data. You may want to store your data on the filesystem or in a relational database, using any of a variety of APIs such as JDBC or Java Data Objects (JDO).
We will use Java exclusively (specifically, all examples are built and tested on Windows XP Professional, Java Version 1.4.2_03). If you don't already have Java 1.4.2 or later installed, please visit http://java.sun.com/, and download and install the J2SE 1.4 SDK. You may be offered the opportunity to download the NetBeans integrated development environment (IDE) bundled with the SDK; if you don't already have a Java development environment, this is an excellent choice (the free, open source Eclipse, http://www.eclipse.org/, is another excellent, free Java IDE).