The JBoss Application Server can be downloaded from the JBoss web site at http://www.jboss.org/jbossas/downloads/.
Throughout this book, we will be using JBoss Application Server version 5.0.0.GA. This version is licensed under the LGPL license. Please check and read the license agreement before downloading the software. When downloading JBoss, make sure you download the application server (with a name similar to JBoss-5.0.0.GA.zip) rather than the source code (which has a name similar to JBoss-5.0.0-src.tar.gz). As the application server is written in pure Java, there is only one download for all operating systems. Hence, regardless of whether you are developing on Windows, MaxOS X, or Linux, the download is the same.
After downloading the JBoss Application Server, use your favorite unzipping tool to extract the JBoss Application Server. Once unzipped, you should find the directory structure of the application server to be as shown in the following screenshot.