Today, Budi walks us through a refresher and brief overview of server JSP programming. Today's portion covers Servlet technologies, including servlets and Tomcat. This excerpt comes from chapter one of JavaServer Faces Programming, by Budi Kurniawan (McGraw-Hill/Osborne, ISBN 0-07-222983-7, 2004).
A deployment descriptor is an XML file, so you can edit it using a text editor. The deployment descriptor for an application compliant with the Servlet 2.3 specification starts with the following:
<?xml version="1.0" encoding="ISO-8859-1"?> <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
These headers indicate that the document type definition (DTD) for this deployment descriptor can be downloaded from http://java.sun.com/dtd/web-app_2_3.dtd. If you open the DTD file, you can see that the root element of a deployment descriptor is web-app. The web-app element can have up to 23 kinds of subelements, as shown here:
All of these subelements are optional, so you are not required to include any of them. The subelements preceding a question mark (?) can appear only once. Those followed by an asterisk (*) can appear many times. Additionally, some of these subelements can have subelements.
Note that in Servlet 2.4, a deployment descriptor is validated against a schema, not a DTD file. However, the elements under web-app are pretty much the same.
Remember: This is part one of the first chapter of JavaServer Faces Programming, by Budi Kurniawan (McGraw-Hill/Osborne, ISBN 0-07-222983). Stay tuned for part 2 of "Overviews of Java Web Technologies," where we learn about JSP, JavaBeans, and Model 2. Buy this book!