This appendix is meant to be a kind of bridge from your skills as a system administrator, which probably include a familiarity with a variety of scripting languages, to give you some familiarity with the Java development side of Tomcat. Since Tomcat specializes in running servlets and JSPs, we discuss what these are in a bit more detail. First, though, we review a variety of network software architectures, so you have a better idea of where servlets and JSPs fit into the big picture of network software development.
Here are four general Java-centric approaches to networked application development. Since almost all web applications need access to a backend database, we also say a few words about how the Java code accesses the database.
—Slow; browser incompatibilities
—Avoids browser problem; performance can be slow due to lack of caching
—Servlets use JDBC; JSPs, if necessary, use the Java Standard Template Library (JSTL)
—Closest to use of mod_perl, PHP, or CGI
—Good general approach
—Claimed to be a good “enterprise"-scale approach (J2EE-style)
Briefly, a servlet is a Java program designed to run in a servlet container (we hope you didn’t catch that circular definition), and a JSP ...