Solutions in this chapter:

• Expression Languages

• Core Tags

• SQL Query Tags

• Internationalization Tags

• XML Support Tags

Introduction

The JSP Standard Tag Library (JSTL) provides a standard tag library (actually several of them) that can be used by JSP writers to handle certain frequent tasks. The JSTL, like much of the WSDP, comes out of the Apache Jakata project; earlier releases of JSTL were available through Apache before it became part of the JCP (and from there, the WSDP).

JSTL is still in its early stages, and is likely to change in the future. If you read this book and are dealing with a later version of JSTL, you may want to check the Syngress website for the latest information and updates.

In particular, the support of expression languages within JSTL is slated to change. Expression languages give JSP developers a mechanism for embedding expressions to be evaluated in the place of constants and are scheduled to be added to the JSP specification itself. JSTL s designers have added a temporary mechanism for using expression languages within JSTL, but have also committed to supporting the JSP standard once it is established.

JSTL consists four libraries and if you get down to it, it s really eight. The four libraries provide XML support, structured language support, SQL support, and internationalization (i18n). Each of these provides a regular and an expression language version, for a total of eight libraries.

Expression Languages

Before we delve into the tag libraries that comprise the JSTL, it behooves us...