Reusable Tag Library Validator (TLV) classes provided by the JavaServer Pages Standard Tag Library (JSTL).

TLVs allow translation-time validation of the XML view of a JSP page. The TLVs provided by JSTL allow tag library authors to enforce restrictions regarding the use of scripting elements and permitted tag libraries in JSP pages.

For example, any JSP page that imports the tag library with the following Tag Library Descriptor (TLD) file will be restricted to using JSTL tags:

    <?xml version="1.0" encoding="UTF-8" ?>

    <taglib xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
        version="2.1">
      <description>
        Restricts JSP pages to the JSTL tag libraries
      </description>
      <display-name>permittedTaglibs</display-name>
      <tlib-version>1.1</tlib-version>
      <short-name>permittedTaglibs</short-name>
      <uri>http://java.sun.com/jstl/permittedTaglibs</uri>

      <validator>
        <validator-class>
            javax.servlet.jsp.jstl.tlv.PermittedTaglibsTLV
        </validator-class>
        <init-param>
          <description>
            Whitespace-separated list of taglib URIs to permit.
          </description>
          <param-name>permittedTaglibs</param-name>
          <param-value>
            http://java.sun.com/jsp/jstl/core
            http://java.sun.com/jsp/jstl/fmt
            http://java.sun.com/jsp/jstl/sql
            http://java.sun.com/jsp/jstl/xml
          </param-value>
        </init-param>
      </validator>
    </taglib>