Editing Apache Tomcat (section)

===Jasper===
Jasper is Tomcat's JSP Engine. Jasper [[Parsing|parses]] [[JavaServer Pages|JSP]] files to compile them into Java code as servlets (that can be handled by Catalina). At runtime, Jasper detects changes to JSP files and recompiles them.

As of version 5, Tomcat uses Jasper 2, which is an implementation of the Sun Microsystems' JSP 2.0 specification. From Jasper to Jasper 2, important features were added:
* JSP Tag library pooling – Each tag markup in JSP file is handled by a tag handler class. Tag handler class objects can be pooled and reused in the whole JSP servlet.
* Background JSP compilation – While recompiling modified JSP Java code, the older version is still available for server requests. The older JSP servlet is deleted once the new JSP servlet has finished being recompiled.
* Recompile JSP when included page changes – pages can be inserted and included into a JSP at runtime. The JSP will not only be recompiled with JSP file changes but also with included page changes.
* JDT Java compiler – Jasper 2 can use the Eclipse JDT (Java Development Tools) Java compiler instead of [[Apache Ant|Ant]] and <code>[[javac]]</code>.

Three new components were added with the release of Tomcat 7: