Yes! JSP is extensible. PolyJsp is an extensible JSP implementation designed to support multiple scripting languages and multiple JSP versions. PolyJsp is completely based on XML and XSL and supports Java, Javascript and WebL as scripting languages.
Except JSP directives (<%@ %>), declarations (<% %>), scriptlets (<% %>) and expressions (<%= %>), PolyJsp introduces a few (optional) extensions to JSP :
* A <%@ version="..." > directive
Useful to instruct the parser to use a version other than the default (currently 0.92)
* A <%@ contenttype="..."> directive
Useful for cases in which the expected output MIME type is other than text/html
* A <header name="..." value="...">
Useful to set response headers. Example: set expires to control browser chaching