An
Java EE application server is a concrete implementation of the JSP/Servlet API's.
The highest supported Servlet/JSP API version is to be found in the specs/docs of the appserver used.
The actually used Servlet API version is to be found in the web.xml root declaration.
The JSP version usually goes hand in hand with the servlet version as follows:
Servlet 2.5 uses JSP 2.1
Servlet 2.4 uses JSP 2.0
Servlet 2.3 uses JSP 1.2
Servlet 2.2 uses JSP 1.1
Servlet 2.1 uses JSP 1.0
You can use this diagnosis in a JSP page to find it out programmatically:
Not to mention that you shouldn't be using scriptlets in real world.