Invoking JSP/servlet from non-request thread?

[Jess Holle]

I want to invoke JSPs/servlets from non-request threads, e.g. to render 
HTML for use in e-mails, etc.

I tried the simple-minded approach (with Tomcat 6.0.18):
       ServletContext  servletContext = MyContextMonitor.getContext(
   "/myContextName" );
       RequestDispatcher  dispatcher =
   servletContext.getRequestDispatcher( "/somePage.jsp" );
       dispatcher.include( new Request( servletContext ), new Response() );

where Request and Response are mock HttpServletRequest and 
HttpServletResponse implementations.  Response's output stream and 
writer are routed to System.out.

I get the dispatcher fine.  I get output if I use 
"/somePropertiesFile.properties" in place of "/somePage.jsp" -- but only 
if I use include(), not forward().  I don't get output for /somePage.jsp 
in either case.

Any ideas?  Anyone /successfully /doing this sort of thing?

Is there an existing library for this that I'm overlooking?  It seems 
really bizarre that for all the time and energy invested in servlet and 
JSP based HTML page generation that there's not a standard bridge to 
using servlets and JSPs from other threads to generate HTML files, 
e-mails, etc.

--
Jess Holle