Question

I want a user to make a post, the data in the post is handled and the request is forwarded to a jsp-page. The jsp-page is sent back to the user but then the server should do a job. This job takes a lot of time so the user shouldn’t wait for it.

protected void doPost(HttpServletRequest request, HttpServletResponse response) {
  //... get posted data ...
  request.getRequestDispatcher("/page.jsp").forward(request, response);
  //do-someting
}

I want the “do-something” to be done after the connection is closed and the user gets the page.jsp. Of course the “do-something” is completely serverside like updating a database etc. So the server keeps working even after the user leaves the page. I tried to flush and close the outputstream in the servlet after the forward to the jsp-page but this results in an exception. Also flushing and closing in the jsp-page results in an exception. How can I do this?

Answer 1

If your job (do-something) is completely independent of what should be displayed in the jsp, then you can use one of the following:

• A timer
• A thread (in a thread pool)
• A more powerful library like Quartz which will give you powerful scheduling capabilities