Question

I have a Java servlet from which I need to send few notifications to the HTML page before I send the final response (which is a PDF file).

Basically I need to keep the user updating on steps I am performing while generating the PDF for them.

I guess, one way could be set various attributes using HttpSession and have them printed using JS. But I don’t know how to do that dynamically without loading the page again.

Any idea on how can this be done? I am kind of new to JSP and servlets.

Answer 1

There are two ways:

• AJAX polling – you send ajax requests periodically, and the server responds. The page does not get refreshed. Check jQuery for an easy way to make ajax calls

• Comet – that’s an umbrella term for what you are trying to do. Usually it means keeping an open channel with the server. There are many ways to implement comet (including the option above), but in Java, on the server side, there are two things to check:

  • Servlet 3.0 asynchronous support
  • Atmoshphere – chooses the best underlying mechanism provided by the container, which includes the async support above