Question

Good evening,

I am in the process of writing a Java Servlet (Struts 2, Tomcat, JSP etc) which is capable of doing some fairly complex simulations. These can take up to 2 minutes to complete on the and will return a graph of the results. It is trivial to calculate the percentage of the simulation completed because the process works by repeating the same calculations 1000s of times.

I would be interested to know if anyone has ever tried to use client side technology to provide any estimate of the percentage complete. I.e query the servlet processing to get the number of cycles completed at various point throughout the simulation. This could then be displayed as a bar in the client browser.

Any thoughts, advice, resources would be much appreciated.

Thanks,

Alex

Answer 1

In your database, have a table to maintain a list of simulations along with their server-calculated progress.

In your web-application, use AJAX to query the server every few seconds (1-20 depending on load is what I’d go with) and update a graphical progress bar. Most javascript libraries have simple timer-based AJAX functions to do exactly this sort of thing.

There’s a few details to figure out, such as whether or not completed simulations remain in the DB (could be useful logging info), but overall, this should be fairly simple.