Display Records Updated While Updating Database

Question

In my web application, an admin is allowed to login and do a mass update to a table where it could update several thousand records. These records are for when new fields are created and default values are created so that applications for older users are still able to process. Basically all I'm trying to do is display what the current status is of a database update in the form "xxx of yyyyy records updated."
The way it works is that the admin comes to the page, specifies the field to be inserted, and hits the update button. The application goes off to this action class which processes all the updates through JDBC. Once the updates are completed, the JSP is rendered saying how many records were updated. The problem is that this processing can take 15 minutes or more sometimes and we would like to be able to see the progress as it goes. It would be ideal to have it update after every 50 or 100 records are processed.
How can I do this while the action class is still executing?

Answer 1

Carpediem104 wrote:
I had read that thread and unfortunately, it wasn't entirely helpful. We don't use Struts and our action classes work a little bit differently. ... in that it takes only 2 parameters: HttpServletRequest and HttpServletResponse; there are no From objects passed in or action mappingsThen adapt. No one knows your system but you. There are examples in that page, and several links to other pages with several more examples.
Carpediem104 wrote:
. We also avoid using session variables, iframes, and beans. It will be hard to do without session variables.. And why no beans? Are you just talking EJBs or JavaBeans in general?
Carpediem104 wrote:
Perhaps it is still usable and I'm missing something, but I'm leaning more towards using AJAX to execute the action and then using request.setAttribute() every time the transaction is committed. Then I can use javascript to update the HTML.
But a request attribute can store information from one request to the next, which you will need to do to get the working progress.
One idea, provide a hook to the running process in ServletContext with unique keys to identify which process belongs to which update view. Then store the unique key in a cookie or as a URL parameter. Each submit (AJAX or not) use the ID to get the process out of the ServletContext and read the progress from there.
How is this better than a session? It isn't just more work.
The other option would be to use Pushlets. Pushlets use a servlet that never closes the connection to the client to continuously feed data to it. This way, your application would start a process and for doing the work and a Pushlet for displaying the progress. You pass a reference of the Pushlet to the worker and the worker regularly informs the Pushlet of its progress. The Pushlet then sends a javascript line to the client updating the display with new information.
If you Google Pushlets you will learn how to use them.
Edited by: Carpediem104 on Jul 29, 2008 9:19 AM