refreshing a spry xml file from mysql

hello. i am trying to get a dynamic region on a page to refresh from a mysql query. and, get the query to run periodically against the database to check for changes while the user is on the page.

based on searches and reading these two links:

http://labs.adobe.com/technologies/spry/articles/data_set_overview/

http://labs.adobe.com/technologies/spry/samples/utils/query2xml.html

i think i understand how to:

1. create the javascript object

2. bind it to an xml file on the server side

3. create the dynamic region on the html page

4. create an initial xml file with the results of the mysql query to the database

5. force the js object to refresh its view of the xml file from the server periodically

what i can't seem to get to is how to get the xml file itself to keep getting refreshed by re-querying the database to see what has changed in the table every n seconds. do you know how?

thanks in advance.