Hi Karthic,
You have 2 options:
1) a Google Apps Script onEdit() trigger can 'push' data to your webapp
(provided a regular web-user of the sheet made the change)
2) your webapp can 'pull' data from:
a) the 'worksheet' feed, with an If-Modified-Since header to avoid
unnecessary polling of actual data
b) the 'list', 'table/record' feed, or 'cell' feeds to actually grab
information from the sheet
(for your application it would be nice to have an 'updates' feed that took a
timestamp as a query parameter ... I'm sure the Google Spreadsheet GUI has
access to something like this ... but there is nothing public as far as I am
aware).
Which opotions sounds like it would suit your application?
