通知用户非市场应用更新的最佳方式？

I'm making a simple bus timetable app for my workplace and people are interested, but I don't want to be mass emailing everyone for simple updates. Right now I'm looking at having an XML file with the latest version info and parsing it on startup then just showing an alertdialog to update but, I can't get my head around getting SAX to work, I might look at the DOM parser but both seem like an overly complicated way to get a single value.I'm making a simple bus timetable app for my wo