If you need to get content from your server and want to do it in an efficient way, so try this sample. It will inform only when changes occur on the server side. Simply magic :-)
Download tutorial files:
https://mega.co.nz/#!VlAwQBDK!EDWmshoVImeZk8YKJX83O29Wezga2hVso9v1Pn_oKg4
Link to a video tutorial:
Screenr - srcoley: A Simple Guide to Long Polling in 5 Minutes #nettuts
