NIAPIU is designed for help people to decrease the bandwidth when software upgrade.
It use bsdiff(http://www.daemonology.net/bsdiff/) as kernel.bsdiff routinely produces binary patches 50-80% smaller than those produced by Xdelta, and 15% smaller than those produced by RTPatch.
In our experience,NIAPIU is VERY useful.Under normal circumstances，it can save more than 90% of the bandwidth.
