Android Question VpnService: creation and control

Hi. there will be some library or example to create a "VPN Service" and control traffic passing through the control. So deny or grant access to internet applications.

As the application: https://play.google.com/store/apps/details?id=com.jianjia.firewall

VpnService
http://developer.android.com/intl/es/reference/android/net/VpnService.html

Thanks !!!