Recent developments in smartphones and mobile devices have brought a tremendous growth in the mobile data communication. The mobile traffic volume is predicted to consume 10.8 Exabytes per month by 2016, 18x increase from that of 2011 [1]. While the next-generation mobile technologies such as Long Term Evolution (LTE) are being aggressively deployed, they are unlikely to catch up with the explosive demands. One promising solution is to opportunistically offload the bandwidth-limited mobile data transfer to the wired Internet via Wi-Fi while using the mobile networks as a backup medium to meet the transfer deadline with delay-tolerant networking (DTN) [2]. However, deploying DTN faces numerous barriers since existing applications do not seamlessly handle network delays and disruptions caused by human mobility.