Infrastructure-Independent Applications Using Haggle

Abstract — Haggle is a software architecture for mobile devices allowing applications to become independent of infrastructure. We demonstrate Haggle operating with existing email clients and web browsers, providing asynchronous delivery using any available communications channel. Examples of benefits are that two users sitting near one another can email each other without any access to the Internet, and their web searches can find web pages located on each others ’ nodes. The demo is based on 802.11, using both AP mode and ad hoc mode as appropriate for each network operation. I. BACKGROUND End user experiences of mobile, many-device computing are often marked by frustration and inconvenience. Users are forced to be highly aware of their connectivity environment, with many applications only working when networking in-frastructure is available. One ubiquitous example is that of two people with laptops sitting next to each other, who cannot email a file they wish to share because infrastructure is either unavailable, not working properly, or too costly. Recent efforts have started to alleviate such problems. The Delay Tolerant Networking (DTN) [2] research group is creating protocols for scenarios where TCP/IP networking is not feasible, such as when there is no contemporaneous end-to-end link or the delays are very long. Networking methods making use of planned or opportunistic node mobility have been discussed, e.g. “message ferries ” [6]. Also, recent sensor network deployments on mobile animals have made use of animal mobility in this way [4]. Our focus is on the scenario of Pocket Switched Net-working [3], which describes the networking environment experienced by the devices carried by mobile users. These devices typically have one or more local networking interfaces (e.g. 802.11, Bluetooth), with which they can exchange data with neighbours. Devices may also have access to the Internet through one or more global connectivities, e.g. through 802.11 or GPRS; these differ in price, bandwidth, and availability. User mobility [1] means that the set of neighbouring devices and the availability of Internet connectivity is dynamic