Slingshot: Deploying Stateful Services in Wireless Hotspots

Given a sufficiently good network connection, even a handheld computer can run extremely resource-intensive applications by executing the demanding portions on a remote server. At first glance, the increasingly ubiquitous deployment of wireless hotspots seems to offer the connectivity needed for remote execution. However, we show that the backhaul connection from the hotspot to the Internet can be a prohibitive bottleneck for interactive applications. To eliminate this bottleneck, we propose a new architecture, called Slingshot, that replicates remote application state on surrogate computers co-located with wireless access points. The first-class replica of each application executes on a remote server owned by the handheld user; this offers a safe haven for application state in the event of surrogate failure. Slingshot deploys second-class replicas on nearby surrogates to improve application response time. A proxy on the handheld broadcasts each application request to all replicas and returns the first response it receives. We have modified a speech recognizer and a remote desktop to use Slingshot. Our results show that these applications execute 2.6 times faster with Slingshot than with remote execution.