Building a Delay-Tolerant Cloud for Mobile Data

Mobile data usage is on a tremendous rise, due not only to increasing number of users but also to an increase in the number of applications that transfer data over the network. Moreover, applications for sharing, sensing, and collaboration have become more popular, causing significant amounts of data to be generated on devices. Managing this data-- syncing it to the cloud, or with other users or devices --is a crucial and often challenging part of writing mobile apps and services. In spite of plenty of good advice and best practices from OS vendors and network operators, storing and transferring mobile data is fraught with issues. On the one hand, an app developer needs to worry about the semantics of data storage and synchronization, while on the other, about the end-user experience, which maybe impacted by poor and intermittent network connectivity. To address the needs of the app developers and the end-users, we have built Izzy: a platform to rapidly develop and deploy data-centric mobile apps. Izzy provides well-defined and easy to use semantics for accessing local storage and for synchronizing data with a remote, scalable, global store. Izzy also provides global store access to the cloud-resident part of the applications (if any) through a similar server API. Last but not least, Izzy is designed to be frugal: it conserves mobile device resources by applying delay-tolerance and data reduction techniques (message coalescing and compression) across applications on a mobile device. In this paper we present the design of Izzy and our early experiences with using it.