Computing in cirrus clouds: the challenge of intermittent connectivity

Mobile devices are increasingly being relied on for tasks that go beyond simple connectivity and demand more complex processing. The primary approach in wide use today uses cloud computing resources to off-load the "heavy lifting" to specially designated servers when they are well connected. In reality, a mobile device often encounters, albeit intermittently, many entities capable of lending computational resources. In this work-in-progress paper we first give an overview of this environment, which we call a Cirrus Cloud due to its intermittent connectivity feature, and explain how it provides a spectrum of computational contexts for remote computation in a mobile environment. An ultimately successful system will need to have the flexibility to handle intermittent connectivity and use a mix of options on that spectrum. We investigate two scenarios at the extremes of the spectrum: 1) a scenario where a mobile device experiences intermittent connectivity to a central cloud computing resource, and 2) a scenario where a mobile device off-loads computation to other mobile devices it might meet intermittently. We present preliminary designs, implementations, and evaluations of systems that enable a mobile application to use remote computational resources to speedup computing and conserve energy in these scenarios. The preliminary results show the effectiveness of our systems and demonstrate the potential of computing in Cirrus Clouds.