Towards a storage system for connected homes

Homes are increasingly filled with connected devices such as wireless door locks, remotely controllable thermostats, and security cameras. Home automation systems, which used to be prohibitively expensive to average consumers, are now offered at an affordable price, accelerating the adoption of “smart” devices in the home. The advances in devices also enable researchers and practitioners to develop new services and applications for householders—PreHeat uses occupancy sensing to efficiently heat homes [19]; a DigiSwitch display supports elders who reside separately from their caregivers with whom they share sensed activity data in the home [5]; and a Digital Neighbourhood Watch (DNW) is proposed to help neighbors detect suspicious activities (e.g., previously unseen cars driving by several times) in the neighborhood by sharing security camera images [4]. To facilitate such home technology developments, platforms like HomeOS [6] and Mi Casa Verde [1] provide a standard way to communicate with a range of devices and a set of APIs to ease the implementation of applications. However, storage abstraction for applications in the home is not yet clearly defined. For instance, HomeOS exposes local file system APIs to HomeOS applications, but has no built-in support for sharing data with other applications that may run remotely. Commercial devices typically come with a tailored storage solution (e.g., Withings wireless scales transmit data to withings.com by default) and as a result, data from each device is stored in silos, causing a data management nightmare. We first discuss the key requirements for a storage system that supports connected devices and applications in the home. We ground our discussion with the use cases derived from the aforementioned examples—PreHeat, DigiSwitch, and DNW—as well as our own experience of building new applications using various in-home sensors. We then present Bolt, a storage system for data generated by connected devices and applications in the home. Bolt offers a stream based key-value abstraction with support for range queries over time and filtering based on application-specific keys. Bolt stores data on potentially untrusted cloud storage providers while ensuring confidentiality using decentralized access control. Storage policies in Bolt allow applications to prioritize their storage requirements of space, performance, cost, and reliability. After highlighting the key difference between Bolt and prior systems, we finally conclude the paper with a description of our ongoing efforts to build Bolt.