UbiFS

Abstract

Most researches for ubiquitous services have been interested in constructing intelligent computing environments in physical spaces such as conference hall, meeting room, home, and campus. In these spaces people are able to share data easily. However, as cooperative works from a distance anywhere and anytime make a social issue, we need a data sharing system for an ubiquitous community that is a group of people with a common interest and purpose in different places like a location-free conference/meeting. In this thesis, we propose UbiFS, a distributed file system for the data sharing of the ubiquitous community, which is not only location-free but also dynamic and has heterogeneous devices. Considering the distributed member of the ubiquitous community, UbiFS is designed for WAN environments. To simply construct a shared data space in the dynamic manner, UbiFS self-organizes an overlay topology of the devices without the static file servers. Moreover our system keeps a flexible overlay topology of the participant devices recognizing the devices``capabilities and current processor workloads. The capabilities includes processor performance, memory/storage capacity, network connectivity, battery power. Each UbiFS device acts as a server or a client according to the device``s capabilities. UbiFS also performs file operations fitted to the capabilities. The powerful devices construct a ring server group with a ring-shaped network topology, and this ring server group provides the data sharing and adapted streaming services to the weak devices working as the clients. The server group manages the whole shared data for the ubiquitous community and guarantees both of availability and consistency. The clients on the feeble devices just access the remote data by using streaming protocols with a content adaptation for fitting the original data to capabilities and preferences of the devices.