Architecture of the Oasis Mobile Shared Virtual Memory System

Oasis is a memory-based storage system designed to support collaborative mobile computing applications. These applications require peer-to-peer and client-server interactions in conditions of less than ideal network connectivity. The architecture is based on a memory model where the address space is logically partitioned into regions used for sharing. Mobile units may disconnect from the backbone, cache portions of the regions, operate, and later reconnect. The backbone is kept strongly consistent, whereas disconnected units operate off local cached copies that have the potential of becoming inconsistent with the backbone. A time-based coherency approach is used for voluntary disconnection that limits inconsistency between disconnected units and the backbone. For inconsistencies that do arise, mechanisms are provided to detect and resolve update conflicts. Oasis also addresses issues of autonomous operation, reliability, and locking. ∗ Supported by a grant from IBM Corporation, the UC Micro program and Computer Marketplace, Inc.