Supporting Multiple Consistency Models within a Mobility Enabled File System Using a Component Based Framework

Most existing Distributed File Systems (DFSs) implement a single consistency model to maintain one-copy equivalence. The functionality of that consistency model is based on a balance between environmental constraints and the targeted level of consistency. Such systems efficiently maintain consistency while the environmental capabilities remain constant, e.g., presuming uninterrupted connectivity. However, when these characteristics change, the inflexible nature of a single consistency model results in its inability to maintain an expected balance between consistency and constraints. This illustrated with existing implementations of DFSs. GLOMAR is a DFS middleware layer that allows application developers to map their specific consistency models to environmental constraints. As a result, multiple consistency models can be created, with each scoped for a particular application and environmental scenario. This paper outlines important aspects of GLOMAR, detailing its implementation and outlining a number of consistency models.