System support for transparency and network-aware adaptation in mobile environments
SAC '98 Proceedings of the 1998 ACM symposium on Applied Computing
Dynamically Selecting Optimal Distribution Strategies for Web Documents
IEEE Transactions on Computers
Experience distributing objects in an SMMP OS
ACM Transactions on Computer Systems (TOCS)
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It is now largely agreed that none of the replication protocols that have been proposed over the years suits the needs of all applications. Furthermore, the application requirements may evolve over the time. We argue that replicated objects ought to be adaptable so as to match the application requirements. This paper presents an architecture for adaptable replicated objects. Briefly, this architecture allows the separation of the type-related parts (e.g., concurrency control, or access interface) of a replicated object from the generic ones (e.g.,consistency protocol); it then permits the structuring of the differents parts into components with well-defined interfaces. The generic components do not need to be re-implemented for every replicated object. Instead, a toolbox of predefined objects enforcing well-defined policies (or contracts) is provided. Any programmer can easily adapt his replicated object by simply replacing certain components. Our architecture, while making the replicated object flexible, does not preclude traditional optimisations based on object semantics or on application specifics. We have implemented a programming environment called BOAR-V1 that supports the proposed architecture. The current toolbox contains essentially two generic replication protocols. One enforces the entry-consistency model and the other the write-consistency model. The current toolbox also contains some ready-to-use type-related components (lock manager and access object classes).