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Abstract

INRIA Projet SOR (Systèmes d'objets répartis, or Distributed Object Systems) studies operating system support for information sharing in large-scale distributed systems. The long-term goals of our research are: (i) distributed garbage collection; (ii) applying distributed systems mechanisms in the large scale. Our targeted application domains are cooperative work in large scale environments (e.g. World-Wide Web) and mobile computing. We seek system-level solutions, i.e. ones that are general, mutually orthogonal, scalable, application-independent and language-independent.

Our current focus is on the three following issues. First, the persistent distributed store (PDS) abstraction supports a simple API that programmers are already familiar with. Shared objects are mapped in memory and then accessed via pointers. Persistent objects are those that are accessible from some persistent root. In the past year we proposed Larchant, a PDS which incorporates a novel garbage collection algorithm. This year we concentrated on three actions: a formal proof of safety and liveness and the refinement of the current prototype of Larchant, a post-compiler that extracts type information directly from compiled code, and a tool that extracts the layout of objects in memory such as to characterize relationship between objects.

Second, we provide an efficient and semantically-correct remote reference mechanism. Our Stub-Scion Pair (SSP) Chains are a fault-tolerant reference mechanism for identifying and accessing (possibly mobile and/or replicated) objects remotely. We now have a modular, robust, efficient implementation of the SSP chains. Attached to the reference management activity is the implementation of a flexible binding protocol, called Hobbes. We also extends the initial mechanism with new protocols to support mobile computing.

Third, in order to provide programmers with systems that really match their needs, we developped CORE, a toolbox of components implementing multiple replication abstractions. CORE allows application programmers to customize the internal policies of the underlying infrastructure. Our initial targets are fragmented object support, coherence management and storage systems.

Finally, we are developping a set of tools to support large scale cooperative work. These include a flexible distributed cache system, a cooperative bookmarks system, and a mobile proxy cache.

Précédent : References Remonter : Projet SOR