Distributed key-value storage systems are widely used in corporations and across the Internet. Our research seeks to greatly expand the application space for key-value storage systems through application-speciï¬c customization. We designed and implemented Comet, an extensible, distributed key-value store. Each Comet node stores a collection of active storage objects (ASOs) that consist of a key, a value, and a set of handlers. Comet handlers run as a result of timers or storage operations, such as get or put, allowing an ASO to take dynamic,
application-speciï¬c actions to customize its behavior. Handlers are written in a simple sandboxed extension language, providing properties of safety and isolation.
We implemented a Comet prototype for the Vuze DHT, deployed Comet nodes on Vuze from PlanetLab, and built and evaluated over a dozen Comet applications. Our experience demonstrates that simple, safe, and restricted extensibility can signiï¬cantly increase the power and range of applications that can run on distributed active storage systems. This approach facilitates the sharing of a single storage system by applications with diverse needs, allowing them to reap the consolidation beneï¬ts inherent in todayâ€™s massive clouds
Previewing this paper from http://www.cs.washington.edu/homes/roxana/acads/projects/vanish/osdi2010comet.pdf