Abstract

We present a new specification for distributed data services that trade-off immediate consistency guarantees for improved system availability and efficiency, while ensuring the long-term consistency of the data. An eventualIy-serializable data service maintains the operations requested in a partial order that gravitates over time towards a total order. It provides clear and unambiguous guarantees about the immediate and long-term behavior of the system. To demonstrate its utility, we present an algorithm, based on one of Ladin, Liskov, Shrira, and Ghemawat [12], that implements this specification. Our algorithm provides the interface of the abstract service, and generalizes their algorithm by allowing general operations and greater flexibility in specifying consistency requirements. We also describe how to use this specification as a building block for applications such as directory services.

Citations