An adaptive protocol for implementing causally consistent distributed services

Distributed services that are accessed by widely distributed clients are becoming common place. Such services cannot be provided at the needed level of performance and availability without replicating the service at multiple nodes, and without allowing a relatively weak level of consistency among replicated copies of the state of a service. This paper explores causally consistent distributed services when multiple related services are replicated to meet performance and availability requirements. This consistency criterion is particularly well suited for some distributed services (e.g., cooperative document sharing), and it is attractive because of the efficient implementations allowed by it.