This paper proposes a system model that unifies different optimistic algorithms
designed for deploying geographically replicated services in a cloud environment.
The proposed model thereby enables a generalized solution (COLOR) by which
well-specified safety and timeliness guarantees are achievable in conjunction with
tunable performance requirements. The proposed solution explicitly takes advantage
of the unique client-cloud interface in specifying how the level of consistency
violation may be bounded, for instance using probabilistic rollbacks or restarts as
parameters. The solution differs from traditional Eventual Consistency models in
that inconsistency is solved concurrently with online client-cloud interactions
over strongly connected networks. We believe that such an approach will bring
clarity to the role and limitations of the ever-popular Eventual Consistency model
in cloud services.