Computer Science Distinguished Lecture

CS Distinguished Lectures are free and open to everyone.  No registration is required.

Location:  Fred Kaiser Building (2332 Main Mall), Room 2020/2030

Speaker:  Dr. Edward A. Lee, University of California at Berkeley

Title:

Consistency versus Availability in Distributed Systems

Abstract:

Distributed software systems often require consistent shared information. For example, connected vehicles require agreement on access to an intersection before entering the intersection. It is far from trivial, however, how to achieve consistency, or even how to define it rigorously enough to know when it has been achieved. In this talk, I will show how strong and weak forms of consistency can be defined, how software infrastructure can provide reasonable guarantees and efficient implementations, and what are the fundamental costs of achieving consistency that no software system can avoid. Specifically, I will outline the CAL theorem, which quantifies consistency, availability, and latency, and gives an algebraic relation that shows that as latency increases, either availability or consistency or both must decrease. I will describe a coordination language called Lingua Franca that enables programmers to explicitly work with the tradeoffs between these three quantities.