DLS Talk by Edward Lee (Berkeley)

Speaker:  Dr. Edward A. Lee, Professor, 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.

Bio:

Edward A. Lee has been working on embedded software systems for more than 40 years. After studying and working at Yale, MIT, and Bell Labs, he landed at Berkeley, where he is now Professor of the Graduate School in EECS. He is co-founder and Chief Scientist of Xronos Inc. and co-founder and Senior Technical Advisor at BDTI, Inc. He is a founder of the open-source software projects Lingua Franca and Ptolemy and is a coauthor of textbooks on embedded systems, signals and systems, digital communications, and philosophical and social implications of technology. His current research is focused on the Lingua Franca polyglot coordination language for distributed cyber-physical systems.  

Host:  Arpan Gujarati, UBC Computer Science