This paper shows how today's complex computing landscape can be  understood in simple terms through a 4-tier model. Each tier represents a  distinct and stable set of design constraints that dominate attention  at that tier. There are typically many alternative implementations of  hardware and software at each tier, but all of them are subject to the  same set of design constraints. We discuss how this simple and compact  framework has explanatory power and predictive value in reasoning about  system design.

Satyanarayanan, M., Gao, W., Lucia, B.
Proceedings of the 20th International Workshop on Mobile Computing Systems and Applications (HotMobile ’19), Santa Cruz, CA, February 2019