ABSTRACT
This chapter discusses the concept of edge computing. It begins by noting that some applications require low latency, which prohibits performing computation in a remote cloud data center. The chapter defines the edge approach that places small data centers near the sources of data. It discusses the extension to a hierarchy in which intermediate-sized fog data centers fit between the edge facilities and cloud data centers. The chapter discusses, in addition to computation, how each level of the hierarchy contains storage and how the storage can be used for caching. The chapter uses an example from the automotive industry to illustrate how an edge and fog hierarchy can form a continuum for computing and caching. The chapter also considers how sensors are used in the Industrial Internet of Things (IIoT), and explains why such sensors need edge facilities to meet latency requirements. Finally, the chapter discusses the DDS standard that provides communication among IIoT sensors and software in the hierarchy of edge facilities, fog facilities, and cloud data centers.
