Once the basic industrial-automation environment is modernized, the next step is to optimize the edge with connected platforms that deliver enterprise-class services, including high availability. Often, these edge platforms are linked to the cloud for storing, aggregating and analyzing data produced at the edge. Fog computing can be viewed as the next step in this evolution.

Reference Material

   Microsoft’s AZURE platform is probably a good overall overview to dive into the various components of an IoT solution, from Cloud over Edge to Adapter and Hubs. For a quick (1h30 Youtube video) overview you can find their BUILD 2018 presentation here.