This illustration is taken from Chris Taylor's Blog, where he posted a piece entitled: "There's a technology tsunami hitting the world of commerce". Chris makes distinction between the hype technologies: cloud, analytics, big data, and mobile, and claims that all of them have role in the story of commerce, however the core technologies doing the heavy lifting are: integration, managed file transfer, in-memory data, log file management, event processing and business process.
As for event processing, Chris believes it is the core, and issues the nervous system of the commerce which enables to automate it, as commerce is event driven by nature - buy and sell are events, and so are payments, fairness rules, credit decisions, fraud detection, and management of the commerce system itself.
Note that illustration follows the 4D: detect (channel), derive (pattern detection), decide (decision), do (actions). The "decide" part is not necessarily "IF---THEN" rules, but can also be optimization or another event driven pattern.