Complex Event Processing (CEP) is a buzzword that’s been running around the industry for last couple of years. The concept was introduced by David Luckham of Stanford University who has done over a decade of research in this field. Let’s try to understand some terms that are used frequently in this arena.
An Event is a piece of data that represents that something happened in the real world, or in software system. Events often observe a change in state. e.g. a stock tick or a password change. A linearly ordered sequence of events forms Event Stream. While a partially ordered set of events form Event Cloud. So an event stream could be a cloud but the reverse need not be true.
e.g. Set of all stock trades for GOOG within a 5 minute time window is an Event Stream. While all Stocks sold in a business day is an Event Cloud. And above event stream could be a part of this event cloud.
Aparna Chaudhary Blog 