Introduction to the complex event processing engine

There are two terms that are generally used in conjunction; they are Complex Event Processing (CEP) and Event Stream Processing (ESP).

Well, in theory, these are part of a technical paradigm that allow us to build applications with dramatic, real-time analytics over streaming data. They let us process incoming events at a very fast rate and execute SQL-like queries on top of the stream of events to generate real-time histograms. We can assume that CEP is an inversion of traditional databases. In the case of traditional DBMS and RDBMS, we have data stored, and then we run SQL queries over them to arrive at results, while in the case of CEPs, we have the queries predefined or stored and we run the data through them. We can envision this with an example; let's say I am running a department store and I would like to know the highest selling item in the last one hour. So if you look here, the query we are about to execute is pretty fixed in nature...