Event-driven architectures turn a traditional data-driven application's architecture upside-down. Instead of storing the data and running queries against stored data, Esper allows applications to store queries and run the data through.
This article introduces Esper, a lightweight ESP/CEP engine written in Java.
This Esper tutorial is now available online at OReilly ' ONJava. The tutorial illustrates an airport self-service terminal that we monitor and improve with real-time customer relationship management by using both ESP and CEP capabilities of Esper.
It includes a fully functional yet simple to run bundled application and also includes Eclipse configuration files so that you can start practicing right away (if you are an Eclipse user...).
I hope this will help get those blooming ESP/CEP concepts to mainstream. The tutorial should give you enough ground to understand where we come from and enough details to get started in your own project right away.
If the EPL snips below does not sound familiar to you
select avg(price) from StockTick.win:time(30 sec)
select type, count(*)
from BaseTerminalEvent.win:time(10 minutes)
group by type
output all every 1 minutes
Read it online at ONJava
or read more about Esper