This post will look at how event processing has changed over time. We can identify four major areas of event processing. 'Event' concepts can be found in old operating systems from the late 1950’s. But not event processing

Here are four major areas[4]

• Discrete event simulation
• Computer networks
• Active databases
• Middleware

Discrete event

Event Processing began with discrete event simulation in the 1950's. Each event happened at a time recorded by a clock. Some events could happen at the same time. But the clock would eventually increase its reading by discrete “ticks” representing the progress of real time. Such models were called discrete event simulations. Later some began to see distributed discrete event simulations being run on computing grids. It went for separate story.

In the 1990’s research in automated analysis of event traces followed a new path towards introducing more detail about the behavior of the models into the event traces. The idea was to design a models that precisely simulate and give more detailed information than a simple time ordered event trace. Here was one beginning of Complex Event Processing (CEP).

In 1960's every major manufacturer had its own discrete event simulation language. And various general purpose simulation languages[1] started to appear such as SimPy[2], Arena[3].

Computer networks

Another kind of event processing was involved in the development of computer networks, with the ARPA net. The focus was on making reliable communication between computers across networks by means of events containing sequences of binary data – so called packets.  It was certainly monitoring events in the network.

Active Database

Active Database technology started in the late 1980’s as a development of databases to meet the demands of real time processing. Reactive rule OR ECA (event conditioin action) concept came from here. Active Database languages defined concepts such as composite events, a subclass of complex events, and also temporal constraints.

Middleware
The first middleware company, Teknekron (now Tibco), was founded in 1985. Middleware was researched in the 1970’s. Early on were object request brokers (ORBs), and slightly later, message-oriented middleware (MOM). The publish-subscribe protocol for coordinating requests for service with offers of service was a key paradigm of the MOM movement.

Currently middleware is often synonymous with the concept of an “enterprise service bus” (ESB), application-to-application communications bus. ESBs contain software products for building service oriented architectures (SOA). Marketing hype, is based upon event driven communications at a lower level and supports event driven architectures at the application level.

[1] http://en.wikipedia.org/wiki/Simulation_language
[2] http://simpy.readthedocs.org/en/latest/
[3] Altiok, Tayfur and Benjamin Melamed.Simulation Modeling and Analysis with ARENA. Elsevier, Inc., 2007. ISBN 978-0-12-370523-5
[4] Real Time Intelligence & Complex Event Processing by David Luckham [online : http://www.complexevents.com/ ]