Tuesday, November 10, 2009

On the Event-Driven Architecture book

Last in the series of 2009 event related books is the book entitled: "Event-driven architecture - How SOA enables the Real-Time Enterprise". This book was published early this year, and I actually purchased it while visiting the USA earlier this year, and while doing the other book reviews it is a good time to write about this book as well.

The book, unlike the others, does not deal with event processing, it deals with EDA as a central concept, starting with a "working definition": event-driven architecture is one that has the ability to detect events and react intelligently on them. I have some trouble to digest this definition, since in my mind, architectures don't possess abilities. Part I of the book talks about "The Theory of EDA", in which it starts with a second "working systemic definition" saying that EDA is the complete array of architectural elements, including design, planning, technology, organization, and so on, which enables the ability to disseminate event immediately to all interest parties, human or automated. So now this is a definition of architecture for event/message routing, but I already noted that this is not about event processing. Next it goes in depth about the relationships between EDA and SOA, explaining on its way what SOA is. The metaphor used throughout is a nervous system, and this is talking about enterprise nervous systems, the discussion about SOA and related concepts spans over four chapters, ending with some hints of how to calculate ROI of selecting architecture style, but the ROI discussion remains in title levels. The second part of the book goes from theory to practice, in this case they are saying that the products implementing EDA are called ESB (Enterprise Service Bus), and (rightfully) claiming that the main gap in using EDA is that people are not used to think in EDA. However, while they have a chapter called "thinking EDA", its insights of how to "think EDA" stay in a very high level area. Going from the thinking to the examples, the book discusses in big details three examples: Airline flight control, Anti-money laundering, and event-driven productivity infrastructure (under this name there is a description of a framework to connect workflows, E-mail, phone, document repositories, blogs, wikis, social networks and some other stuff).
The book ends after these four example chapters (which actually take more than 50% of the pages), without any conclusion chapter.

It seems that the examples are the essence of the book, and the previous chapters are introduction, the examples also remain in the transport level, and while in one of the example "rule engines" are mentioned as part of the architecture, the book says very little about them.

Looking at the reviews in Amazon, it has polar opinions going from 1 star to 5 starts, I guess that I am somewhere in the middle, for somebody who does not have a clue about what EDA is it provides simple non-technical explanation, and such people found it useful; however, I agree with the 1 star reviewer that it does not really making a convincing story on the sub-title promise - "How SOA enables the real-time enterprise".

This completes my book reviews. We'll see some more books in this area coming in 2010.

1 comment:

swagat said...

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