Friday, December 10, 2010

On the 4Ds -- past version and the proactive version

The climate in Israel this year is quite strange, it is December, and today I still saw people going in the street with short dress, the summer just did not go away.  However, the forecast for the next three days, starting tonight is of a major winter storm (which here means a lot of rain, not snow) and much colder weather, so getting the winter clothes ready.   

Today I've read a blog posting by Jeff Adkins,  one of the people with most practical knowledge about event processing, who relatively recently joined IBM  GBS (Global Business Services).  Jeff blogged about the 4Ds-- detect, derive, decide, do.    These four are part of smart systems that sense and respond, what is known as reactive system.  I knew that this looked familiar, so went back to my archive and found that seven years ago we  were engaged with a project called "active integration"  (the actual application was in the insurance area, but we have generalized the concept), roughly what was known by Gartner as "real-time enterprise".    Here is the original flow from that project:

I don't think it has been original invention, it was a variation of concepts from control theory, but it looks very similar to the 4Ds, with a more detailed granularity.

The first D: Detect spread into two phases on our model: sense and detect, where the sense dealt with instrumentation and sensing of raw events, and detect with a detection of the meaningful situations by pattern detection.

The second D: Derive is the same:  created a derived event (and sometimes also derived data) as a result of this detection

The third D:  Decide is partitioned to three phases:  Analyze - determine the possible alternatives and recommend,  Collaborate - in case of "human in the loop" within the decision, and Decide -- apply some decision procedure to select among the alternatives (simulation, analytic methods, predetermined rules).

The fourth D: Do we called "effect", since it had to effect a running system.  

The loop indicates that the after effecting the system, it feedbacks through its instrumentation mechanism and the sense phase is looking again for things that needs reaction.

I agree that the 4D is much more catchy then our more detailed drawing.

And one comment:  when we did this work, we worked on REACTIVE system - something has occurred, we detect it, and then do something to repair.   This drawing is also a good description of our current project that deal with PROACTIVE systems, but the semantics is somewhat different:  the detection is of predicted undesired states instead of situations that require reaction since something already happened.   

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