Friday, December 26, 2008

Footnotes to Philip Howard's - "Untangling Events"

My employer, IBM, does not allow to transfer vacation days across years, thus, even that I do not celebrate any major holiday this week, I have decided that this is a good time to spend the rest of my vacation days for the year, and takes two weeks off (one of them is already behind me) - spending some time with my children, taking care of some neglected health issues, and also reading books (it is rainy and cold, not a time to wonder around much...). I have looked today a little bit on the Web to see if I have missed something, and found out on David Luckham's site, a reference to Philip Howard from Bloor who writes about - untangling events. I understood that Philip is trying to look at various event-related marketing terms and determine whether there are synonyms, whether there is a distinct market for each... In doing that he is trying to list the various functions done by event processing applications and then gets to the (unsurprising) conclusion that each application does some subset of this functionality. but at the end he admits that he did not get very far and left the question unanswered, promising to dive more into it.

In essence he is right in the conclusion -- all the various functions create some continuum which a specific application may need all or a subset of them. Typically there is a progression - starting from getting the events and disseminate them (pub/sub with some filtering), then advancing to do the same with transformation, aggregation, enrichment etc -- so the dissemination relate to derived events and not just to the raw events, and then advancing to pattern detection to determine what cases need reactions ('situations') and what events should participate in the derived events (yes - I still owe one more posting to formally define derived events).

One can also move above all of these and deal with uncertain events, mine event patterns, or apply decision techniques for routing.

I think that there are multiple dimensions of classification of applications:
  • Based on functionality; as noted above.
  • Based on non-functional requirements -- QOS, scalability in state, event throughput etc,
  • Based on type of developers --- programmers vs. business developers
  • Based on goal of the application --- e.g. diagnostics, observation, real-time action...

There may be more classifications --- the question is whether we can determine a distinct market segments ? probably yes -- with some overlaps. This requires empirical study, and indeed this is one of the targets of the EPTS use-cases working group that is chartered to analyze many different use cases and try to classify them. Conceptually for each type there should be a distinct benchmark that determines its important characteristics.

Still - I think that all the vendors that are going after "event processing" in the large sense will strive to support all functionality. As analog: not all programs requires the rich set of built-in functions that exist in programming languages, but typically languages are not offered for subsets of the functionality. Likewise -- looking at DBMS products, most vendors support the general case. Note that there is some tension between supporting the general case and supporting a specific function in the most efficient way, but I'll leave this topic to when I am blogging in an earlier hour of the day --- happy holidays.

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