Monday, January 28, 2008

Why I prefer to use "event processing" with prefix, infix or suffix - a subjective tour of acronyms

Recently there has been more discussions about terms and acronyms, I am not sure that this is so important issue to spend much time on, but before moving to a more interesting points, I would like to provide some personal thoughts about acronyms in this area.

First, as you can see from the Blog's name, I prefer the term "event processing" with any prefix, infix, or suffix. The reason is that I view it as a name of a discipline and not as trend. Disciplines typically consist of two words: signal processing, information retrieval, machine learning, software engineering etc.. although there are exceptions. Three letter acronyms AKA TLA, are typically not names of core disciplines but of other things - protocols, architectures, trends etc..

Historically, when the first "event processing symposium" (which created EPTS) has been established we needed a name - the original founders were - David Luckham, Roy Schulte, Mark Palmer (from Progress Software) and myself. David, of course, thought that CEP is an appropriate name for the discipline, while Mark proposed ESP - "Event Stream Processing" since he did not like the word "complex" (read further about it). Roy and mysrelf proposed to take the part that both agree "event processing". Both David and Mark were not completely happy, but agreed, thus we advanced with the name "event processing symposium" and used "event processing" ever since.

Getting back to history - I have prefered to use the name "active technologies" being a veteran of the active database community, and although the autonomic computing community adopted the "active" term and had conferences named "active middleware services", this name actually did not get into the main stream, David Luckham used the term "complex event processing" in his famous book that used the term. The term "complex event processing" has ambigious meaning - one interpretation is that this is processing of complex events, where complex event is an event that consists of more than one event (analog to complex object), the other interpretation is that this is complex processing of events. I have started to use the term CEP in 2004 to differentiate such functionaity from "event correlation" in system management since there has been some confusion in IBM around this terms. I also made a modest contribution to get the name CEP known by giving a tutorial in ICWS in July 2004, attended by many people, whose common denominator has been tht they have not heard this term before. Anyhow - there are two school of thoughts around CEP

Interpretation one ("the monolithic approach") : CEP = EP, everything is a subset of CEP.
Interpreation two ("the layered approach") : EP is a collection of technologies, whereas CEP is one of them (a link in the chain). Some people takes the first interpretation, saying that "simple" event processing (whether it is simple event or simple processing) is a subset of complex event processing, the rational behind it that if an engine is capable of doing complex things it is surely capable of doing simple things. Interpreation two comes from Roy Schulte (Gartner) who introduced in December 2005 the following slide:

In this slide Roy Schulte talks about four types of processing (later he realized that the BPM one is of another category) - simple event processing (filter and route), mediate event processing (transform and enrich) and complex event processing (statefull pattern detector). This is consistent with a market view since there are products that do only simple event processing (messaging), other products who do mediated event processing (ESB) and CEP as the next layer as a stateful engine. I think that this approach is liked by those who are putting CEP on top of existing middleware, while the first ("monolithic") approach is liked by those who have stand-alone CEP engine. Anyway - the existence of this two approaches, and the fact that people may not understand that the other person is taking the second interpretation is causing a confusion.

Next acronym has been "event stream processing", the term "data stream manager" has been coined in Stanford in a similar meaning, but with SQL API, and continuing with other academic projects, and some descendent products (Coral8 is a descendent of the Stanford project). When Progress Software acquired Apama, Mark Palmer looked for an alternative word for CEP, since he was in the opinion that customers don't like anything labelled "complex", thus, he borowed the term "stream" although Apama's API is not SQL, and has not much to do with the academic stream projects and introduced the ESP term "Event Stream Processing" (which was dropped later). In response, David Luckham published an article to defend the "complex" word, starting with the words: "some people, I'm told, get scared when they hear the word complex, as in complex event processing.... start with the basic question, is life simple ? most people when asked about it will truthfully answer no...." and the rest you can read yourself. It seems that David has won this battle -- all vendors (including the SQL oriented ones) at some point or another have positioned themselves as CEP vendors, which also created some objections - by people who thought that it is important to diffrentiate between ESP and CEP, some saying that ESP is a subset of CEP, and some that these are completely different focus areas - as I have written before, there are many ways to define subsets of EP functionality, and I did not find any evidence that the one defined by this distinction (totally ordered events vs. partially ordered events) is the important one (in many applications we need both types for different purposes).

What other acronyms have flown around ? - well, Forrester at some point made a distinction between CEP and BEM (Business Event Management) that has been defined as - "a process of capturing real-time business events from multiple source and assigning them to the appropriate decision-maker for resolution based on the business context of the events". I have struggled to understand the distinction - maybe the fact that it deals with simple events, however, when they mention context - determining the context may by itself require CEP.

We, in IBM are using the term IEP (Intelligent Event Processing) to denote stochastic and intelligent reasoning beyond the deterministic pattern detection to CEP; this is consistent with the layer approach, the monolithic approach fans, view IEP as part of CEP.

The new term we heard this week from IBM is BEP (Business Event Processing) and this is intended to define event processing applications in which the business user can control the behaior (i.e. define and modify patterns without the help of a programmer), a topic I also discussed in the past.

Last but not least, some people in the academic community don't like the term "processing" which they think is too elementary and talk about "event-based computing" as the name of the discipline.
After this unusally long postings, my bottom lines are :

(1). The upcoming glossary should provide a consistent taxonomy of terms here - there is still much confusion about the names, and the glossary can be a good reference point,

(2). Personally, I still prefer to talk about types of functions and not about boundaries of names, however, I understand the importance of branding.

(3). I still prefer the name "event processing" without prefix, infix or suffix - and thus continue to use this name.

(4). Hopefully, this is the last posting I am writing on the *-E-P; E-*-P; E-P-* topic - I have more interesting topics to deal with.... more - later.


Tim Bass said...

Hi Opher,

You might want to have that discussion internally with your team members at IBM, because they thought is was an important topic so much they highlighted there idea for BEP in a press release.

I think the dialog on terminology and discussion just as useful and important as all the other topics, BTW.

The "historical context" is mostly insignificant, IMHO.

Yours sincerely, Tim

Opher Etzion said...

Hi Tim.

1. Already discussed it internally - and have brought the interpretation of BEP -- as EP tool that can be authored by business users.
2. The historical context explains why do we have this terminology issue.
3. The issue of terminology is very important and should be discussed - on the specific topic of *-EP I personally thinK that I have said all I know - and from now on everything else will be repeating myself.

Keep Enjoying the good life in Thailand,


Saul Caganoff said...

I recently ran into someone who was scared off by the word "Complex" in CEP. Interesting to hear it is an issue for others. This seems to be some kind of corporate lack of confidence. "we can't handle lets ignore it".


Prasoon said...

Since I couldn't find any contact info/email-id on the site, can I reach Muhl et al, who own to be able to view that site, which requires username/password.

Opher Etzion said...