event Processing for all
In its description of streaming queries,
Julian Hyde’s article “Data in Flight”
(Jan. 2010) included a paragraph on the
relationship between streaming queries
and complex event processing, saying
“CEP has been used within the industry
as a blanket term to describe the entire
field of streaming query systems. This
is regrettable because it has resulted in
a religious war between SQL-based and
non-SQL-based vendors and, in overly
focusing on financial services applica-
tions, has caused other application ar-
eas to be neglected.”
Here, I’d like to offer some perspec-
tive on these three assertions:
On the relationship between event
processing and streaming SQL. Event
processing is a broad term, like data
management and signal processing,
dealing with computing that performs activities on events. A number
of related programming styles are employed in the research community, as
well as in commercial products, for
implementing event-processing applications, including stream-oriented
(based on SQL extensions2 and not
based on SQL extensions1), script languages, and rule-based. The Event Processing Technical Society Language
Analysis Workgroup gave a tutorial on
the languages ( http://www.slideshare.
net/ opher.etzion/debs2009-event-
processing-languages-tutorial) at the
2009 ACM International Conference
on Distributed Event-Based Systems
( http://www.debs.org/2009).
On vendor competition. I have seen
no religious wars over event-processing languages (unlike the classic one
between Lisp and Prolog). Vendors
compete but generally acknowledge
the variety of ways to approach event-processing applications. They also collaborate through the Event Processing
Technical society (http://www.ep-ts.
com/), a consortium including most
vendors in the area, as well as its leading academic people, to investigate
common functions and steps toward a
common modeling language.
On the range of applications. Some
have asserted the field is overly focused
on financial services to the exclusion
all other industries. This might be true
for some of the smaller vendors, but
the field’s major vendors report they
develop applications across a range of
industries, including health care, retail, defense, online games, chemical
and petroleum, social computing, airline management, and car-fleet management. While applications in the
financial services industry were early
adopters, the claim of an overly narrow
focus for the current state of the practice is simply not correct.
opher etzion, haifa, israel
References
1. gedik, b., andrade, h., Wu, k.-l., yu, P.s., and doo, m.
sPade: the system s declarative stream processing
engine. in Proceedings of the SIGMOD Management
of Data Conference (vancouver, b.c., canada, June
9–12). acm Press, new york, 2008, 1123–1134.
2. Jain, n., mishra, s., srinivasan, a., gehrke, J., Widom,
J., balakrishnan, h., çetintemel, u., cherniack, m.,
tibbetts, r., and Zdonik, s.b. towards a streaming sQl
standard. in Proceedings of the 34th International
Conference on Very Large Databases (aukland, new
Zealand, aug. 23–28, 2008), 1379–1390.
author’s Response:
Etzion’s point that the Event Processing
Technical Society offers a range of
approaches to event-processing problems
is well taken. However, in framing the
problem as “event processing,” the Society,
as well as the complex event processing
vendors, fails to address the needs of the
data warehousing/business intelligence
community.
Consider how such a BI practitioner
might see the world: Business events are
embodied as rows in a fact table, and events
are captured in log files or through database
triggers and transformed through an extract
transform load tool or in the target database.
SQL is the lingua franca. This perspective is
different from the event-processing view, an
important distinction because many large,
complex problems are expressed in BI terms
and because many people have BI skills.
BI technologies alone do not adequately
address the needs of this community.
Streaming query systems (such as
SQLstream) allow them to solve important
new problems.
Julian hyde, san Francisco
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