I can see some benefits to modeling this way and in this particular
example, your sequence technique looks to be complimentary with the
streaming SQL approach. Unfortunately, current limitations with
streaming SQL languages force us to do some workarounds rather than
simply translating a model like this directly to simple code.

One way to improve this would be to allow for a custom ejection policy
from a window. There are certainly other ways and other potential
syntaxes/languages too.

--H

--- In CEP-Interest@yahoogroups.com, "PatternStorm" <claudi_p@...>
wrote:
>
> Hello all,
>
> very interesting discussion clearly showing the limitations of
> (timed) windows and data streaming/continuous queries approaches to
> CEP. I am with Marc here.
>
> For my part, raising the level of abstraction as suggested by Peter
> and Hans I have uploaded version 1.1 of the file "What is State"
> that now includes the problem that Luis states below as a toy "use
> case" to show how one can take advantage of the appraoch of thinking
> of state as sequences of events to write a platform-independent
> constructive specification of the problem.
>
> You can find discussion and more details of the approach state =
> sequences of events here:
> http://forum.complexevents.com/viewtopic.php?f=13&t=115
>
> As always comments will be more than welcome!
>
> Thank you very much!
>
> Regards,
> PatternStorm
>
> --- In CEP-Interest@yahoogroups.com, "pureza_l" <pureza_l@> wrote:
> >
> > Hi,
> >
> > I have the good old StockTrades stream with two fields: symbol and
> > price. I'm trying to answer the following question "Were Company X
> > stock actions priced above $70 during any moment of the last 5
> minutes?".
> >
> > Unfortunately, using a simple time-based sliding window won't
> work. To
> > see why, imagine there were only two price updates: the first, at
> > 10:54 am stated that stocks were at $71. The second, 2 minutes
> later,
> > notified that the stocks went down to $69. Now imagine that the
> above
> > question was posed at 11:00 am (of the same day). We, humans, know
> > that the answer is "yes" because the price was $71 between 10:54
> and
> > 10:56. But the first event is outside the 5 minutes window and
will
> > thus be ignored by the system.
> >
> > How would you solve this?
> >
> > Thanks,
> >
> > Luís Pureza
> >
>