Quote from Valdis:
I am rather talking about new ATS development concepts than about underlying technology
So you mean simplistically: the ATS algorithm/logic/code working on CEP, being able to work on events in parallel, concurrently and coming to trading decisions via certain rules in combination with those events.
Whatever gives you an trading edge I guess! I'll certainly review this area in more detail.
The ATS framework I have in mind will provide most of the infrastructure (as detailed) in order to achieve this if an ATS required those capabilities e.g. the ATS logic could leverage the scheduler to for timer-based events, the various topics and queues to receive external events such as market data, execution report events, portfolio events, and in combination with a rules engine or programmed logic, trading decisions events could be raised and/or sent to the order queue, all of this happening concurrently etc.
Certainly, market data or onBar() as you put it, is only one stream of events that an ATS might be interested in.
Of course, I could be missing the entire point as CEP and ESP are barely more than acronyms to me at this point.
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Speaking of rules engines, Java aficionado's might be interested in:
JBoss' Rules :
http://labs.jboss.com/portal/jbossrules/?prjlist=false
It used to be Drools before JBoss took it over.