smart updates and rolling windows

| These are commonly refered to as "event-engines" and now come call 
| themselves, Complex Event Engines:
| 
| The biggest providers are:
| 
| http://www.progress.com/index.ssp
| http://www.coral8.com/                          [this one has a free trial 
| version on the web]
| http://www.streambase.com/
| http://www.aleri.com/

Any comments from past or current users of these?  

Dirk

Three out of two people have difficulties with fractions.