[rules-users] Sliding windows and event retraction

[jwillans2]

Any help with the query below would be much appreciated.  I am assuming that
event retraction is not automatic using the pattern below, however I am
trying to come by an approach to ensuring only one event exists on an entry
point at any moment in time.  One thought was that when a rule inserts a new
event, it first retracts the previous event, although I think that a rule
cannot have state and can therefore not maintain a handle to the previously
inserted event?  What would be a good approach to achieving this?

Many thanks,

James


jwillans2 wrote:
> 
> Hello,
> 
> I am using sliding windows in the form:
> 
> Obj(..) over window:length(1) from entry-point EP1
> 
> Where many events are being inserted into EP1.  Reading the documentation
> I expected Drools to infer from the window length that all events on EP1
> apart from the latest one can be retracted, is this correct?  The reason I
> ask is that I am not seeing retraction of events from EP1 when I debug the
> session, and I am see behaviour which suggests the rule is firing against
> old events on the entry point.
> 
> Basically I want to get to simulate that an entry point can only contain
> one event at any point in time and that this event is the latest one to
> arrive.
> 
> Thanks,
> 
> James
> 


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