[rules-users] Stream Mode with Temporal Reasoning and Event Lifecycle Management

[Edson Tirelli]

   Drools also use the 13 temporal operators as "hints", so if you have a
rule:

$a : A()
$b : B( this after[0,3m] $a )

   Drools will know that A's must be held in memory for 3 minutes while B's
will expire immediately. Drools will calculate all possible expiration
offsets based on all used temporal operators.

   In case no expiration offset can be calculated for a given event (i.e.,
no temporal operator was used, no sliding window, no @expires policy,
resulting in expiration offset to be infinity), the event is help in memory
until explicitly retracted.

   Edson

2010/8/23 Tina Vießmann <tviessmann at stud.hs-bremen.de>

>  Hi,
>
> I'm thinking about something. Maybe anyone can tell me.
>
> The Stream Processing Mode of Drools Fusion provides automatic lifecycle
> managment. For my understandings this is based on the sliding windows
> used inside the rule conditions, the @expires metadata and the @delay
> metadata. Am I right so far?
> My questions is now: How are Events handled if non of the things listed
> above are used?
>
> Let's say I've got rules just using the temporal reasoning operators
> inside the rule conditions - no sliding windows at all. I'm also not
> using any of the @expires and @delay metadata. Is it correct than that:
>  - Drools matches the event coming in and the events existing in the
> KnowledgeBase and eventually activates a rule. And after fireAllRules()
> is called the resulting actions are performed and all Events are
> retracted by the automatic lifecycle managment,  because there are no
> hints (like a sliding window) that events will be needed again. (So that
> the knowledge base would be empty again?)
>
> Thanks for any explanations. :)
> Tina
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-- 
  Edson Tirelli
  JBoss Drools Core Development
  JBoss by Red Hat @ www.jboss.com
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