Re: [rules-users] Stream Mode with Temporal Reasoning and Event Lifecycle Management
Thank you, Edson. :)
I've got two more questions about that for now.
The first one is kind of ... ugly.
I know the stream mode needs a time-ordered stream so that the
processing can be done correctly. In my case it can not really be
predicted at which time an event arrives so that the system/application
clock and the timestamp contained in the events are not synchronous.
Let's say that delta-t is the relation between the time a object is send
and received. The send time is reflected by the timestamp of the object
which is referenced using @timestamp. In my case there does no Delta-t
exists that expresses sendTime+Delta-t=receiveTime. Therefore a event A
with ts=10h15m03s10ms can arrive at tr=10h15m04s49ms and a event B with
ts=10h15m17s30ms can arrive at tr=10h15m20s55ms.
If I've got now the rule
$a : A()
$b : B(this after[0,20s] $a)
Will the engine 'count' and wait the 20 seconds for a appropriate event
B? Or how would it work?
The second question is more simple.
If I use
$a : A()
$b : B( this before[0,3m] $a )
How does the engine handle the automatic life cycle managment? Will
every B will be kept for 3 minutes to see if there will be a related A?
Thank you! :)
Tina
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(a)stud.hs-bremen.de
<mailto:tviessmann@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 <http://www.jboss.com>
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