The persistence mechanism for user provided objects is pluggable, based
on a given strategy. The reason for this is some people are happy to
have their objects serialised with the session state, others have their
objects in a DB somewhere and just want a placeholder serialised. This
works for process instance variables and also inserted working memory facts.
Mark
On 20/02/2012 15:29, Mike Melton wrote:
That's odd. We have stateful sessions persisted using the techniques
shown in the documentation you link to, and rehydrated sessions are
fully populated with all facts/events from working memory as expected.
We have the same requirement (sessions must survive a server reboot
100% intact) and we have been quite pleased with the results. The only
things we have to re-establish upon rehydration are globals and event
listeners. We use JPAKnowledgeService.newStatefulKnowledgeSession(..)
to establish new persisted sessions
and JPAKnowledgeService.loadStatefulKnowledgeSession(..) to rehydrate
existing persisted sessions.
I doubt I've been much help to you but perhaps it will help to know
that someone has seen persistence work as advertised.
Mike
2012/2/20 Alberto R. Galdo <arga...@gmail.com <mailto:arga...@gmail.com>>
Hi,
We are using Drools Expert, Fusion, Flow, etc... to build a
complex event processing system and one of our main constraints is
to be fault tolerant. As such, we are using an
StatefulKnowledgeSession and our system involves processes, sets
of rules, events, accumulators, ... . What we need is to be able
to reconstruct a KnowledgeSession in a given state and all our
changes in the knowledgesession need to be persisted at the very
moment a change is detected.
The documentation is sparse in this point (
http://docs.jboss.org/drools/release/5.4.0.Beta2/drools-expert-docs/html/ch04.html#d0e2702
) and what we've seen so far is that our rules are persisted but
no traces of facts or events ... This would be unaceptable for our
product. We need to be able to stop our service at any time and
restore the knowledge session at any time as it was at the moment
of the previous stop.
We have previous experience with JBPM 3 using a persistent
storage to be fault tolerant and it works like a charm, we can
see our processes, process instances, timers, etc... .
Can we get a *full* KnowledgeSession persistence service for
Drools?
Greets,
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