9:44 a.m.
I'm going to be interacting with a KnowledgeBase in a web application. I do
not expect the rules to change during the running of the application. I
will be using StatelessKnowledgeSessions exclusively.
My question is: where is the best place to put the various parts, and what
sort of synchronization do I need to worry about? I did not see any
reference to these issues in the (massive, otherwise excellent) Drools
documentation.
I assume that the best strategy is to:
- Locate the KnowledgeBase in the ServletContext upon startup
- Read in the rule base at startup in a synchronized block (I don't think
the servlet specification guarantees that a ServletContextListener is
thread-safe at startup, but maybe this is overkill)
- During runtime, synchronize on the rule base while acquiring a
StatelessKnowledgeSession from the ServletContext
- Use the acquired StatelessKnowledgeSession freely, without any further
concern for locking (after all, it's stateless, right?)
Could someone please correct me if any of these statements is wrong?
Thanks,
Laird
9:13 a.m.
ljnelson wrote:
My question is: where is the best place to put the various parts, and what
sort of synchronization do I need to worry about? I did not see any
reference to these issues in the (massive, otherwise excellent) Drools
documentation.
Well, OK, that generated a lot of traffic. :-)
Talking to myself here, let's expand this out a bit and say: OK, how would
we do this inside a stateless session bean? I am loathe to write a resource
adapter for Drools.
Given that, and that I'm working with stateless sessions exclusively, I'm
also willing to live with several instances of Drools--i.e. if I create the
engine as an instance variable (or static variable) inside my SLSB, I'm
willing to live with the fact that the container might (probably will)
create several instances of my SLSB, and hence several instances of my rules
engine--they'll all be reading the same rules information so should vend the
same results.
My main question, for the two of you still reading, is around
synchronization: I understand that a StatelessKnowledgeSession is thread
safe, but what about acquiring it? Where else, if anywhere, will I run into
threading issues?
Thanks,
Laird
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9:43 a.m.
Hi Laird,
In our web application we create one KnowledgeAgent and each session calls
getKnowledgeBase to get the KnowledgeBase and then getStatelessSession to
get a session. We have not had any threading issues. I'm pretty sure
that each of those operations are thread-safe.
Hope this helps,
Steve
rules-users-bounces(a)lists.jboss.org wrote on 11/02/2009 09:13:01 AM:
[image removed]
Re: [rules-users] Rookie question: best place to locate
KnowledgeBase in web application?
ljnelson
to:
rules-users
11/02/2009 09:16 AM
Sent by:
rules-users-bounces(a)lists.jboss.org
Please respond to Rules Users List
ljnelson wrote:
>
> My question is: where is the best place to put the various parts, and
what
> sort of synchronization do I need to worry about? I did not see
any
> reference to these issues in the (massive, otherwise excellent) Drools
> documentation.
>
Well, OK, that generated a lot of traffic. :-)
Talking to myself here, let's expand this out a bit and say: OK, how
would
we do this inside a stateless session bean? I am loathe to write a
resource
adapter for Drools.
Given that, and that I'm working with stateless sessions exclusively,
I'm
also willing to live with several instances of Drools--i.e. if I
create
the
engine as an instance variable (or static variable) inside my SLSB,
I'm
willing to live with the fact that the container might (probably will)
create several instances of my SLSB, and hence several instances of my
rules
engine--they'll all be reading the same rules information so
should vend
the
same results.
My main question, for the two of you still reading, is around
synchronization: I understand that a StatelessKnowledgeSession is thread
safe, but what about acquiring it? Where else, if anywhere, will I run
into
threading issues?
Thanks,
Laird
--
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3A-best-place-to-locate-KnowledgeBase-in-web-application--
tp26152111p26157126.html
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9:59 a.m.
I believe acquiring a StatelessKnowledgeSession is thread safe as well.
Many members of the drools dev team are traveling at the moment, hence the slow response.
--- On Mon, 11/2/09, ljnelson <ljnelson(a)gmail.com> wrote:
From: ljnelson <ljnelson(a)gmail.com>
Subject: Re: [rules-users] Rookie question: best place to locate KnowledgeBase in web
application?
To: rules-users(a)lists.jboss.org
Date: Monday, November 2, 2009, 9:13 AM
ljnelson wrote:
>
> My question is: where is the best place to put the
various parts, and what
> sort of synchronization do I need to worry
about? I did not see any
> reference to these issues in the (massive, otherwise
excellent) Drools
> documentation.
>
Well, OK, that generated a lot of traffic. :-)
Talking to myself here, let's expand this out a bit and
say: OK, how would
we do this inside a stateless session bean? I am
loathe to write a resource
adapter for Drools.
Given that, and that I'm working with stateless sessions
exclusively, I'm
also willing to live with several instances of Drools--i.e.
if I create the
engine as an instance variable (or static variable) inside
my SLSB, I'm
willing to live with the fact that the container might
(probably will)
create several instances of my SLSB, and hence several
instances of my rules
engine--they'll all be reading the same rules information
so should vend the
same results.
My main question, for the two of you still reading, is
around
synchronization: I understand that a
StatelessKnowledgeSession is thread
safe, but what about acquiring it? Where else, if
anywhere, will I run into
threading issues?
Thanks,
Laird
--
View this message in context:
http://old.nabble.com/Rookie-question%3A-best-place-to-locate-KnowledgeBa...
Sent from the drools - user mailing list archive at
Nabble.com.
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3 comments
4 participants
participants (4)
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Greg Barton -
Laird Nelson -
ljnelson
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Steve Ronderos