6:24 a.m.
If you need all the events that are being generated then you need to have a session
consume all the events that are being generated.
If you can’t change that requirement then you are probably stuffed.
You should explore partitioning your design in different ways. You may not need all the
events generated in which case you could partition it so that different combinations of
events go to different destinations. Alternatively you may be able to partition the logic.
The first step consumes all the events but only has very simple logic to correlate and
reduce the data produced. These correlations could then be farmed out to a stage 2 set of
rules which no longer need the event stream or which now only need a subset of the event
stream.
Thomas
From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On
Behalf Of Neelesh Deo Dani
Sent: 02 August 2011 12:12
To: Rules Users List
Subject: Re: [rules-users] running multiple instance of rule engine
It can be done in single session, if I make sure all the related events always go to a
particular host by partitioning input event stream.
Basically, I'm looking for options in a scenario when the number of input events per
sec is very large and a single instance/ host won't be able to handle the events. In
this case, we need to run multiple instance of rule engine to get the scale.
Thanks,
Neel
--- On Tue, 2/8/11, Wolfgang Laun
<wolfgang.laun@gmail.com<mailto:wolfgang.laun@gmail.com>> wrote:
From: Wolfgang Laun
<wolfgang.laun@gmail.com<mailto:wolfgang.laun@gmail.com>>
Subject: Re: [rules-users] running multiple instance of rule engine
To: "Rules Users List"
<rules-users@lists.jboss.org<mailto:rules-users@lists.jboss.org>>
Date: Tuesday, 2 August, 2011, 4:11 PM
Why don't you do it in a single session?
The overhead created by the procedure you describe is considerable.
And you may run into synchronisation problems such as that the first event has gone to
host A, the second one goes to host B, but A hasn't stored the event yet...
-W
2011/8/2 Neelesh Deo Dani
<neeleshdev@yahoo.co.in</mc/compose?to=neeleshdev(a)yahoo.co.in>>
Following example clarifies the question:
I've Event declaration and rule as follows:
declare Event
@role(event)
@timestamp(datetime)
datetime : Date
name : String
end
rule "Contest"
no-loop
when
$e1 : Event(name == "event1")
$e2 : Event(name == "event2", this after $e1)
then
System.out.println("rule Contest fired");
end
If Event with name "event1" is inserted in the session and after that Event with
name "event2" is inserted in the same session, then the temporal operator
("this after $e1" ) will work fine. But, if these two events are inserted in two
different sessions ( rule engine running on different host), then it won't work.
I'm trying to find a solution for this scenario. One way is to persist the events as
well in datastore and whenever any event comes, insert all the previous events also in the
session (by fetching from datastore). In this example, when event2 comes (to host2), fetch
event1 from datastore and insert it in the session so that temporal operator will work.
Is there any better alternative exists for this scenario?
Thanks,
Neel
--- On Tue, 2/8/11, Abhay B. Chaware
<Abhay.Chaware@kpitcummins.com</mc/compose?to=Abhay.Chaware(a)kpitcummins.com>>
wrote:
What do you expect to happen in the scenario mentioned, assuming you are running only 1
rules session? Whatever you expect to happen in this case ( e.g. latest update wins ), you
will need to implement in your persistence logic If you are using separate rule
engines/instances.
by the way, have you looked at drools grid ? I haven’t used it, but appears to solve a
similar problem that you are trying to – distributed computing.
-abhay
________________________________
From:
rules-users-bounces@lists.jboss.org</mc/compose?to=rules-users-bounces(a)lists.jboss.org>
[mailto:rules-users-bounces@lists.jboss.org</mc/compose?to=rules-users-bounces@lists.jboss.org>]
On Behalf Of Swindells, Thomas
Sent: Tuesday, August 02, 2011 1:47 PM
To: Rules Users List
Subject: Re: [rules-users] running multiple instance of rule engine
I’m not sure I understand the question.
You have two totally independent rule engine on two different servers running with
separate JVMs and sessions.
You happen to share data between the two sessions by updating a database but drools has no
knowledge of that (they are just java objects which happen to exist) and they certainly
aren’t the same object on both servers.
Temporal reasoning and correlation of events will therefore only happen on the facts that
are inserted into that processes working memory – there’s no way it could be any way else
as it only know about itself, there could be 10 or 0 other processes running it won’t know
the difference.
The ideal method is to have an application design where each request is totally
independent from all other requests (other than db state) and therefore you do exactly as
you have described – there is no other state to share. If you have to share state between
them you have a much bigger problem and you probably have to find some other way to
partition up the data into separate blocks.
Thomas
From:
rules-users-bounces@lists.jboss.org</mc/compose?to=rules-users-bounces(a)lists.jboss.org>
[mailto:rules-users-bounces@lists.jboss.org</mc/compose?to=rules-users-bounces@lists.jboss.org>]
On Behalf Of Neelesh Deo Dani
Sent: 02 August 2011 07:42
To: rules-users@lists.jboss.org</mc/compose?to=rules-users(a)lists.jboss.org>
Subject: [rules-users] running multiple instance of rule engine
Hi,
I need a setup where multiple instance of drools rule engine will be running in different
physical hosts. In each host, a web server (API) will be running which will receive an
input event, process it and insert into rule engine (session) for rules execution on the
same host. I'm using external persistent datastore. The objects will be populated from
datastore before inserting into the session. After rule execution if there is any change
in the state of the objects the same will be stored back to the datastore. The datastore
calls are made outside the rule execution.
In this scenario, if an event comes to one host and another event comes to a different
host, how will the temporal reasoning or correlation of events work? What is the
recommended way of deploying multiple instance of rule engine for scalability?
Please help in this regard.
Thanks & Regards,
Neel
________________________________
**************************************************************************************
This message is confidential and intended only for the addressee. If you have received
this message in error, please immediately notify the
postmaster@nds.com</mc/compose?to=postmaster(a)nds.com> and delete it from your system
as well as any copies. The content of e-mails as well as traffic data may be monitored by
NDS for employment and security purposes. To protect the environment please do not print
this e-mail unless necessary.
NDS Limited. Registered Office: One London Road , Staines, Middlesex , TW18 4EX , United
Kingdom . A company registered in England and Wales . Registered no. 3080780. VAT no. GB
603 8808 40-00
**************************************************************************************
This message contains information that may be privileged or confidential and is the
property of the KPIT Cummins Infosystems Ltd. It is intended only for the person to whom
it is addressed. If you are not the intended recipient, you are not authorized to read,
print, retain copy, disseminate, distribute, or use this message or any part thereof. If
you receive this message in error, please notify the sender immediately and delete all
copies of this message. KPIT Cummins Infosystems Ltd. does not accept any liability for
virus infected mails.
-----Inline Attachment Follows-----
_______________________________________________
rules-users mailing list
rules-users@lists.jboss.org<http://mc/compose?to=rules-users@lists.jboss.org>
https://lists.jboss.org/mailman/listinfo/rules-users
_______________________________________________
rules-users mailing list
rules-users@lists.jboss.org</mc/compose?to=rules-users(a)lists.jboss.org>
https://lists.jboss.org/mailman/listinfo/rules-users
-----Inline Attachment Follows-----
_______________________________________________
rules-users mailing list
rules-users@lists.jboss.org</mc/compose?to=rules-users(a)lists.jboss.org>
https://lists.jboss.org/mailman/listinfo/rules-users