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Subject: RE: Drools and CAM

	I was hoping that we could use the CAM engine to determine the
agenda by the back door.  I was intending to allow multiple calls to the
engine with different sets of data in the working memory.

	It woud be good to be able to partition the rules without having
to have different files - I presume this is what Modules are for?

	The issue of anonymous facts - If I put two nodes into the
working memory there is no way to distinguish one from the other in
terms of what fires in the rules?  In some ways I do not think this will
be a problem with CAM as the nodes of XML are pretty anonymous in the
way we handle them.

	Can you clear up one simple question.  Can a consequence cause
other rules to fire because of changes it makes? 

Martin Roberts

-----Original Message-----
From: Mark Proctor [mailto:mproctor@codehaus.org] 
Sent: 02 January 2006 18:20
To: Roberts,MME,Martin,XBX R
Cc: david@drrw.info; TANVEER_ASHIQUE@bah.com; cam@lists.oasis-open.org
Subject: Re: Drools and CAM

You might want to take a look at the rule execution part in my
presentation. In Drools 3.0 we will support Clips/Jess style Agenda
Modules, this means you can partition your rules, allowing you to
control which rules can fire and when. For example you might assert data
that causes validation and process rules to both match, but you don't
want the process rules to fire until all the validation rules are
finished - this can be achieved with Modules.

One of the more difficult integration areas, as we have discovered with
jBPM, is that Drools matches fact types, it does not match variable
names. So if you have two Cheese variable instances in your application,
cheddar and stilton, you cannot map your variable names in your
application to variable names in the Drools - you have to instead use
constraints - maybe people have problems understanding this. The best
way of thinking about this is facts are always anonymous when they are
asserted into the rule engine.

Application Data is simply a way to make data available to
conditions/consequences without it having to be asserted or take up
space in the WorkingMemory, no changes to application data will cause
the rule engine to re-evaluate rules.

Other things to think about are stateful and stateless working memories
and how to deal with deep object structures.

Hope that helps for starters.

The downside is Drools 3.0 won't be ready for public use, in beta form,
until some time in february.


martin.me.roberts@bt.com wrote:
> Hi,
>  In JCAM I have built in a mechanism to have DROOLS perform the
DataValidation section of the CAM Spec.  The idea is that by passing in
a set of nodes described by an XPath it would be posible to invoke a
script that would then work with the nodes supplied.
> This is done by describing a Java Class that allows the nodes to be
added to the DROOLS working memory and allow the consequences to
interact with the nodes by changing values etc.
> It seems to work reasonably well and is very simple to implement.
> I am also toying with the idea of using the DROOLS ApplicationData
construct to allow the rules engine to be passed the either the template
or the xmlfile.  This would enable DROOLS to manipulate the complete
tree and possibly transform the output based on the rules.  The other
extension would be to allow the DROOLS to be passed an empty document
that it could use to hang new constructs off based on the rules firing.
> One of the questions I have is what rules might be applied.  Without
some clear examples it if not easy to know how to integrate the tool.
It seems to me that DROOLS could be used in two parts of the CAM
template - DataValidations and External Mappings.
> One further thing I am investigating for jCAM is the use of
PicoContainer as a method to allow the other processors to be included
into the processor.  The idea being that for each section of the CAM
template a processor would be passed three possible things - the XML
file being processed, the Assembly Structure after the Business Rules
hade been applied and the section of the CAM template the applied to the
processor being plugin.  The advantage of this method is that we can get
the whole of the CAM Spec done by different people yet all work with the
same tool.  It also means that somebody can change the default processor
with another without affecting the other bits.  For example if I get the
split right we should be able to allow schema based includes without
disrupting the rest of the tool.
> Happy New Year
> Martin
> ________________________________
> From: Mark Proctor [mailto:mproctor@codehaus.org]
> Sent: Mon 02/01/2006 05:46
> To: David RR Webber (XML)
> Cc: TANVEER_ASHIQUE@bah.com; CAM TC; Roberts,MME,Martin,XBX R
> Subject: Re: Drools and CAM
> Sure no problem, we are always there - just letting you know, in case
you need any help with Drools.
> Mark
> David RR Webber (XML) wrote: 
> 	Mark,
> 	We'll see who it goes.  My time is extremely short this week -
will attend to the PPT first.  Maybe some of the other folks on the list
may want to hop over for a chat....
> 	Thanks, DW
> 		-------- Original Message --------
> 		Subject: Re: Drools and CAM
> 		From: Mark Proctor <mproctor@codehaus.org>
> 		Date: Sun, January 01, 2006 10:38 pm
> 		To: "David Webber (XML)" <david@drrw.info>
<cam@lists.oasis-open.org> <mailto:cam@lists.oasis-open.org> , Martin
> 		Roberts <martin.me.roberts@bt.com>
> 		IRC isn't a list it's a live chat room where you can
talk to me and 
> the other developers - no need to subscribe, just pop in and have a 
> chat :)
> 		Mark
> 		David Webber (XML) wrote: 
> 			Mark,
> 			Your PPT is a great introduction to the world of
rule engines and
> 			methods.
> 			My own background is heavily Prolog - for 15
years.  I missed seeing
> 			constraint based solutioning - but I guess
DROOLS has to leave
> 			somethings to
> 			those old purpose built engines!  And besides
DROOLS could always
> 			collaborate with a Prolog engine as a close
cousin.... ; -)
> 			On to CAM and DROOLS.  I have some PPT slides I
will share during the
> 			week
> 			once I've cleaned them up for external perusal.
> 			Basically the notion is to use the mechanisms in
CAM - that is
> 			essentially a
> 			domain expert agent in XML structures and
metadata - and provide an
> 			interface directly in CAM to DROOLS and back
again.  Then we're adding
> 			the
> 			ability to persist to SQL databases in CAM
directly from the XML source
> 			-
> 			using simple XML syntax based assignment
> 			This should allow people who are not DROOLS
experts - to create a
> 			business-centric solution that quickly handles
basic ebusiness
> 			transactions - while allowing extended rules to
be layered into this -
> 			by
> 			software staff - that handle decreet rules and
tests that are beyond the
> 			scope of the base CAM function set.
> 			This gives people the best of both worlds - a
purpose built business XML
> 			expert agent - coupled to the extensible DROOLS
> 			Your snippet of DROOLS V3 shows that this is all
heading in the right
> 			direction.
> 			We've been experimenting with:
> 			 <as:includeScript location="{url/my.drl}"/>
> 			and
> 			<as:executeScript name="{name.drl}"
> 			as a first pass to provide linkage between the
> 			I am definately interested in discussing this
with the DROOLS community
> 			-
> 			where CAM can provide a pluggable XML handler
toolkit for DROOLS users?
> 			Beyond all this - DROOLS also looks like a good
means to implement a
> 			state
> 			machine for BPSS (and JBOSS driven BPM) as
envisioned in our BCM
> 			architecture work - but we'll solve one problem
at a time here!
> 			I'm a bit allergic to signing up for IRC lists -
my daily bandwidth is
> 			severally constrained already - but we can
definately look at sharing
> 			some
> 			collaboration resources - possibly a wiki area -
where ideas and test
> 			components can be posted..?
> 			Thanks, DW
> 			----- Original Message ----- 
> 			From: "Mark Proctor" <mproctor@codehaus.org>
> 			To: <david@drrw.info> <mailto:david@drrw.info> ;
<TANVEER_ASHIQUE@bah.com> <mailto:TANVEER_ASHIQUE@bah.com> 
> 			Sent: Sunday, January 01, 2006 2:24 PM
> 			Subject: Drools and CAM
> 				David, Tanveer,
> 				GoogleAlert brought your postings to my
attention. We have big plans for
> 				Drools 3.0, which will be available at
the end of Q1 - see the 
> slides at
> http://drools.org/download/attachments/20545/Business+Rules+Engines.pp
> t?version=1
> 				for more details.
> 				In the mean time if there is anything
more we can do to assist or you
> 				just want a general chat, we are always
on the irc server #drools at
> 				irc.codehaus.org - we provide a web
gateway at http://irc.codehaus.org <http://irc.codehaus.org/> 
> 				if you do not want to install an IRC
> 				Mark

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