[rules-users] Is Drools appropriate for this app scenario?

[Jeffrey Schneller]

Yes, the site is pure java.  UI is done with Wicket, DB is done via
hibernate, Rules - drools core and guvnor.

1)  As I said in my original email, the shop owner UI was realized by
excel spreadsheet templates.  The Guvnor allows rules to be written via
an excel file template. Ideally, it would be a GUI based app but the
spreadsheets work and are more cost effective in this case.  The
spreadsheets can also be moved around to different systems [dev, test,
staging, production] and allow rules to be written disconnected from the
web.

2a) not sure what you are asking
2b) We have the following rule types:
	Pricing - computes price for a product based on configuration
	Configuration - rules which tell which option is required,
default values for options, and when a particular option or value is not
available based on other configuration choices
	BOM - based on the configuration generate a BOM
	Presentation - only used to determine how to display the picture
of the configured product. 

All these rules are in our service tier.  The presentation tier knows
nothing about the rules and just knows what to present to the user.

3) Our rules are pretty simple.  A bunch of when clauses and a few
consequence clauses.  There are not too many rules which cause other
rules to fire since we only allow the user to select valid choices in
the UI.  The default value rules do cause a cascade of firing and these
are always run first and only run if a default value needs to be set.

4) We do not use rules for entity metadata definition.  We certainly
could have but we maintain that via a database and a front-end GUI app.


This is not something that can be done in a couple of weeks.  The UI,
rules, etc... took months [and more months] to develop.  There were lots
of refactoring of code and rules to get it right.


Let me know [off-line] if you need more information or want to discuss
specific information.

Jeff




-----Original Message-----
From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Sebastien
Chevalier
Sent: Thursday, January 27, 2011 8:10 AM
To: rules-users at lists.jboss.org
Subject: Re: [rules-users] Is Drools appropriate for this app scenario?


Dear Jeff:

First, thank you very much for your quick reply.

Concerning your StoneSide shop, yes indeed this is pretty much the
functionality that I target, and it is a proof that it works well for a
*web* app. 
If I got it right, you used a pure *server*-centric rules-based
architecture
based on Java, Drools (Expert, Guvnor(?)) and Wicket, right? 

(1) ...But, how did you realize the shop owner UI, the one where (s)he
can
define the rules? Is it a web interface too, probably reusing Guvnor
components, or a separate stand-alone app? 

Relative to the internal architecture: 
(2) Could you please give me some more hints on which arch components
are
working under the covers? 
     -- Especially:

    (2a) Which top-level components are used and which interface type do
they provide?
    (2b) Which rule "types" must be in place?  (please, see next
paragraph
for details)

I suppose that, following a layered architecture, you'll need rules at
every
of the arch layers, most obviously "data/entity based rules" and
"presentation based rules". Less obvious to me is, if actually necessary
(?), the "data-to-presentation mapping mechanism" which extracts facts
from
the data layer and places the required artifacts onto the presentation,
probably having also some rules for injecting custom presentation and/or
collection/storage behavior into the components (i.e., rules in the
controller layer). 

Are these assumptions correct? 

(3) How do your rules (rule types) typically look like, and how work
they
together (map on each other)???

(4) Do you also use rules for "entity metadata definition" (i.e., dyn.
compositions of entity types from predefined property components)? 


I'd really be very grateful for the clarification of these issues and/or
any
further-helping descriptions.
Thank (all of) you very much in advance.

Best regards
   Sebastien

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