Carlsen, Len wrote:
I am wondering if anyone has any experience in managing very large
rule sets and facts and could share their experiences in the design
and management of this.
We are embarking on a new Student Information System project here at
UBC in conjunction with several other American universities. We have
pretty much decided to use Drools as our rules engine and maybe also
the Drools BRMS for our business rules management. Our first
application is the course curriculum application/module where we will
manage course co-requisites, pre-requisites, etc. and we estimate that
we will have about 20,000 course rules. We currently have about 15,000
course rules (QuickRules) in production now. We will also have
security rules, input/form validation rules, student awards rules,
degree rules, enrolment rules, admission rules, student financial
rules etc. which will total about 40,000 rules. So currently we are
looking at managing about 60,000 rules (not including versioning). If
we include versioning then there would probably be more than 100,000
We are using jackrabbit JCR, I think it can handle this, but I don't
have any hard figures for the scalability. If it works for you, please
do let us know :)
A single course could have 10 or more rules per course version. We
currently have about 2000 course and most courses have more than 1
We are looking into developing our own rules management system to
define dependencies between rules, courses (facts) and course + rule
versions. E.g. Course CHEM101 version 1 links to CHEM101 a single rule
or a rule set/package version 1 by a rule id.
We need the ability to notify users when rules are modified which
impacts other rules and what impact changing a rule can cause for
example a degree program. E.g. changing a course's pre-requisite may
affect other courses' pre-requisites; rules about rules. We also need
the ability to find out why a student was not able to register for a
course etc. We will also need to show the course dependency graph
visually (the RDBMS can probably help us here). Later, we are hoping
to use the Drools Solver for course and exam scheduling and also to
use it for student degree planning and student awards.
We don't currently have an exposed event model in the BRMS or change
notification. However this would not be hard to add, maybe you could
help us? We have drools-analytics which will create an api with the
change impact requirements you need, it is not yet currently integrated
into the BRMS, bit if you do the notificatino part it should be easy
enough to add.
We will need to translate the rules into English language syntax for
publication in the course calendar and later into other languages
(first French) since the SIS application will be used internationally.
Listing requirements could just be shown in bulleted form. Probably
can't use the DSL in this case since we would need to support several
languages or maybe I am wrong here?
DSL are just a templating language, if can be made to look english like
- if that's what you need. You also have the "docementation" field in
the BRMS, which you can use. If you have other ideas please spec them
out in a JIRA and we'll look inoto doing them in the future, or maybe
you can help us :)
If we use the Drools BRMS to store all of our rules on a relational
database, will we be able to write SQL queries to get at specific
rules/packages to link facts (courses) to rules? Or do we have to go
through the BRMS to get at the rules. Does BRMS have a facility to
validate rules against facts so you can see if your rules execute
correctly against your data/facts before committing your rules. Or
maybe we need a testing framework for this.
We use JackRabbit JCR, we provide high level apis to accessing data, but
you an ofcourse ue the jackrabbit low level apsi - if you really know
what you are doing. We have the ability to validate the compilation of
the rules, scenario testing is currently being added and will be in the
Other issues are the performance of the Drools Solver and having
thousands of rules compiled, loaded and running. During registration
we could have thousands of rules executing concurrently. The rules
engine and the BRMS would be services as part of an SOA infrastructure
(and an OSGi service environment). Anyone got any experience with
Drools in an OSGi environment with respect to class loading issues
when compiling rules and facts from other bundles since rules and
facts may be in different bundles? Bundle buddy class loading?
No but it is something that interests us, please give us your OSGi
feedback. Solver is not currently a supported product, its very much R&D
alphaware, but I'm sure geoffrey would love your feedback, good to see
people are evaluating it.
Later, we will need translators to/from other rule engines; maybe
ruleML and JCR can help us here.
JCR is jus a storage repository, for rule translators you are on your
own. However Drools itself is language independant, we are exposing the
api for pluggeable parsers - so in theory you could write parsers for
each of these.
So far, I think Drools can do most of this; am I correct here? Does
any of this sound plausible?
I'm sure you can get by for now, and work with us to make it the best
system for your needs.
Thanks very much for any tips, thoughts or comments.
Enrolment Services - Student Systems
University of British Columbia
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