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 rules.

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 version.

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 next release.


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.






Len Carlsen

Enrolment Services - Student Systems

University of British Columbia

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