Less code - More rules...
There I said it...Now before condemning me to the pits of hell let me add some context.
In large corporate financial development where systems are comprised of thousands of business rules and run in production for many years... rules, rules, rules are the key... more specifically the management of rules with a Rules engine and/or a BRMS(Business Rule Management System). Now I know, some people love them, some people hate them and some "wrote their own"... personally I think they add a huge amount of benefit when used within the correct context.
I have worked in an environment where we have both successfully and unsuccessfully used a BRMS(Yasutech Quickrules) in implementing countless rules, flows, decision tables over a 5 year period. Unfortunately Quickrules is no longer actively supported, SAP has squished them into SAP Netweaver BRM.
I work in the health insurance industry, and there is a vast amount of analysis, risk management and business rules that go into the "simple" act of getting a stay in hospital paid. What makes it even worse is that these rules change, and they change often, there a constant stream of changes due to legislation changes, overly smart actuaries or overly zealous marketing department announcements. All this creates an environment where there are literally thousands of volitile rules, calculations, scenarios. Now add the fact that large corporate applications like these sometimes live for a decade or more and having business rules spread between code, store procedures, data tables and web pages and you have a recipe for disaster. (These are the systems we fortunately get to rewrite them from time to time.)
Based on my experience over the last couple years; the biggest single benefit of a BRMS is simply "separation of concerns".
What this separation allows for is:
1. Rules to be developed, tested, and possibly even deployed on a different time
line from the application itself.
2. The use of different resources. We managed have both the architect and business analysts define, develop and test rules with very little effort from the developers. I know this is a scary concept, and we only did it after years of having everything in place but with the correct standards, peer review, testing and training it is a possibility.
3. More business involvement and ownership, having the ability to simply let the business owners work with their own spreadsheets and import them directly (into development environment) helped cut down on the red tape and actually made them think about their requirements for a change.
4. More quantifiable delivery segments and estimates for those pesky project managers.
One very important thing to note is that even though rules can be handled separately, they still need to be part of the development and quality processes. After all, the business rules (depending on system) are what it's all about in the end. Most of what we do in these financial corporate application is to facilitate the running of business rules. If anything there should be stricter control and quality assurance on the rules than on the code.
The second thing worth mentioning (which is also actually a by-product of the separation) is visibility of business rules to people that understand them. To be able to print out and sit with either the business analysts or the actual business representatives and visually discuss the flow and structure of the rules proved to be very helpful.
There are of course many other benefits to BRMSs auditing, performance and management, but to me the separation and visibility is were the real value lies.
So with Quickrules gone and with Ilog JRules and Blaze Advisor not available to the common man, I turn to Drools.
Over the next couple weeks I need to spend some time ... Learning to Drool...
On first glace Drools does seem a little daunting, split into :
Drools Guvnor (BRMS/BPMS)
Drools Expert (rule engine)
Drools Flow (process/workflow)
Drools Fusion (event processing/temporal reasoning)
Hopefully there is a simple, quick way to get to grips with it all as I would actually like to run a concurrent proof of concept on my next project to see how it compares.
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