Comments on: How Do I Extract Business Rules from Legacy Systems?

By: Roger

Roger — Thu, 01 Nov 2012 14:25:21 +0000

Aaron,
I like your approach to finding business rules and I agree that the idea of a code review is important and the busienss people or BA’s are the key people to identify rules. There is one tool that can help in this process. evolveIT (www.blackboxIT.com) is a mainframe code understanding tool that identifies the interfaces to the business process such as screens, reports and the data containers behind them. Once you have these data containers identified a mainframe analyst can trace the output fields from the screens and reports to identify the specific source code the produces the output. This is called Data Logic Trace and makes the code review much faster since you don’t have to try to find the source code that matters to the output field. This is provided in an XML format that enables you to see only the source code snippits in the order that they execute.

These specific buseinss data traces into the mainframe system make a business rules project much more reasonable to accomplish. The whole project can be better planned since you have the business interfaces defined and can ignore everything that doesn’t impact the business (ie. thousands of lines of code that make up system architecture).

By: Neil Raden

Neil Raden — Wed, 14 Sep 2011 14:57:56 +0000

Bob et al,

In our book, “Smart (Enough) Systems,” James Taylor and I tried to make the case for abstracting business rules from applications for more than programming efficiency. With the right tools, your SME’s can maintain and enhance the rules without having to resort to opening the code. There are many business rules management systems available today, even some pretty good open source ones. Another added advantage is that the business rules engine operates separately from the application(s) it(them)self(ves). This provides the opportunity to stitch together decision management type processes that combine the results of predictive modeling, rules firing and execution as well managing continuous improvement of the rules through things like A/B testing and champion/challenger arrangements.

-NR

There are all some business rules extraction tools that can at least ease the task of unwinding embedded business rules in legacy code. They aren’t perfect, but I think the value the bring is worth it to get started. Of course, you need SME’s and BA’s to curate the stuff as much of it turns out to be irrelevant in a new system anyway, but that depends on the situation.

By: AaronWhittenberger

AaronWhittenberger — Fri, 09 Sep 2011 14:23:37 +0000

Bob, you make some very good points. That entangled mess is what makes ti difficult and time consuming to extract business rules or business logic from legacy system code. That along with years of modification makes one big mess we call “spaghetti code”.

Bennett, thank you for your comments. Good suggestion on validating requirements.

Adrian, good point about extracted business rules no longer being valid for the business and they should be validated and confirmed.

By: Bennett

Bennett — Fri, 09 Sep 2011 13:40:31 +0000

Then there are ‘ business rules ‘ – if they can even be called that – that are rarely if ever executed in the code. These are the ‘ else ‘ buckets that developers have to code to avoid confusing the computer.

By: Adrian Reed

Adrian Reed — Fri, 09 Sep 2011 10:23:22 +0000

Aaron,

You make some very good points!

I agree with your points above. The one thing I would add is that, in my experience, the fact that a business rule exists in a legacy system doesn’t necessarily mean that the rule is correct (or even still valid). In fact, I have worked on projects where business users have been “working around” incorrectly coded business rules for years!

Therefore, I like your suggestion of a two-pronged approach. The addition I would make is that all the “as is” rules that are extracted (either from the system or from interviews/observing users) should be sense-checked and critically reviewed. Ideally, complex business rules should be boiled down to their simplest essence so they are easy to understand and there is no ambiguity.

Kind regards,

Adrian.