Guideline: Define Rule Implementation

For the implementation of Guideline and Constraint it is important to consider what should happen when they are violated. Most of the time the action part will rise an exception or a high priority issue.

An important item to note in computation rules is that we need to manage the actual calculation but also if there are rules that are required to be managed prior to those calculations and the rules that are required to manage that are included in terms of the calculation – then the entire rule set needs to be managed not only just the actual computation rule.

Process flow rules are rules that purely direct the movement through a process flow (or workflow, etc.). It may be helpful to distinguish process flow rules from the business logic rules that determine the values of the parameters on which the process flow is directed.

ETL rules, or data transformation rules, are often considered separately from other business rules, although in pattern they are essentially inference rules and computation rules. Data transformation rules, while important to the business, are a side-effect of system implementation rather than a reflection of core business logic per se. For implementation, the decision to use a rule engine for ETL rules should depend on whether the rules are static or dynamic, but also the maturity of the mapping knowledge. We used rule engine to easily implement transformation rules between two data model, and once the environment is more stable, some of those mapping are put back on the code.

To the industry standard we can add some other rule pattern we found in lot of business application:

*Rule Classification*	*Type of application*
*Compliance Rules*	Rules that reject the attempted business transaction. Yes/no result but completed with reason code and explanation
*Compliance Rules*	Underwriting Fraud detection Data and form validation
Rating	Strongly interrelated rules that compute metrics for a complex object model
Rating	Scoring and rating Contracts and allocation Pure calculations on an object providing a final value (or rating).
Correlation	Strongly interrelated rules that correlate information from a set of objects to Compute some complex metrics
Correlation	Billing and cost estimation Complement by inserting information
Stateful	Strongly interrelated rules that correlate events in a stateful way
Stateful	Alarm filtering and correlation Web page navigation GUI customization