[Enterprise Extensions only]

What is a business rule?

A business rule is a statement that defines or constrains some aspect of a business by asserting control over some behavior of that business. A business rule officiates over frequently changing business practices, and can come from within the company, or be mandated from outside, typically by regulatory agencies.

At its simplest level, a business rule is little more than a well placed IF/THEN statement that compares a variable against a determined value, and then issues a command when they match.

For example, consider the following business rules:

Example 1:

IF a person is a senior citizen, THEN provide a 5% discount.

In this case, the variable information includes:

Example 2:

IF a person drives more than 150 miles a week to and from work, THEN add $25 to their auto insurance premium.

In this case, the values that might change are:

Example 3:

A bank wants to classify its customers based on their investment (checking, savings, CDs, loans) according to the following business rules:

In this case, the bank would run into long-term problems if these categories were coded into their application data. What would happen if the bank wanted to change the boundaries between each level? Or, what if they decided to add another level in the future, such as platinum? If the rules were internal, they would have to be modified at their every occurrence in the code. This is just one advantage to externalizing rules. For more, see Why externalize rules?.