SYS366 Lecture: Business Rules What is a Business Rule? • “…a statement that defines or constrains some aspect of the business.” • (Software Requirements Development, K. Wiegers, p. 154) CASE STUDY RFERENCE • All information used in this presentation is derived from the following website: http://www.businessrulesgroup.org/first_pa per/br01c3.htm#s3b • EU-Rent's car rental business POLICY • a general statement of direction for an enterprise. –An example of a policy for EU-Rent's car rental business might be: "We only rent cars in legal, roadworthy condition to our customers." BUSINESS RULE STATEMENT • a declarative statement of structure or constraint that the business places upon itself or has placed upon it. – For example, each of the following could be a business rule statement for EU-Rent: – "Cars should be checked on return from each rental, and on transfer between branches." – "If any lights are not working, the bulbs should be replaced. If tires are worn, they should be replaced." – "Under any of the following conditions the car should be scheduled for service or repair: • accumulated mileage since the last service is greater than 5000, • the brakes are not satisfactory, • the exhaust is noisy or emitting fumes, • there is any damage to body work (apart from superficial dents and scratches), lights or glass, • there are any significant fluid leaks." BUSINESS RULE • a statement that defines or constrains some aspect of the business. This must be either a term or fact (described below as a structural assertion), a constraint (described below as an action assertion), or a derivation. It is 'atomic' in that it cannot be broken down or decomposed further into more detailed business rules. If reduced any further, there would be loss of important information about the business. – For example, a business rule for EU-Rent might be: – "A car with accumulated mileage greater than 5000 since its last service must be scheduled for service." Examples • Each order must have a shipping charge • A library customer cannot borrow more than 10 books • If stock drops to below the minimum shelf level then the system generates a purchase order • If a customer purchases between 10 and 20 books, she/he gets a 15% discount • If payment is not received within 30 days of the invoice date then the account is delinquent More Examples • Each movie department must have a producer • Video System: A limit to the number of videos that can be borrow • Scheduling Youth Hockey: A limit to how late into the evening a hockey player of a certain level can play More Examples • Movie Project Management: When a task is completed, the system sends an email notifying all the producers. • An order of less than n items has a specific shipping charge. For each additional n items the shipping charge increases by x. • If the customer has not purchased anything for 18 months, the customer is inactive.
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