1. 1 BTS330 Business Rules

2. What is a Business Rule? …a business rule is a statement that defines or constrains some aspect of the business. It is intended to assert business structure, or to control or influence the behavior of the business.

3. Types of Business Rules* Facts Constraints Action Enablers Computations Inferences From Software Requirements 2 nd Edition

4. Examples Facts Statements that are true about the business i.e. every order must have a shipping charge i.e. sales tax is not computed on shipping charges Constraints Restrict the actions that the system or its users may perform Usually will include must, must not, may not and only i.e. a library customer cannot borrow more than 10 books i.e. only the first and last 4 digits of a credit card can be displayed on a statement

5. Examples Action Enablers A rule that triggers some activity under specific conditions i.e. if some condition is true then some event takes place i.e. if stock drops to below the minimum shelf level then the system generates a purchase order i.e. generate the monthly sales report at midnight on the last day of the month Computations Computations that are performed using specific mathematical formulas or algorithms i.e. if a customer purchases between 10 and 20 books, she/he gets a 15% discount

6. Examples Inferences If a condition is not met, then action is taken i.e. if payment is not received within 30 days of the invoice date then the account is delinquent

7. More Examples Facts Each movie department must have a producer Constraints Video System: A limit to the number of videos that can be borrowed Scheduling Youth Hockey: A limit to how late into the evening a hockey player of a certain level can play Action Enablers Movie Project Management: When a task is completed, the system sends an email notifying all the producers. Computations An order of less than n items has a specific shipping charge. For each additional n items the shipping charge increases by x. Inferences If the customer has not purchased anything for 18 months, the customer is inactive.

8. Defining Business Rules Where? In the appropriate use case specification How? Depends on type of business rule Tables are the easiest format It might be useful to classify rules by type

9. CASE STUDY REFERENCE *EU-Rent's car rental business (link: http://www.businessrulesgroup.org/first _paper/br01ad.htm ) http://www.businessrulesgroup.org/first _paper/br01ad.htm * Developed by Model Systems Ltd et al

10. CASE STUDY REFERENCE The EU-Rent business: Background: Has 1000 branches in towns in several countries. At each branch, cars (classified by car group) are available for rental. Each branch has a manager and a number of booking clerks who handle rentals.

11. CASE STUDY REFERENCE The EU-Rent business: Rentals Most rentals are by advance reservation. The rental period and the car group are specified at the time of reservation. EU-Rent also accepts immediate ('walk-in') rentals, if cars are available. At the end of each day, cars are assigned to reservations for the following day. If more cars have been requested than are available in a car group at a branch, the branch manager may ask other branches if they have cars they can transfer.

12. CASE STUDY REFERENCE The EU-Rent business: Returns Cars rented from one branch of EU-Rent may be returned to a different branch. The renting branch must ensure that the car has been returned to some branch at the end of the rental period. If a car is returned to a branch other than the one that rented it, ownership of the car is assigned to the new branch.

13. CASE STUDY REFERENCE The EU-Rent business: Servicing EU-Rent also has service depots, each serving several branches. Cars may be booked for maintenance at any time, provided that the service depot has capacity on the day in question. For simplicity, only one booking per car per day is allowed. A rental or service may cover several days.

14. CASE STUDY REFERENCE The EU-Rent business: Customers A customer can have several reservations but only one car rented at a time. EU-Rent keeps records of customers, their rentals, and bad experiences (such as late return, problems with payment, and damage to cars). This information is used to decide whether to approve a rental.

15. 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."

16. BUSINESS RULE STATEMENTS EU Business Rule Examples: Rentals Rentals can be made through a reservation or ‘walk-in’ A customer must be registered to make a reservation If a rental request does not specify a particular car group or model, the default is group A (the lowest-cost group) End date of a rental must be before any scheduled maintenance for a car 10% of a group quota for a branch must be reserved for the next day’s walk-in rentals An upgrade to the next group of car can be made if a customers rental request can not be satisfied An assigned car not picked up 90 minutes after the scheduled pick-up time may be released for a walk-in rental Returns Cars should be checked on return from each rental, and on transfer between branches Vehicles must be returned with a full tank of gas Assessed damages to a car are to be charged to the customers credit card

17. BUSINESS RULE STATEMENTS EU Business Rule Examples: Servicing 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. Customer Can only rent one car at a time Customers may not be permitted to rent if: They returned a vehicle late Did not pay for their rental satisfactorily They have damaged a car Customer must posses a valid driver’s license and be over the age of 25 Customer must acquire insurance