Case Study Solutions. This appendix contains the solutions to the Acme Mining Company Case Study.

Transcription

1 Case Study Solutions This appendix contains the solutions to the Acme Mining Company Case Study. Sun Proprietary: Internal Use Only 1

2 The Acme Mining Company Rewritten Problem Statement Note The candidate classes and objects have been underlined. The Acme Mining Company requires a computerized payroll system. They need the system to operate on two planets where they currently trade. Planet Earth and the Planet Zog are the locations, each has a differing currency with different tax and deduction policies. Pay is calculated periodically, this is currently monthly and weekly dependant on the pay type of the employee. Currently the pay types are monthly paid, weekly paid and hourly paid employees. Monthly paid employees have an annual salary divided into twelve equal amounts, these are paid at the end of each month. Weekly paid employees are paid their weekly rate of pay at the end of each calendar week. Hourly paid employees have an hourly rate of pay. The hours worked by these employees are determined by a clock in, and clock out time, recorded by a time clock system. The excess hours worked, above the normal site working hours are paid at an overtime rate applicable to their site. The majority of Acme employees are hourly paid. The time clock information for hourly employees can be downloaded directly from the time clock. This must be done once every 24 hours. Employees are identified by their name and their employee identification number only. Weekly paid and hourly paid employees can elect to be paid in cash or by check. Monthly paid employees can only be paid by cheque. All payments are paid in the local currency applicable to the planet. 2 Object-Oriented Application Analysis and Design for Java Technology (UML)

3 These are currently, on Planet Earth, Earth Dollars and on Planet Zog, Zog Groats. Pay is calculated by applying any tax deductions (that apply to the location) to every employee and company deductions that apply to an employee. Taxes are cumulative for the financial year. The Planet and Country taxes are paid on the gross salary at tiered rates. The Social Security and Pollution taxes are paid on the gross salary and are at a fixed rate. Other deductions applicable are for Health Insurance, which is optional. The Pension Scheme however, is compulsory for all employees. Pensions are deducted at a flat percentage rate. Pay rates and employee details can only be recorded and amended by Human Resources. Weekly and Monthly Payroll runs are both initiated by the payroll clerk, it produces payslips itemizing the amount paid and any deductions made to each employee. It produces a summarized list of payments and deductions made to each employee for each run. This summary shows total deductions collected from all employees for each deduction and tax. After the end of the tax year the Payroll Clerk will request a summary of tax paid by all employees for that tax year. Current Taxes Applicable: Planet Tax, Country Tax, Pollution Tax, and Social Security Tax. Planet Earth Taxes: Pollution Tax, Planet Tax, and Country Tax. Planet Zog Taxes: Planet Tax, and Social Security Tax. Case Study Solutions 3

4 Data Dictionary Word/Phrase Payroll Run Definition Manually initiated request for calculations of pay and deductions for each employee applicable to specific run. Monthly Payroll Run Weekly Payroll Run Employee I.D. Number Zog Groats Earth Dollars Time Clock Monthly Employee Hourly Employee Taxation Payroll Run only applicable for monthly employees. Payroll Run only applicable for weekly and hourly employees A number uniquely identifies the employee within the company Currency applicable to Planet Zog Currency applicable to Planet Earth A System which records time for commencement and completion of employees work hours. Data is stored, it can be printed or downloaded to another system. Paid on a monthly basis, dividing the payments into twelve equal installments Paid by hourly rate for each hour worked according to the specific rate allocated to the individual employee. Subject to overtime payment for additional hours worked at company and location rate. Tax deductions applied on gross earning. It is a banding system, where tax is paid at a specified rate for earnings up to a band limit. Any income in that band is taxed in the next band, so forth. 4 Object-Oriented Application Analysis and Design for Java Technology (UML)

5 Word/Phrase Tiered Rate Tax Percentage Rate Deduction Flat Rate Tax Definition A deduction that is applied at the specified percentage rate on gross earnings. A fixed amount deducted at every pay period. Case Study Solutions 5

6 Use Case 6 Object-Oriented Application Analysis and Design for Java Technology (UML)

7 Use Case Scenarios Monthly Run Scenario I 1. The Payroll Clerk on the Planet Zog selects a Payroll Run. 2. They select the monthly run from the options. 3. All monthly paid employees are selected. 4. The first employee is selected. 5. Their monthly pay is calculated. 6. Their gross pay to date is calculated. 7. Planet Tax is calculated. 8. Social Security Tax is calculated. 9. Pension deduction is calculated. 10. This employee has the health insurance option, so this is calculated. 11. The net pay is calculated. 12. The payslip is printed. 13. All deductions are accumulated. 14. Next Employee is selected, 15. All as above, exception this employee has no Health Insurance 16. No more employees 17. Print total deductions. Case Study Solutions 7

8 Monthly Run Scenario 2 1. The Payroll Clerk on the Planet Zog selects a Payroll Run. 2. They select the monthly run from the options. 3. All monthly paid employees are selected. 4. No Employees found. 8 Object-Oriented Application Analysis and Design for Java Technology (UML)

9 Add Employee Scenario 1 1. Human Resources on the planet Zog log on to the system. 2. They select enter new employee from the menu 3. New Employee Screen Displayed. 4. The enter employee John Simms for the name and 1023 for the employeeid. 5. System check for identical ID, none found. 6. Further details are requested. 7. They choose the monthly pay type form menu. 8. They are asked to enter monthly salary in Zog Groats. 9. They enter The are asked to enter starting date. 11. They enter 03/05/ They are asked if the employee requires the Health Insurance option. 13. They select Yes. 14. Employee Details are added to the system. Case Study Solutions 9

10 Add Employee Scenario 2 1. Human Resources on the planet Zog log on to the system. 2. They select enter new employee from the menu 3. New Employee Screen Displayed. 4. The enter employee Peter Smithy for the name and 101 for the employed 5. System checks for identical ID. 6. Identical ID found 7. User requested to enter ID again. 10 Object-Oriented Application Analysis and Design for Java Technology (UML)

11 Use Case Forms Use Case Form: Monthly Run Name Monthly Run Actor Priority Status Extension Points Extends Includes Preconditions/ Assumptions Postconditions Flow of Events Alternative Paths payroll Clerk/Human Resources Low To be agreed None None Payroll Run Non-functional Requirements Performance Frequency Notes 1. Use Case begins when initiated by actor 2. Employees of Type Monthly are selected 3. Include (Payroll Run) Monthly Case Study Solutions 11

12 Use Case Form: Weekly Run Name Weekly Run Actor Priority Status Extension Points Extends Includes Preconditions/ Assumptions Postconditions Payroll Clerk High To be agreed None None Payroll Run Flow of Events 1. Use Case begins when initiated by actor Alternative Paths Non-functional Requirements Performance 2. Employees of Type, Hourly are selected. 3. Employee of Type, Weekly are added include (Payroll Run) Frequency Notes Weekly 12 Object-Oriented Application Analysis and Design for Java Technology (UML)

13 Use Case Form: Find Employee Name Find Employee Actor Priority Status Extension Points Extends Includes Preconditions/ Assumptions Postconditions Flow of Events payroll Clerk/Human Resources High To be agreed None None Has access to I.D. or name Makes available Employee Found 1.Search for Employee Requested. 2.If no Employee Found [A1] 3.Make Employee found available. Alternative Report Employee Not Found Paths Non-functional Requirements Performance Frequency Notes Case Study Solutions 13

14 Use Case Form: Payroll Run Name Actor Priority Status Extension Points Extends Includes Preconditions/ Assumptions Postconditions Payroll Run Payroll Clerk, Payroll Printer High To be agreed None None None Calling Use Case has selected a list of Employees for Processing record of each Employee s Payslip is recorded 14 Object-Oriented Application Analysis and Design for Java Technology (UML)

15 Name Payroll Run Flow of Events 1. The use Case begins during the Weekly Run or Monthly Run Use Case Alternative Paths Non-functional Requirements Performance Frequency Notes 2. For each Employee in list provided by calling Use Case a) Create new payslip b) For each Tax, Company Deduction i) Calculate deduction to be made ii) Add deduction to payslip iii) Add deduction to running total c) Print payslip d) Save payslip 3. For each deduction Print accumulated total Not an issue. Treat as Batch Monthly, Weekly Reliability is Important Case Study Solutions 15

16 Candidate Object List Candidate Class/ Objects Reason for Elimination Class name Acme employees Acme Mining Company Synonymfor Employee Outside of the system amount paid Attribute Payslip annual salary Attribute Monthly Paid employee check Attribute Employee value clock in time Attribute TimeClockData clock out time Attribute TimeClockData company deductions Attribute Deduction country tax CountryTax currency Attribute Location deduction Attribute Payslip deduction policies Method Earth Dollars employee Value of currency attribute Employee 16 Object-Oriented Application Analysis and Design for Java Technology (UML)

17 Candidate Class/ Objects employee details employee identification number Reason for Elimination Synomynfor Employee Attribute Class name Employee employee type Attribute or class EmployeeType excess hours worked Derived attribute TimeClockData, Location financial year Synonyn for tax year flat rate Attribute or class FlatRate gross salary Attribute Payslip health insurance HealthInsuranceDeduction hourly employees Synonym for hourly paid employees hourly paid Aynonym for hourly paid employees hourly paid employees Class HourlyPaidEmployee Case Study Solutions 17

18 Candidate Class/ Objects Reason for Elimination Class name hourly rate of pay Attribute HourlyPaidEmployee hours worked Attribute TimeClockData human resources Actor list of payments Derived attributes Payslip local currency Synonymfor currency location Location month Value of time monthly paid employees MonthlyPaidEmployee name Attribute Employee normal site working hours Attribute Location overtime rate Attribute Location pay Attribute Payslip pay rates Attribute Employee pay type Attribute Employee 18 Object-Oriented Application Analysis and Design for Java Technology (UML)

19 Candidate Class/ Objects list of payments Reason for Elimination Derived attribute Class name Payslip payroll clerk Actor payroll system The application payslips Payslip pension scheme PensionSchemeDeduction percentage rate deduction Attribute or class PercentageRate Planet Earth Value of location Planet Tax PlanetTax Planet Zog Value of location planet Attribute of Location pollution tax PollutionTax site Synonym for location social security tax SocialSecurityTax Case Study Solutions 19

20 Candidate Class/ Objects system Reason for Elimination Not relevant Class name tax deductions Attribute Payslip tax year Attribute Tax tiered rates TieredRate time clock Actor time clock information TimeClockData time clock system Actor total deductions Attribute Payslip weekly calculation weekly paid employees weekly payroll Synoym for weekly payroll Use Case WeeklyPaidEmployee weekly rate of pay Attribute WeeklyPaidEmployee 20 Object-Oriented Application Analysis and Design for Java Technology (UML)

21 Risk Assessment Risk is a very subjective subject. Here is the author s simplified risk analysis ( using threerisk categories) with some brief reasoning: Case Study Solutions 21

22 Key High risk -reason customer needs to see working software, so these Use Cases will gives a working product. Medium risk -will add some more functionality, and the time interface could be tricky. Low Risk -n ot essential or not needed for some time. 22 Object-Oriented Application Analysis and Design for Java Technology (UML)

23 Packaging Use Cases By Risk If the system was larger, you could do further risk assessment to break into smaller packages. In a real project, you would do several iterations in the inception and elaboration phases before moving onto the build iterations. In this case study, time constraints make it imperative to compress several increments into one. Case Study Solutions 23

24 Activity Diagram Monthly Pay Run 24 Object-Oriented Application Analysis and Design for Java Technology (UML)

25 Note There are alternation notations for showing a loop.they require nested activities diagrams. See UML documentation for details. You could have shown a nested activity diagram for Calculate Company Deduction, Calculate Tax Deduction, and Print each Deduction. Case Study Solutions 25

26 High-Level Packaging 26 Object-Oriented Application Analysis and Design for Java Technology (UML)

27 Deployment Diagram Case Study Solutions 27

28 Key Abstractions 28 Object-Oriented Application Analysis and Design for Java Technology (UML)

29 Adding Attributes Case Study Solutions 29

30 Adding Associations 30 Object-Oriented Application Analysis and Design for Java Technology (UML)

31 Adding Multiplicity Case Study Solutions 31

32 Qualified Associations 32 Object-Oriented Application Analysis and Design for Java Technology (UML)

33 Adding Inheritance Some of these could have been just attribute values. But they differ in behavior or attributes, so you have made them extend a base class. Note You have also added a couple of role names. Case Study Solutions 33

34 Additional Classes and Attributes You have added new classes and attributes, including an association class (AmountDeducted), and including a constraint ( the TierRate must be applied in order). 34 Object-Oriented Application Analysis and Design for Java Technology (UML)

35 Adding Aggregation & Composition You have based the distinction on ownership, e.g. if the TierRate objects are only needed for one PlanetTax object. When that dies, they die too. Case Study Solutions 35

36 Sequence Diagram I Monthly Payroll Run The details of each deduction has been omitted from here. Calculate pay has also been excluded. 36 Object-Oriented Application Analysis and Design for Java Technology (UML)

37 Note This highlighted a missing class from our diagram, namely the DeductionSummary, so you have added this. Alternatively, you could have derived the values from all of the Timeslips to avoid creating this extra class. However, you would then have had to go back and edit our Use Case Form for PayrollRun etc. Case Study Solutions 37

38 Sequence Diagram II Monthly Payroll Run Showing Delegation 38 Object-Oriented Application Analysis and Design for Java Technology (UML)

39 Sequence Diagram III For Social Security Tax Calculations One of the many alternative Sequence Diagrams for the Monthly PayrollRun Use Case. This one uses some delegation. The Deduction object will add directly to the Timeslip object, and will do its own printing. Case Study Solutions 39

40 Sequence Diagram IV Revised for Monthly Payroll Run Shows missing interaction. In design, you can choose to do this with a Constructor. 40 Object-Oriented Application Analysis and Design for Java Technology (UML)

41 State Transition Diagram For Payslip Class It shows that you have missed an important interaction in our sequence diagram( namely to initialise the pay details ). It also highlights that you should ensure that you cannot change the details once saved. Case Study Solutions 41

42 Removing Association Class You have removed the association class by putting the class between the two associated classes.this has removed the many to many relationship. 42 Object-Oriented Application Analysis and Design for Java Technology (UML)

43 Revised Logical Packaging As the diagrams are getting complicated, you need to look at them in packages. Here are the two Business Model Packages, and one new Controller Package. Case Study Solutions 43

44 Deduction Logical Packaging You have included both Tax and Company Deductions in one package. This is contrary to the original planned packages. This has been done this for the purpose of brevity on the course. 44 Object-Oriented Application Analysis and Design for Java Technology (UML)

45 Employee Logical Packaging We have included the location classes here.in practice, they perhaps should be in a separate package. One option here would be to delegate the Pay to a PayType, Monthly, Weekly etc would then inherit from that class, thus making it easy for an Employee to change their PayType. However this was not in the specification, so you will not complicate the diagram here. Case Study Solutions 45

46 Miscelleanous Notes and Changes The attribute monthlycharge PensionDeductions was changed to annualcharge, so it can apply to different Employees Pay Types. The Domain expert points out that the SiteOverTimeRate will change, therefore you need to record the date of the change and store a list. Having decided to keep the Employee as the base class for different types, you will end up with this being abstract. The scoped down problem doesnt need to keep a history of salary changes, or timeslips. So once pay is processed the Timeslip objects are destroyed. The hours works are integral. Payslip objects do need to be kept. 46 Object-Oriented Application Analysis and Design for Java Technology (UML)

47 Adding Delegation The class CompanyDeduction served no purpose so you have deleted it. Given that several taxes and other deductions share common strategies of calculating deductions, you have delegated the common features, using the Strategy Pattern. You can use an Abstract Factory Pattern to set up the correct deduction strategy for the tax, or deduction. This is just one solution, there are many others, some more flexible, however you are trying to keep the scope limited. Case Study Solutions 47

48 The Deduction, Tax, and DeductionStrategy are all abstract classes. We have not shown CountryTax to keep diagram clearer, but it still exists. 48 Object-Oriented Application Analysis and Design for Java Technology (UML)

49 Monthly Pay Run Sequence Diagram in Design This is one sequence of events for the Monthly Pay Run. Case Study Solutions 49

50 Pay Run Sequence Diagram for Pay Run in Design This is just one sequence of events for the Pay Run. 50 Object-Oriented Application Analysis and Design for Java Technology (UML)

51 Calculate Deduction Sequence Diagarm In Design This is just one sequence of events for the Pay Run. This is part of the Pay Run Uses Case. Case Study Solutions 51

52 Tiered Rate Deduction Sequence Diagram in Design This is just one sequence of event. This is part of the Pay Run Uses Case. Although not part of the current iterations, above is the sequence diagram for calculating tiered deductions. The class TieredRate now performs the behaviour originally given to the PlanetTax class. 52 Object-Oriented Application Analysis and Design for Java Technology (UML)

53 State Transition Diagram For Payslip Class Case Study Solutions 53

54 Activity Diagram For Monthly Pay Run 54 Object-Oriented Application Analysis and Design for Java Technology (UML)

55 Pay Run Package I Simple Class Diagram Case Study Solutions 55

56 Pay Run Package II Pay Run Package Class Diagram 56 Object-Oriented Application Analysis and Design for Java Technology (UML)

57 Employee Package I Simple Employee Package Class Diagram Case Study Solutions 57

58 Employee Package II Employee Package Class Diagram 58 Object-Oriented Application Analysis and Design for Java Technology (UML)

59 Deduction Package Deduction Package Class Diagram Case Study Solutions 59

60 60 Object-Oriented Application Analysis and Design for Java Technology (UML)