An Introduction to Object-Oriented Systems Analysis and Design with UML and the Unified Process McGraw-Hill, 2004 Stephen R. Schach [email protected] 5 — Unit AChapter OverviewMSG Foundation Case StudyInitial Understanding of the Domain: MSGInitial Understanding of the Domain: MSG (contd)Mortgage Payments: First MonthMortgage Payments: Second MonthMortgage Payments: After 15 years, after 30 yearsInsurance PremiumsInsurance Premiums (contd)Real Estate TaxesBorrowing LimitsOther CostsOther Costs (contd)Initial Business Model: MSG Case StudyInitial Business Model: MSG Case Study (contd)Business Model: MSG FoundationUse Case Estimate Funds Available for WeekUse Case Apply for an MSG MortgageUse Case Compute Weekly Repayment AmountWho Is an Actor?Who Is an Actor? (contd)Slide 24Use Case Manage an InvestmentUse Case Manage an Investment (contd)Use-Case Diagram of the Initial Business ModelInitial Requirements: MSG Foundation Case StudySlide 29Slide 30Initial Use-Case Diagram: MSG Case StudyContinuing the Requirements Workflow: MSGConditions for an MSG Mortgage (contd)Algorithm to Determine If Funds Are AvailableSlide 35Requirements of the Pilot ProjectInvestment DataOperating Expenses DataMortgage DataMortgage Data (contd)Reports Required for the Pilot ProjectRevising the Requirements: MSG Case StudyRevising the Requirements: MSG (contd)Estimate Investment Income for WeekEstimate Investment Income for Week (contd)First Iteration of the Revised Use-Case DiagramSlide 47Update Estimated Annual Operating ExpensesEstimate Operating Expenses for WeekSecond Iteration of Revised Use-Case DiagramSlide 51Slide 5A.1Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. An Introduction toObject-Oriented Systems Analysis and Design with UML and the Unified Process McGraw-Hill, 2004Stephen R. [email protected] 5A.2Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. CHAPTER 5 — Unit ATHE REQUIREMENTS WORKFLOW IISlide 5A.3Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Chapter OverviewMSG Foundation Case StudyInitial Understanding of the Domain: MSG Foundation Case StudyInitial Business Model: MSG Case StudyInitial Requirements: MSG Foundation Case StudyContinuing the Requirements Workflow: MSG Foundation Case StudyRevising the Requirements: MSG Foundation Case StudyRefining the Revised Requirements: MSG Foundation Case StudySlide 5A.4Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. MSG Foundation Case StudyThe Martha Stockton Greengage Foundation (“MSG”) provides low cost mortgage loans to young couples The trustees commission a pilot project–An information system to determine how much money is available each week to purchase homesSlide 5A.5Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Initial Understanding of the Domain: MSGA mortgage is a loan in which real estate is used as securityExample: House costs $100,000Buyer pays a 10% deposit and borrows the balance–The principal (or capital) borrowed is $90,000Loan is to be repaid monthly over 30 years–Interest rate of 7.5% per annum (or 0.625% per month)Slide 5A.6Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Initial Understanding of the Domain: MSG (contd)Each month, the borrower pays $629.30–Part of this is the interest on the outstanding balance–The rest is used to reduce the principalThe monthly payment is therefore often referred to as P & I (principal and interest)Slide 5A.7Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Mortgage Payments: First MonthIn the first month the outstanding balance is $90,000–Monthly interest at 0.625% on $90,000 is $562.50 –The remainder of the P & I payment of $629.30, namely $66.80, is used to reduce the principal At the end of the first month, after the first payment has been made, only $89,933.20 is owed to the finance companySlide 5A.8Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Mortgage Payments: Second MonthIn the second month the outstanding balance is $89,933.20 –Monthly interest at 0.625% on $89,933.20 is $562.08 –The remainder of the P & I payment of $629.30, namely $67.22, is used to reduce the principal At the end of the second month, after the second payment has been made, only $89,865.98 is owed to the finance companySlide 5A.9Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Mortgage Payments: After 15 years, after 30 yearsAfter 15 years (180 months) the outstanding balance is $67,881.61–Monthly interest at 0.625% on $67,881.61 is $424.26 –The remainder of the P & I payment of $629.30, namely $205.04, is used to reduce the principal After 30 years (360 months), the entire loan will have been repaidSlide 5A.10Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Insurance PremiumsThe finance company requires the borrower to insure the house–If the house burns down, the check from the insurance company will then be used to repay the loanSlide 5A.11Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Insurance Premiums (contd)The insurance premium is paid once a year by the finance company–The finance company requires the borrower to pay monthly insurance installments–These are deposited in an escrow account (a savings account)The annual premium is then paid from the escrow accountSlide 5A.12Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Real Estate TaxesReal-estate taxes paid on a home are treated the same way as insurance premiums–Monthly installments are deposited in the escrow account–The annual real-estate tax payment is made from that accountSlide 5A.13Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Borrowing LimitsA mortgage will not be granted unless the total monthly payment (P & I plus insurance plus real-estate taxes) is less than 28% of the borrower’s total incomeSlide 5A.14Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved. Other CostsThe finance company requires a lump sum up front in return for lending the money to the borrower–Typically, the finance company will want 2% of the principal (“2 points”)–For the $90,000 loan, this amounts to $1,800Slide 5A.15Copyright © 2004 by The