April 27, 2004CS 562 - WPI1 CS 562 Advanced SW Engineering Lecture #3 Tuesday, April 27, 2004
April 27, 2004CS 562 - WPI2 Class Format for Today Turn in Paper #1 Questions Lecture #3: Chapter 2 – Model Definition Exercise?
April 27, 2004CS 562 - WPI3 Questions? From last week’s class From the reading About the papers/project? Anything else? Everyone has books, all set with reading?
April 27, 2004CS 562 - WPI4 COCOMO II Model Definition Boehm, et al Chapter 2
April 27, 2004CS 562 - WPI5 Overview Model Types Post-Architecture Model Early Design Model How are these models defined? Review Estimation Equations on page 13: Amount of effort in Person-Months (Eq. 2.1) Amount of calendar time (Eq. 2.2) Review average-sized project example, p. 14
April 27, 2004CS 562 - WPI6 Sizing Types of size data used by COCOMO II: New code Reused code Automatically translated code How are the types of data treated differently?
April 27, 2004CS 562 - WPI7 Counting Source Lines of Code Best source for estimating new lines of code is historical data. What other options are given when lacking historical data? Support software, such as test drivers: Include/exclude? When to estimate, why? Use of SEI definition checklist (p. 16)
April 27, 2004CS 562 - WPI8 Unadjusted Function Points How do function points measure a project? Review user function types – Table 2.1, p. 17 What other factors are considered? 4-step procedure for determining UFPs Steps listed on page 18 Complexity levels & weights – Tables 2.2, 2.3 Relating UFPs to SLOC Conversion ratios in Table 2.4, p. 20 What are USR slots used for?
April 27, 2004CS 562 - WPI9 Nonlinear Reuse Effects Review Figure 2.2 & Equation 2.3, p. 21, and Figure 2.3, p. 22: What are these about? How & why are the effects nonlinear? Discuss reuse penalties: Software understanding Module-interface checking
April 27, 2004CS 562 - WPI10 Reuse Model Estimate amount of software to be adapted using 3 degree-of-modification factors: Percentage of design modified Percentage of code modified Percentage of integration effort required Review Equation 2.4, page 22 How does this relate to Tables 2.5, 2.6, 2.7? Also see ranges of reuse factors, Table 2.8, p. 26
April 27, 2004CS 562 - WPI11 Req’s Evolution & Volatility Adjust effective size of product caused by requirements evolution & volatility What factors contribute to such volatility? REVL = % of code discarded due to requirements evolution Review example, bottom of p. 25 How is this factor used to calculate size? See Equation 2.5, p. 26
April 27, 2004CS 562 - WPI12 Automatically Translated Code Estimating costs of reengineering and conversion, using tools for restructuring How do the tools impact the estimate factors? Equation 2.6, p. 27, shows how auto translation affects estimated effort What is AT? What is ATPROD? How are these factors calculated/estimated?
April 27, 2004CS 562 - WPI13 Sizing Software Maintenance Scope of SW maintenance Includes adding new capabilities & fixing or adapting existing capabilities Excludes major product rebuilds and development of sizable interfacing systems Review Equations 2.7 – 2.10, page 28
April 27, 2004CS 562 - WPI14 Effort Estimation Expressed in terms of person-months How is PM defined? How does this relate to TDEV? Review Eq. 2.11, p. 29, and discuss inputs to this equation: A, Size, E, Em i How do cost drivers fit in – individual project components, vs. project as a whole?
April 27, 2004CS 562 - WPI15 Scale Factors Economy vs. diseconomy of scale What produces one or the other effect? How does this impact effort estimation? Review Eq. 2.12, p. 31, and Table 2.10, p. 32 What are these about? Discuss example on bottom of p. 31 Review various scale factors in Sections 18.104.22.168 through 22.214.171.124
April 27, 2004CS 562 - WPI16 Effort Multipliers Used in Eq. 2.11, what are they? Post-Architecture vs. Early Design EM’s Post-Architecture: RELY, DATA, CPLX, RUSE, DOCU, TIME, STOR, PVOL, ACAP, PCAP, PCON, APEX, PLEX, LTEX, TOOL, SITE, SCED Pages 41 – 51 Early Design: RCPX, PDIF, PERS, PREX, FCIL Pages 51 – 55
April 27, 2004CS 562 - WPI17 Multiple Modules & Schedules 6 steps for estimating multiple module effort Why not just sum up individual module efforts? Review steps listed on pages 55 – 57 Schedule estimation – Eq. 2.14, p. 57 Review factors that go into this equation More info in Appendix A.
April 27, 2004CS 562 - WPI18 SW Maintenance & Decisions How is SW Maintenance defined? What assumptions are made? Review Eq. 2.15 & 2.16, p. 59 Section 2.6 presents an example for an auto- parts company named UST. Discuss Sections 2.6.1 – 2.6.9, pgs. 60 – 68. More examples (in 2 weeks) in Chapter 3.
April 27, 2004CS 562 - WPI19 For Next Time Read Chapters 1-9 of Brooks Come prepared to discuss Proposal 1 for term project due