Not your Father s Function Points Shortcuts to Functional

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Not your Father’s Function Points Shortcuts to Functional Size Presented by Carol A. Dekkers, CMC, CFPS Quality Plus Technologies, Inc. Email: Dekkers@qualityplustech. com www. Quality. Plus. Tech. com © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 1

ISO Standards for FSM ‘Functional Size Measurement (FSM)’ defined by ISO/IEC 14143 -1: 1998: • Functional Size Measurement (FSM): The process of measuring Functional Size. • Functional Size: A size of the software derived by quantifying the Functional User Requirements. • Functional User Requirements: A sub-set of the user requirements. The Functional User Requirements represent the user practices and procedures that the software must perform to fulfil the users’ needs. They exclude Quality Requirements and any Technical Requirements. © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 4

ISO Standards for FSM § ISO/IEC 14143: parts 1 -6 (framework suite) § ISO conformant FSM Methods § § ISO/IEC 19761: 2002 COSMIC-FFP ISO/IEC 20926: 2002 IFPUG 4. 1 Unadjusted ISO/IEC 20968: 2002 Mk II Function Point Analysis ISO/IEC 24570: 2004 NESMA functional size measurement method version 2. 1 All rely on functional user requirements © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 5

ISO/IEC Standards 15939: Software measurement framework § Goal driven measurement (based on GQM) § Practical Software & Systems Measurement (PSM) © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 7

IFPUG* CPM 4. 2 § 5 functional components § Persistent data: ILF, EIF § Elementary processes: EI, EO, EQ § Each component has Low, Average, High, values that translate to point scores *IFPUG = International Function Point Users Group www. ifpug. ORG © 2005 Quality Plus Technologies, Inc. EI ILF EO ILF EQ EIF www. qualityplustech. com Page 9

IFPUG CPM 4. 2 § Enhancements without base count rely on judgement (reverse engineering) § “Count” depends on knowledge of functions before enhancement + requirements © 2005 Quality Plus Technologies, Inc. New Enhanced XX X Removed www. qualityplustech. com Page 10

IFPUG CPM 4. 2 § VAF non-functional complexity § § 14 situational General Systems Characteristics Varied use in industry Outside ISO definition of FSM Duplication of COCOMO II factors? © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 11

Shortcuts Shortcut Basis 1 Early&Quick IFPUG type components 2 IFPUG 4. 2 all average # of each IFPUG function type in requirements scored as avg 4 ISBSG profile Single component prorated by % 5 KISS Quick 28 types of IFPUG-like functions 6 One file model Maintained entities * 31 7 Patterns Verb words * verb average FP © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 14

Sample requirements New development The software must provide: § Processes to add, update, and terminate employees; also merge duplicate employee records § A weekly report listing employees whose information has changed in the past 7 days § View/browse of stored employee data § User security validation (against an external security database) § Complex algorithms to encrypt the employee date of birth and social security number to prevent disclosure © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 15

IFPUG 4. 2 (not shortcut) Add, change, terminate employees Employee entity Merge duplicate employee records Weekly report with calculations View/browse employee data (calc) User validation Security reference data Algorithms Total <16 DET, 1 FTR= 3 L EI <50 DET, 1 RET= L ILF <16 DET, 1 FTR= L EI <20 DET, 1 FTR=1 L EO <19 DET, 1 FTR=1 L EQ <50 DET, 1 RET=1 L EIF N/A = 9 FP = 7 FP = 3 FP = 4 FP = 3 FP = 5 FP = 0 FP = 35 FP © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 16

Shortcut 1 Early & Quick (E&QFP 2. 0) Total = 44 FP Conte, Iorio, Meli, Santillo – Data Processing Organisation 2004 http: //www. dpo. it/english/resources/papers. htm#se © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 17

Shortcut 2 IFPUG 4. 2 all average Add, change, terminate employees 3 A EI 12 FP Employee entity 1 A ILF 10 FP Merge duplicate employee records 1 A EI 4 FP Weekly report with calculations 1 A EO 5 FP View/browse employee data (calc) 1 A EO 5 FP User validation 1 A EQ 4 FP Security reference data 1 A EIF 7 FP Algorithms N/A 0 FP Total © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 18

Shortcut 3 B a Point Mix, New Development ISBSG Profile Functionsed o Ea n EI < requi r Add 16 DE emen T, 1 ts Chg emplo yee FTR for E Ter emplo I (k me now yee lik Me mp ely n): rge loye lik LE Tot d atin al E ups e lik ely L E I g, B I FPA enc l ely L I 3 F FP ME hmar ikel EI P THO king Usi y. L 3 F &R D: I ng EI FPU ese P pro 3 F G 4 arch file ] P Sui te R 3 F 1 elea 2/ 12 P se 9 28. FP 9 ch %4 2 F P © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 19

Shortcut 5 One file model (rule of 31) For each persistent entity: Multiply * 31 FP: Add A EI 4 FP Update A EI 4 FP Delete A EI 4 FP Inquiry A EQ 4 FP Output A EO 5 FP Entity A ILF 10 FP Total 31 FP One ILF (employee) = 31 FP + 1 EIF (security) Total = 36 FP © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 21

Shortcut 6 Patterns (verbs) Verb Pattern Shall enable a user to enter… Create & update (2 A EI), del (L EI), query (L 21 FP EQ), datastore (L ILF) Able to combine … Presentation of results to user (includes calculations) H EO N/A –n op FP Notify reced Email to users (with sound) A EQ ent s fo Display data (A EQ), Approve (L EI) Approve r cu rren t ap Produce output on Compilepreports on 3 unique media for lica fiche, screen, file different users n tio (3 A EO) In batch A EI, L ILF Input & Store Etc. specific to app. 7 FP 4 FP 7 FP 15 FP 10 FP Number of patterns depends on base © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 22

Shortcuts Results for sample requirements Shortcut FP Comments IFPUG 4. 2 regular 35 Need DET, RET, FTR & all functions 1 Early&Quick 44 Easy if all functions unknown 2 IFPUG 4. 2 all average 47 Good if all functions known 3 ISBSG profile 42 Good if requirements incomplete 4 KISS Quick 42 Easy checklist if all functions known 5 One file model 36 Quickest if entities known. Need + EIF 6 Patterns N/A Depends on homogenuity of historical requirements and wording. Can be done ahead during application count © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 23

Estimates vs. Guesstimates Givens: q Size is major determinant q Functional size known functional requirements q ‘Count’ needs solid requirements q (Guess)timate only as strong as weakest link q Premature pursuit of accuracy © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 26

Estimates vs. Guesstimates Sizing shortcuts: q Appropriate for early phases (IDEF 0) q Educated guess when details few q Minimize sizing effort q Level of accuracy (‘measure with calipers, cut with axe’) q No platinum bar q Gains buy-in © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 27

Summary § Functional size measurement can be simplified § Not your father’s function points § Useful as second opinions § Easy useful © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 29

Further references § International Function Point Users Group (IFPUG) www. IFPUG. ORG § International Software Benchmarking Standards Group (ISBSG): www. ISBSG. org § ISO/IEC 15939 (2002) Measurement Framework § Practical software & systems measurement: www. psmsc. com § Quality Plus Technologies website: www. qualityplustech. com § The Goal/Question/Metric Method by Van Solingen & Berghout © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 30

Not your Father’s Function Points Shortcuts to Functional Size Carol Dekkers, CMC, CFPS, P. Eng. Quality Plus Technologies, Inc. Email dekkers@qualityplustech. com Phone +1 727 393 -6048 Mobile +1 727 686 -1329 © 2005 Quality Plus Technologies, Inc. www. qualityplustech. com Page 31