Producing Production Quality Software Lecture 14: Group Programming Practices Data Prof. Arthur P. Goldberg Fall, 2005

Transcription

1 Producing Production Quality Software Lecture 14: Group Programming Practices Data Prof. Arthur P. Goldberg Fall, 2005 Best Technical Practices for MIS Software From Software Assessments, Benchmarks, and Best Practices, by Capers Jones, 2000 Best Project Management Practices for MIS Software Function Point Analysis Productivity Measures Annual Assessments and Benchmarks Project Management Training Project Management Tools Personnel Management Tools Activity-Based Cost Estimates Empirical Productivity Data ERP Data Client/Server Planning Data Milestone Tracking Best Requirements-Gathering and Analysis Practices for MIS Software Joint Application Design (JAD) Prototypes of Key Features Requirements Inspections Requirements Notations Function Point Size Requirements Change Control Best Design and Specification Practices for MIS Software Specification Segmentation Prototypes Design Inspections Best Coding Practices for MIS Software Structured Programming Comment Density and Style Mnemonic Labels Code Inspections COBOL Complexity Reduction Error-Prone Module Elimination Module-Level Defect Tracking Programming Languages Best Reusability Practices for MIS Software Reusable Database Designs Reusable Source Code libraries Best Change Control Practices for MIS Software Change Control Boards Automated Change Control Function Point Metrics for Changes p 1

2 Best User Documentation Practices for MIS Software Technical Writers Document Models Document Testing Reader Suggestions Hypertext Links Working Examples Best Quality Control and Pretest Defect Removal Practices for MIS Software Joint Application Design (JAD) Requirements Inspections Error-prone Module Elimination Quality Measurements Quality Estimation Tools Risk Analysis Best Testing Practices and Tools for MIS Software Automated test tools Test Coverage Analysis Best Maintenance and Enhancement Practices for MIS Software Portfolio Analysis Geriatric Care for Legacy Applications p 2

3 Tables from Capers Jones Table: Distribution of SPR Project Benchmarks circa 1999 Function Points End User MIS Outsource Commercial Systems Military Total , , ,030 1, , , ,325 10, , Total 130 3,300 1, , ,155 Percent Table: Five Levels of the SEI CMM SEI Maturity Levels Meaning Frequency or Occurrence, % 1 = Initial Chaotic = Repeatable Marginal = Defined Adequate = Managed Good to Excellent = Optimizing State of the Art 0.5 Table: Five Levels of the SPR Excellence Scale SPR Excellence Scale Meaning Frequency or Occurrence, % 1 = Excellent State of the Art = Above Average Superior to most companies = Average Normal in most factors = Below Average Deficient in some factors = Poor Deficient in most factors 3.0 Table: Approximate Conversion Between SPR and SEI Software Scores SPR Scoring Range Equivalent SEI Score Approximate Frequency, % , poor 1 Initial , below average 2 Repeatable , average 3 Defined , above average 4 Managed , excellent 5 Optimizing 2.0 p 3

4 Table: United States Software Productivity Rates circa 1999, function points per staff month Size, function points End User Software MIS Outsource Commercial Systems Software Military , , , Average Table: Size Ranges of Software in Both Function Points and LOC Application Size, function points Size, LOC LOC per function Point Personal programs 25 1, Web Applets 50 3, Computer Games 3, , Word Processors 3, , Spreadsheets 3, , Client/server applications 7, , Database packages 7, , Telephone switching systems 7, , Manufacturing applications 7, , Large business applications 10,000 1,050, Major corporate applications 25,000 2,625, Major government applications 50,000 5,250, Operating systems 75,000 11,250, Enterprise systems 150,000 18,750, Major defense systems 250,000 25,000, p 4

5 Table: Ratios of Logical Source Code Statements to Function Points for Selected Programming Languages Using Version 4.1 of the IFPUG rules Source Statements per Function Point Language Nominal Level Low Mean High Basic Assembly Macro Assembly C Fortran COBOL Pascal PL/I Ada C Ada Visual Basic Smalltalk SQL Table: Productivity Paradox with LOC Metrics Assembly Source Code (1,000,000 LOC), C++ Source Code (500,000 LOC), Difference (500,000 LOC Activity Staff Months Staff Months total) Difference Testing/Debugging Paper Documents Coding Management Total 2,000 1, Application Cost $20,000,000 $11,500,000 $8,500,000 LOC per staff month Cost per LOC $20.00 $ $3.00 Table: U.S. Averages for Defect Removal Efficiency Defect Origins Defects Per Function Point Removal Efficiency, % Delivered Defects Requirements Design Coding Document Bad Fixes Total p 5

6 Table: Defect Potentials and Removal for the SEI CMM Levels SEI CMM Level Defect Potentials Removal Efficiency, % Delivered Defects Table: Impact on Productivity of Positive and Negative Adjustment Factors (sorted in order of maximum positive impact) Change in Productivity Negative New Development Positive New Development (%) Factors Factors Increase Decrease Re-use of high-quality deliverables Re-use of poor-quality deliverables High management experience Management inexperience High staff experience Staff inexperience Effective methods/process Ineffective methods/process Effective management tools Inadequate management tools Effective technical CASE tools Inadequate technical CASE tools High-level programming languages Low-level programming languages Quality estimating tools No quality estimation Specialist occupations Generalist occupations Effective client participation No client participation Formal cost/schedule estimates Informal cost/schedule estimates Unpaid overtime 15 0 No unpaid overtime Use of formal inspections No use of inspections Good office ergonomics Crowded office space Quality measurement No quality measurements Low project complexity High project complexity Quick response time Slow response time Moderate schedule pressure Excessive schedule pressure Productivity measurements 10 7 No productivity measurements Low requirements creep 9 77 High requirements creep Annual training of >10 days 8 12 No annual training No geographic separation 8 24 Geographic separation High team morale 7 6 Poor team morale Hierarchical organization 5 8 Matrix organization Total 800 1,067 CASE = Computer-Aided Software Engineering p 6

7 Function Points From David Garmus, David Herron, Function Point Analysis: Measurement Practices for Successful Software E.g.: External Interface Files - An external interface file (EIF) is a user-identifiable group of logically related data or control information referenced by the application but maintained within the boundary of a different application. The primary intent of an EIF is to hold data referenced through one or more elementary processes within the boundary of the application counted. An EIF counted for an application must be in an ILF in another application. Table: IFPUG's Unadjusted Function Point Table Function Levels Components Low Average High External Input (EI) x 3 x 4 x 6 External Output (EO) x 4 x 5 x 7 External Inquiries (EQ) x 3 x 4 x 6 Internal Logical Files (ILF) x 7 x 10 x 15 External Interface Files (EIF) x 5 x 7 x 10 Table: Sample IFPUG's Unadjusted Function Point Table Function Levels Components Low Average High Total External Input (EI) 3 x 3 6 x 4 x 6 33 External Output (EO) x 4 x 5 1 x 7 7 External Inquiries (EQ) x 3 3 x 4 x 6 12 Internal Logical Files (ILF) 3 x 7 x 10 x External Interface Files (EIF) 1 x 5 x 7 x 10 5 Total unadjusted function points (UFP) = 78 p 7

8 Literature Managing the Software Process, Watts S. Humphrey, Addison-Wesley Publishing, 1989 Extremely influential; SEI; capability maturity model (CMM), focused on mandated activities. Quality Software Management, By Gerald M. Weinberg, Dorset House Publishing In 4 volumes. Focused on philosophy, attitudes, (and behaviors derived from the attitudes). The leading work on software development psychology. Volume 1: Systems Thinking, 1992 Volume 2: First-Order Measurement, 1993 Simple measurements are typically accurate enough to monitor software project Volume 3: Congruent Action, 1994 Congruent, as in congruent triangles; actions should convey the same attitude and desire; otherwise, the recipient is confused. Volume 4: Anticipating Change, 1997 Software Project: Survival Guide (How to Be Sure Your First Important Project Isn't Your Last), Steve McConnell, Microsoft Press, 1998 Rapid Development (Taming Wild Software Schedules), Steve McConnell, Microsoft Press, 1996 Two of 3 books by McConnell. For small (typically MIS) projects, advocates frequent working releases; somewhat like extreme Programming (XP). The Psychology of Computer Programming, Gerald M. Weinberg, Dorset House Publishing, Reprint of a 1973 classic. Software Cost Estimation with Cocomo II, Boehm., Abts., Brown, Chulani, Clark, Horowitz, Madachy, Reifer, Steece, Prentice Hall, 2000 How much will it cost to build a system? Function Point Analysis (Measurement Practices for Successful Software ), David Garmus, David Herron, Addison-Wesley Publishing, Probably the most effective technique for estimate project complexity. Requires training. Principals of Software Engineering Management, Tom Gilb, Addison-Wesley Publishing, 1988 Software Assessments, Benchmarks, and Best Practices, Capers Jones, Addison-Wesley Publishing, 2000 Software Tools, Kernighan and Plauger, Numerous extensive examples of software design and development. Jon Louis Bentley: Programming Pearls (2nd Edition) Writing Efficient Programs (Prentice-Hall Software Series), Out of Print More Programming Pearls: Confessions of a Coder p 8