Some Size factors in software engineering

Total effort devoted to software
Distribution of effort
Project size categories
How programmers spend their time

1. Some size factors in software engineering Mrs. G. Chandraprabha Assistant Professor of IT V.V.Vanniaperumal College for Women Virudhunagar

2. contents Total effort devoted to software Distribution of effort Project size categories How programmers spend their time

3. Some size factors The level of effort devoted to software development and maintenance The distribution effort among activities Size categories for different software projects Information regarding the above are concluded based on the resuits summarized from different software projects from different organizations

4. Total effort devoted to software It is estimated that the total amount spent on all aspects of computing in the united states in 1980 is 5% of gross nation product It is further estimated that it is increased to 8% in 1985 and 12.5% by 1990 In contrast US automobile industry contributed 2.3% to the GNP in 1990 When comparing this it may be concluded that it indicates the growing importance of computing technology But current demand for software technologists exceeds the available supply It is estimated that demand will exceed supply by 7,50,000 to 20,00,000 people by 1990 So, the major goal of software engineering is to provide tools and techniques to increase the productivity of the available software engineers

5. Distribution of effort Life span for a software product 1 to 3 years-Development 5 to 15 years-Maintenance The distribution effort between development and maintenance has reported as 40/60,30/70 and 10/90 This is not surprising because maintenance comprises all the activities following initial release of a software product Software maintenance involves three types of activities Enhancing the capabilities of the product Adapting the product to new environment Correcting bugs Distribution of effort for enhancement , adaptation and correction is 60%,20% and 20% During development distribution of effort is Analysis and design(40%) Implementation , debugging & unit testing(20%) Integration and acceptance testing(40%)

6. PROJECT SIZE CATEGORIES Project size is a major factors that determines the level of management controls The following categories give some indication of software project size Trivial projects Small projects Medium size projects Large projects Very large projects Extremely large projects

7. Project size categories Trivial project: No . of programmers:1 Duration : few days , few weeks Product size:500 lines of source code Packed in:10-20 subroutines These programs are often personal software These are developed exclusively for the use of the programmer Small amount of formal analysis , elaborate design documents , extensive test panning or supporting documents are needed

8. Project size categories Small projects: No. of programmers:1 Duration:1-6 months Product size:1000-2000 lines of source code Packed in 25-50 Subroutines These programs have no interactions with other programs It requires little interactions between programmers and customers Standardized techniques and notations , standardized documents and systematic project reviews should be used in small project

9. Project size categories Medium sized projects: No . of programmers:2-5 Duration:1-2 years Product size : 10000-15000 lines of source code Packed in: 250-1000 routines To develop such programs,interactions among programmers and customers is required A certain degree of formality is required in planning , documents and project reviews Most application programs , system programs are developed in 2 years or less by 5 years

10. Project size categories Large size project: No .of programmers:5-20 Duration:2-3 years Product size:50000- I lakh lines of source code Packed in : several subsystem It has significant interactions with other programs and subsystem Communication among programmers , manager , customers is needed It required more than 1 programming team It involves more than 1 level of management Systematic process , standardized documents and formal reviews are essential

11. Project size categories very Large project: No . of programmers:100-1000 Duration:4-5 years Product size : 1 million source lines It consists of several major subsystem , each of which forms a large system The subsystem has complex , interactions with one another and with other separate system which we developed It involves telecommunication and multi-tasking It includes large OS , large database system and military commander and control system

12. Project size categories extremely Large project: No .of programmers:2000-5000 Duration:10 years Product size:1 million -10 million lines of source code It consists of several very large subsystem It involves real-time processing , telecommunications , multi tasking and distributed processing It involves air traffic control , ,military commander control system

13. How programmers spend their time In 1964 , bell labs conducted a time and motion study of 70 programmers to determine how they spend their Writing programs :13% Reading programs and manuals:16% Job communication:32% Personal :13% Miscellaneous:15% Training :6% Mail:5%

14. How programmers spend their time When we look the results , the fact is a programmer spend only 13% of time in writing programmers It may appear to be unreasonable For example consider the personal time of 13% Assume 260 days potential work days per year (5*52=260) Assume , paid holidays=11 days Paid vacation days=15 days Sick leave=5 days Jury duty=3 days , extra vacation etc.., It results in total of 34 days of personal time which is approximately 13% of 260 days Similarly , 1 hour per day for coffee break , personal phone calls , visits to restrooms plus 13 days of travel time The experiment is done only in 1964 , but still is the situation Many reasons for underestimating software project cost are failure to take 39% overhead time of the programmers(13+15+5+6) and 48% time spend in job communication and reading of programs and manuals(32+16=48)

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