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Software Maintenance Himanshu Reg.No - 20114024 Roll no - 25

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Software Engineering Maintenance

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Page 1: Himanshu

Software Maintenance

HimanshuReg.No - 20114024Roll no - 25

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Software Maintenance, definition

The process of modifying a software system or component after delivery tocorrect faults,improve performance or otherattributes, or adapt to a changed environment

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Software Maintenance

Main issues: why maintenance is such an issue reverse engineering and its limitations how to organize maintenance

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Relative distribution of software/hardware costs

HardwareDevelopment

Software

Maintenance

1955 1970 1985Year

100

60

20

Perc

ent o

f tot

al c

ost

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• Why does software maintenance cost so much?

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Maintenance is thus concerned with:

• correcting errors found after the software has been delivered

• adapting the software to changing requirements, changing environments, ...

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Key to maintenance is in development

• Higher quality less (correctie) maintenance

• Anticipating changes less (adaptive) maintenance

• Better tuning to user needs less (perfective) maintenance

• Less code less(preventive) maintenance

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Kinds of maintenance activities

• corrective maintenance: correcting errors

• adaptive maintenance: adapting to changes in the environment (both hardware and software)

• perfective maintenance: adapting to changing user requirements

• preventive maintenance: less code , increasing the system’s maintainability

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Distribution of maintenance activities

corrective 21%

adaptive 25%

preventive 4%

perfective 50%

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Poblems during maintenance

• Persons may not have adequate knowledge about programs ,they may introduce changes to programs without being aware of their effects on other parts of system –”ripple effect”

• Users lack the ability to express problem regarding software to programmers in their understandable form

• Systems not designed for change and hardly any scope for change,maintenance will be very difficult

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Maintenance Process

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Maintenance models

• Quick fix model• Iterative Enhancement Model• Reuse Oriented Model

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Quick Fix Model

• Find problem fix it as quickly as possibe• Fixing without detailed analysis of long term effect of editing

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Iterative Enhancement Model• Changes to software are throughout its lifetime are iteative

• It requires full documentaion• It is based on ability fo maintenance team to

analyze the existing product full

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Reuse Oriented Model• Maintenance involves reuse of existing program components• It requires full doc.• It is based on ability of maintenance team to analyze the existing product fully

• It has four parts– Identification of parts of old system– Understanding these system parts– Modification fo old parts to new ones– Integration of modified parts into new system