Sixteen Questions About Software Reuse

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Sixteen Questions About Software Reuse

• William B. Frakes and Christopher J. Fox
• Communications of the ACM

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Software reuse

• The use of existing software knowledge and
  artefacts to build new software artefacts
• sometimes confused with porting
• reuse is using an asset in different systems
• porting is moving a system across environments
  and platforms

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The survey

• Surveyed
• software engineers, managers, educators, and
  other in the software development and research
  community
• About
• attitudes, beliefs, and practices in reusing code
  and other lifecycle objects
• Response from
• 113 people from 29 organizations (28 US and one
  European)
• fairly representative of experienced software
  engineers or managers at high technology companies

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16 questions

• The survey is used to answer 16 questions
  commonly asked by organizations attempting to
  implement systematic reuse.
• The answers to these questions are often taken
  for granted in the software community but without
  empirical verification
• This article uses empirical data from a survey to
  answer these questions

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Q1 How widely reused are common assets?

• Are reusable assets actually used, and are they
  found valuable?
• Answer yes and no.
• Some assets are widely used (e.g.. UNIX tools)
  and perceived to be valuable, others are not used
  by many and are not perceived to be valuable
  (e.g.. Cosmic collection form NASA)
• Possible reasons
• lack of information and education
• asset quality and ease of access
• anecdotal evidence suggest that relevant
  functionality is an important factor

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Q2 Does programming language affect reuse?

• Does certain programming languages provide better
  reuse support (e.g.. by supporting abstractions,
  inheritance, strong typing)
• The data of the survey shows the correlation of
  11 languages and the level of organizational code
  reuse.
• Findings
• languages usually thought to promote reuse show
  small correlation (e.g.. ADA and C)
• Higher level languages are no more strongly
  correlated with code reuse than is assembly
  language
• Conclusion
• Choice of programming language does not affect
  code reuse levels
• To increase reuse the focus should be on other
  factors

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Q3 Do CASE tools promote reuse?

• Many organizations regard CASE tools as a way to
  improve reuse
• The majority (75) does not agree that CASE tools
  have promoted reuse
• No significant correlation between the
  respondents degree of belief in that CASE tools
  promote reuse and the percentage of actual reuse.
• Conclusion
• CASE tools are not currently effective in
  promoting reuse
• Reasons
• CASE tools may not be used
• CASE tools may not be used correctly
• CASE tools may not promote reuse

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Q4 Do developers prefer to build from scratch or
to reuse?

• Many people believe that software engineers
  prefer to build their own software rather than
  reuse someone else's
• Statement used in the survey
• Its more fun to write my own software than to
  reuse
• Most respondent do not agree on it (72)
• Conclusion
• Most developers prefer to reuse rather than to
  build from scratch
• Contradicts conventional assumptions, but is in
  agreement with other findings of another recent
  study

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Q5 Does perceived economic feasibility influence
reuse?

• Reuse may not be done if it is not believed to be
  economically feasible.
• Levels of code reuse is compared with respondents
  agreement with the statement Reuse is
  economically feasible in my organization.
• Clear trend towards higher reuse as belief in
  economic feasibility increases
• Conclusion
• perceived economic feasibility influences reuse
• important to convince software engineers about
  the economic feasibility of reuse

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Q6 Does reuse education influence reuse?

• Comparing education about software reuse (at
  school) with individual levels of reuse shows
  that education on reuse does affect code and
  design reuse
• Comparing education about software reuse (at
  work) with organizational reuse levels of
  lifecycle objects shows that education at work
  does affect reuse
• Conclusion
• Education in school and at work improves reuse
  and is a necessary part of a reuse program

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Q7 Does software engineering experience
influence reuse?

• General assumption that experienced software
  engineers are better practitioners
• The survey shows no significant correlations
  between engineering experience and personal level
  of reuse.
• Conclusion
• Software engineering experience has no effect on
  reuse of lifecycle objects
• Maybe caused by historical lack of training in
  reuse

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Q8 Do recognition rewards increase reuse?

• Reuse incentives are considered to be necessary
  catalysts for reuse.
• recognition rewards and cash rewards
• Respondents say that rewards are rare
• no cash bonuses
• only a few with other recognition
• Comparing levels of organizational code reuse
  between the two groups rec. rewards and no
  rewards show no significant differences
• Similar findings for individual reuse
• The findings contradict the common belief that
  recognition is a sufficient reward for reuse.
• It may be that only monetary rewards are
  sufficient rewards

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Q9 Does a common software process promote reuse?

• Statement used in the survey
• A common development process has promoted reuse
  across projects in our organization.
• Respondents generally do not agree on it.
• This might mean
• no defined common process
• the process has failed to support reuse
• The correlations between the degree of agreement
  with the statement and the organizational reuse
  shows
• moderate correlation for designs, test plans, and
  test cases
• weak correlations for requirements, code, and
  user documentation
• Conclusion
• A defined software process that promotes reuse
  does affect software reuse levels

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Q10 Do legal problems inhibit reuse?

• Legal issues e.g.. regarding contracting,
  ownership are still unresolved and are thought to
  be a serious impediment to reuse
• The statement
• I am inhibited by possible legal problems.
• Most respondents (68) report that legal problems
  do not appear to be an impediment
• Conclusion
• No significant correlation between levels of
  reuse and reported inhibition by legal problems.

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Q11 Does having a reuse repository improve code
reuse

• A reuse repository is a searchable collection of
  reusable assets.
• Slightly higher median for reuse levels for
  organizations with a repository
• Not statistically significant
• Conclusion
• Having a reuse repository does not improve reuse
• A repository should not be the focus for
  organizations trying to improve systematic reuse

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Q12 Is reuse more common in certain industries?

• Respondents were asked to classify their company
  or business
• Significant differences in reuse between
  different industries
• higher level for telecommunication
• lower level for aerospace industries
• Reasons not currently known
• Industries with low reuse might benefit from
  studying and adopting reuse practice in
  industries that lead in software reuse

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Q13 Are company, project sizes predictive of
organizational reuse?

• Small organizations
• Is systematic reuse a realistic goal given the
  the scope of their domain and limited resources?
• Large organizations
• Introducing systematic reuse may be unrealistic
  because of the large investment and time required
• No significant correlation were found between
  organizational size and reuse levels
• Conclusion
• Company and project size are not predictive of
  reuse levels
• Organizations of any size may succeed to
  introduce systematic reuse

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Q14 Are quality concerns inhibiting reuse?

• It is commonly thought software engineers
  distrust assets developed outside and thus are
  less likely to reuse them.
• No correlation between
• software developed elsewhere meets our
  standards
• what percentage of the parts you reuse are form
  external sources
• Experience in quality of reusable software have
  generally been favourable (69 agreement)
• No correlation between personal reuse level and
  experience in quality of external software
• Conclusion
• Satisfaction with quality does not influence
  reuse levels
• Does NOT mean that quality is unimportant

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Q15 Are organizations measuring reuse, quality,
and productivity?

• Measuring reuse is important to determine success
  of the reuse program
• Few organizations are currently measuring reuse
  (at most 25)
• Quality is more widely measured (42)
• Productivity measurement is relatively rare (32)
• Conclusion
• Many organizations do not measure reuse levels,
  quality, and productivity
• These organizations cannot properly manage their
  software processes and products, including reuse

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Q16 Does reuse measurement influence reuse?

• Measuring an activity will tend to increase it.
• Comparing median level of software reuse for
  organizations that are or are not measuring
  reuse.
• The study shows no correlation
• Conclusion
• Organizations that measure reuse do not use these
  measurements to improve reuse levels.

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How to improve reuse

• To improve systematic reuse concentrate on
• education about reuse
• developers understanding on the economic
  feasibility of reuse
• introduce a common development process that
  promotes reuse
• make high quality assets available to developers