Configuration Management Ref: Pressman chapter 9 EEE493 2000

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Configuration Management Ref Pressman chapter
9EEE493 2000
Royal Military College of Canada Electrical and
Computer Engineering

• Major Greg Phillips
• greg.phillips_at_rmc.ca
• 1-613-541-6000 ext. 6190

Dr. Scott Knight knight-s_at_rmc.ca 1-613-541-6000
ext. 6190
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Software Engineering

• Dave Parnass definition
• The multi-person production of multi-version
  software
• What does this imply?

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What can go wrong?

• a difficult bug that was fixed at great expense
  suddenly reappears
• a developed and tested feature goes missing
• a fully tested program suddenly doesnt work
• two programmers are working simultaneously on a
  program the second one to make changes destroys
  the work of the first
• a bug is fixed in code shared by several
  programmers some of them arent notified
• a program is being developed in several
  concurrent versions (one in use, one in test, one
  in development) a bug is fixed in one version
  but not the others

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Configuration Management

• The art of coordinating software development to
  minimize confusion is called configuration
  management. Configuration management is the art
  of identifying, organizing, and controlling
  modifications to the software being built by a
  programming team. The goal is to maximize
  productivity by minimizing mistakes.
• Babitch 1986

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Key requirements of a CM system

• What is my current configuration?
• What is its status?
• How do I control changes?
• How do I inform everyone else of changes?
• What changes has anyone else made to my
  configuration?
• Do anyone elses changes affect my configuration?

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Basic CM Functions

• configuration control
• ensuring there is only one official
  configuration, and that this is well known to all
  developers
• revisions
• tracking and being able to reconstruct every
  change that was ever made to any product
• versions
• tracking the relationships between multiple
  versions of the same system (e.g., the normal
  version and the version for restricted memory
  systems)
• implementing deltas
• efficiently storing the multiple revisions and
  versions

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Configuration Control Baselines

• A specification or product that has been formally
  reviewed and agreed upon, that thereafter serves
  as the basis for further development, and that
  can be changed only through formal change control
  procedures.
• IEEE Standard 610
• Key idea
• a baseline represents the one official copy
• once a specification or product has been
  established as a baseline, it can only be changed
  with the formal approval of the responsible
  stakeholders
• approval authority will depend on the project
  culture, the phase of development, and the
  maturity of the product

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CM Process
Initial development
Requirements/ design/use
Establish/ update baseline
Approve change
Validate baseline
Authorize change
Implement change
Validate change
Baselines
Changes
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Revisions

• need to be able to reconstruct the exact revision
  level of any product, at any time
• Consider a failed test. To recreate, may need
  exact revisions of
• hardware
• operating system
• product under test
• supporting products
• test harnesses and drivers
• test procedures
• also assists with many simpler functions
• Make a misguided change that destroys existing
  functionality must be able to revert to previous
  revision

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Differences

• it was working yesterday
• must be able to identify differences between
  revisions
• what change is
• who made change
• when change was made
• purpose of change
• improves debugging effectiveness
• provides audit trail, accountability

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Versions

• often several related versions of a single
  product
• production, development, design
• Windows, Mac, Solaris, Linux
• large memory version, small memory version
• to modify effectively, must understand
• which products are common across versions
• which products are unique to versions
• how they are related (e.g., for multi-version
  debugging)

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Deltas

• maintaining complete copies of all versions and
  revisions bulky
• where revisions/versions close, can often store
  just deltas
• frequently used in configuration management tools
  to reduce storage requirements
• typically works well only for textual information
• occasionally desirable to flatten deltas and
  store actual product in the repository

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