Elements of Software Configuration Management

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Elements of Software Configuration Management
Edward H. Bersoff

• Presented by Diala T. Gammoh
• eel6883 Software Engineering II
• Dr. Damla Turgut

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Agenda

• Introduction
• SCM in Context
• The Elements of SCM- Software Configuration
  Identification - Software Configuration
  Control- Software Configuration Auditing-
  Software Configuration Status Accounting
• Conclusion
• My Opinion

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Introduction

• Software Configuration Management is one of the
  disciplines of the 1980s in response to the many
  failures in industry in 1970s, it has more focus
  on - the failures.
• - what went wrong and how we are going
  to correct it.
• - dissecting the software development
  process.
• - defining techniques by which it could be
  effectively managed.

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SCM in Context

• Product integrity is defined as the intrinsic set
  of attributes that characterize the product -
  that fulfills user functional needs- that can
  easily completely be traced through its life
  cycle- that meets specified performance- whose
  cost expectations are met- whose delivery
  expectations are met

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SCM in Context

• Software in this paper is defined as information
  that is- structured with logical and
  functional properties.- created and maintained
  in various forms and representations during
  life cycle.- tailored for machine processing
  in its fully developed state.

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SCM in Context

• Software is not simply a set of computer
  programs, but includes the documentation required
  to define, develop and maintain these programs.
  Here, it escapes the software development manager
  who assumes that controlling a software product
  is the same as controlling computer code.
• Developers structure themselves into three basic
  discipline sets includes project management,
  development and product assurance

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SCM in Context

• The project management discipline- supports
  general management needs to see whats going on
  in a project and to ensure that the
  organization develops product with integrity.-
  looks inside the project in support of the
  assignment, allocation and control of all
  project resources.- determines the relative
  allocation of resources to the set of
  development and product assurance disciplines.

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SCM in Context

• The development disciplines represent those
  traditionally applied to a software project
  include- Analysis- Design- Engineering-
  Production(coding)- Test(unit/subtesting)-
  Installation- Documentation- Training-
  Maintenance

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SCM in Context

• The product assurance disciplines which are used
  by project management to gain visibility into the
  development process include- Configuration
  Management- Quality Assurance- Validation and
  Verification- Test and Evaluation

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SCM in Context
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Product Assurance Configuration Management

• Configuration Management (CM) is the discipline
  of identifying the configuration of a system at
  discrete points in time for the purpose of
  systematically controlling changes to the
  configuration and maintaining the integrity and
  traceability of the configuration throughout the
  system life cycle.
• Software Configuration Management (SCM) is simply
  configuration management tailored to systems or
  portions of systems that are comprised of
  software.

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Product Assurance Quality Assurance

• Quality Assurance (QA) consists of the
  procedures, techniques, and tools applied by
  professionals to insure that a product meets or
  exceeds prespecified standards during a products
  development cycle.

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Product Assurance Quality Assurance

• QA discipline has not been uniformly treated or
  invoked relative to software development because
• 1- Very few organizations have software
  design and development standards that compare
  in any way with hardware standards for
  detail and completeness
• 2- It takes a high level of software
  expertise to assess whether a software
  product meet prescribed standards.

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Product Assurance Quality Assurance

• QA discipline has not been uniformly treated or
  invoked relative to software development
• 3- Few buyer organizations have
  provided for or have developed the capability
  to impose and then monitor software endeavors
  on seller organizations.
• 4- Few organizations have been concerned
  over precisely defining the difference
  between QA and other product assurance
  discipline.

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Product Assurance Validation and Verification

• Validation and Verification (VV)
• - The purpose is to cope with the software
  and its development.- Unlike QA which deals
  which the problem of a product adherence to a
  pre established standards, VV deals with the
  issue of how well software fulfills functional
  and performance requirement and the assurance
  that specified requirements are indeed stated
  and interpreted correctly.

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Product Assurance Validation and Verification

• Validation and Verification (VV)- Verification
  assures that a product meets its prescribed
  goals as defined through baseline
  documentation. It insures that the end-user
  gets the product right.- Validation assures
  that the product not only meets the objectives
  specified through baseline documentation, but
  in addition, does the right job. It insures
  that the end-user gets the right product.

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Product Assurance Test and Evaluation

• Test and Evaluation (TE) is defined as the
  discipline imposed outside the development
  project organization to independently assess
  whether a product fulfills objectives.
• The definitions given for CM, QA, VV, and TE
  suggest some overlap.
• There are those who believe that CM, VV are
  subsets of the QA and others who argue that VV
  and TE have come into being as separate
  disciplines because QA methods have failed to do
  an adequate job with respect to providing product
  assurance.

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The Elements of SCM

• SCM elements were chosen to be the same as those
  for hardware, the four components of SCM are-
  identification- control- auditing- status
  accounting

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The Elements of SCM

• Software Configuration Identification
• - Effective management of a system requires
  careful definition of its baseline
  components, changes to these components need
  to be defined.- A system baseline is like a
  snapshot of the aggregate of system
  components.- Updates to this baseline is like
  frames in a movie strip of the system life
  cycle.

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The Elements of SCM

• Software Configuration Identification
• - The role of software configuration
  identification in the SCM process is to provide
  labels for these snapshots and the movie
  strip.- A baseline can be characterized by two
  labels, one label for the baseline itself and
  the other label identifies the update to a
  particular baseline.- The most elementary
  entity in the software configuration
  identification is the software configuration
  item (SCI)

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The Elements of SCM

• Software Configuration Identification
• - From SCM perspective a software baseline
  appears as a set of SCIs.- The SCIs within a
  baseline are related to one another via a
  tree like hierarchy.- As the software system
  evolves through its life cycle, the number of
  branches in this hierarchy generally
  increases.- The first baseline may consist of
  no more than one SCI.

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The Elements of SCM

• Software Configuration Identification- The
  lowest level SCIs in the tree hierarchy may
  still be under development and not yet under
  SCM control.- These entities are termed
  design objects or computer program
  components. (Figure 3, page 13)- Each baseline
  and each member in the associated family of the
  updates will exist in one or more forms such as
  a design document, source code on a disk or
  executing object code.

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The Elements of SCM

• Software Configuration Identification- The
  identification of baselines and updates
  provides an explicit documentation trail
  linking all stages of the software life
  cycle.- With the aid of this documentation
  trail, the software developer can assess the
  integrity of his product, and the software
  buyer can assess the integrity of the product
  he is paying for.

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The Elements of SCM

• Software Configuration Control- The evolution
  of a software system, in the language of SCM,
  is the development of baselines and
  incorporation of a series of changes into the
  baselines.- In addition to these changes, there
  are changes that occur during early stages of
  the system life cycle that may affect baselines
  that do not yet exist.

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The Elements of SCM

• Software Configuration Control- The role of the
  software configuration control is to provide
  the administrative mechanism for preparing,
  evaluating, approving or disapproving all
  change proposal throughout the system life
  cycle. - SCC focuses on managing changes to
  SCIs (existing or to be developed) in all of
  their representations.

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The Elements of SCM

• Software Configuration ControlThis process
  involves 3 basic ingredients
• 1- Documentation administrative forms,
  supporting technical and administrative
  material.2- Configuration Control Board (CCB)
  organizational body for formally evaluating
  and approving or disapproving a proposed
  change to the system.3- Procedures for
  controlling changes to a software system.

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The Elements of SCM

• Software Configuration ControlThe Engineering
  Change Proposal (ECP) is a major control
  document, contains information such as- a
  description of the proposed change.-
  identification of the originating
  organization.- rationale for the change.-
  identification of the affected baselines and
  SCIs (if appropriate).- specification of cost
  and schedule impacts.Figure 5 page 14.

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The Elements of SCM

• Software Configuration ControlMany automated
  tools support the control process such as the
  PSLs (Program Support Libraries).
• - There are automation for other functions
  such as library access control, software and
  documentation version maintenance, change
  recording, and document reconstruction.-
  These capabilities are available in systems
  such as SOFTTOOLs change and configuration
  control environment.

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The Elements of SCM

• Software Configuration Control- PSL should
  support 3 main activities code development,
  software management, and configuration
  control.- A PSL provides the support for code
  development 1- storage and maintenance of
  software documentation and code. 2- support to
  program/compilation testing. 3- support
  for the generation of program/system
  documentation.

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The Elements of SCM

• Software Configuration ControlSupport to the
  management of the software development process
  involves the storage and output of programming
  data such as1- collection and automatic
  reporting of management data related to
  program development.2- control over the
  integrity and security of the data in the
  PSL.3- separation of the clerical activity
  related to the programming process.

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The Elements of SCM

• Software Configuration ControlPSL provides
  support to the configuration control process
  through1- access and change authorization
  control for all data in the library.2- control
  of software code releases.3- automatic program
  and document reconstruction.4- automatic
  change tracking and reporting.5- assurance
  of the consistency between documentation,
  code and listings.

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The Elements of SCM

• Software Configuration ControlA PSL has four
  major components1- internal libraries in
  machine-readable form.2- external libraries
  in hardcopy form.3- computer procedures.4-
  office procedures.

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The Elements of SCM

• Software Configuration Auditing- It provides
  the mechanism for determining the degree to
  which the current state of the software system
  mirrors the software system pictured in
  baseline and requirements documentation.- It
  also provides the mechanism for formally
  establishing a baseline.

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The Elements of SCM

• Software Configuration AuditingSCA serves two
  purposes1- Configuration Verification which
  ensures that what is intended for each
  software configuration item as specified in
  one baseline or update is actually achieve in
  the succeeding baseline or update.2-
  Configuration Validation which ensures that
  the SCI configuration solves the right
  problem.

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The Elements of SCM

• Software Configuration Auditing- SCA is
  intended to increase visibility and to
  establish traceability throughout the life
  cycle of the software product.- This visibility
  and traceability are not achieved without cost.
  It costs time and money.- The investment in
  time and money in the early stages of a project
  is worth it at the later stages like avoiding
  the sudden appearance of new requirements
  and discovery of major design flaws.

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The Elements of SCM

• Software Configuration Status Accounting - It is
  the administrative tracking and reporting of
  all software items formally identified and
  controlled.- It also involves the maintenance
  of records to support software configuration
  auditing.- It records the activity associated
  with the other three SCM functions and
  therefore provides the mans by which the
  history of the software system life cycle can
  be traced.

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The Elements of SCM

• Software Configuration Status Accounting The
  scope encompasses the recording and reporting
  of1- the time at which each representation of
  a baseline and update came into being.2- the
  time at which each SCI came into being.3-
  descriptive information about each SCI.4-
  engineering change proposal status (approved,
  disapproved, awaiting action).5- descriptive
  information about each ECP.6- change status.7-
  descriptive information about each change.8-
  status of technical and administrative
  documentation associated with a baseline or
  update.9- deficiencies in a to-be-established
  baseline uncovered during a configuration
  audit.

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The Elements of SCM

• Software Configuration Status Accounting Because
  of its large data input and output requirements,
  it is generally supported by PSL described
  earlier.

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Conclusion

• We must have the visibility and control that the
  product assurance disciplines have the capacity
  to provide.
• We must be careful not to overcompensate and over
  control, this is the fine line that will
  distinguish that successful software managers of
  the 1980s from the rest of the software
  engineering community

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My Opinion

• The paper was comprehensive.
• PSL (Program Support Libraries) was a good
  addition to the paper.
• I prefer if they mentioned some practical
  applications that use the PSL.