Software Configuration
Management
“The only constant is change ...”
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Lecture Objectives
To understand the activities in managing
software changes
To identify the software configuration
items that needs to be managed
To describe the different tasks in software
configuration management
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What is S/w Configuration
Management?
SCM is the discipline for systematically
controlling the changes that take place
during development
Umbrella activity that is applied throughout
SE process
SCM is easier at the start of development
and gets more complex towards the end
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Sources of Change
New business or market conditions
New customer needs
Reorganisation and/or business
downsizing
Budgetary or scheduling constraints
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Main Elements of SCM
Identification
What are the configuration items?
Control
How changes should be controlled?
Status Accounting
What changes have been made?
Auditing
Is the system being built to satisfy the
needs?
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Software Configuration
Computer programs
Source code
Executable code
Documents that describe the computer
programs
For technical staff
For users
Data
Within the program and external to it
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Software Configuration
Item
A document or an artifact that is explicitly
placed under configuration control and
that can be regarded as a basic unit for
modification
Examples:
requirement documents
design document
code of a module
test plan
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Baselines Definition
IEEE definition:
“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”
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Baselines
A baseline is essentially a set of SCIs
The items have been reviewed, corrected,
and approved
Baselines should be used as reference
point
Baselines should only be changed through
formal procedures
Careful definition and control of different
baselines should be done
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Examples of Baselines
Functional baseline (requirements)
Design baseline
Product baseline (developed system)
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Configuration Control
Version control - procedures and tools to
manage different versions of configuration
objects
Change control - procedures and tools to
provide a mechanism for the control of
changes
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Version Control
Process of identifying and keeping track of
different versions and releases of a system
Procedures to ensure that different versions
of a system may be retrieved when
required and not accidentally changed
Version management is almost always
supported by automated tools
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Evolution Graph
Obj
1.0
Obj
1.1
Obj
1.4
Obj
2.0
Obj
2.1
Obj
1.2
Obj
1.1.1
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Obj
1.3
Obj
1.1.2
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Versions, releases &
variants
Version - an instance of a system that
differs from other instances
different functionality
performance
repair of system faults
Release - version that is distributed to
customers
Variant - sometimes used when
differences are small
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Change Control
Focuses on managing changes to the
different forms of the SCIs
Engineering change proposal - basic
document used for defining & requesting
for a change.
Configuration Control Board (CCB) is
responsible for configuration management
CCB evaluate proposal & approve/reject it
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Change Control Process
Need
for
change
Change
request
generated
Evaluation
Change
report
generated
Technical merits, Side effects
Overall impact, Project cost
Other
SCM
tasks
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Place on
queue
for change
Requestor
is informed
ECO
generated
Approve
CCA
decision
Reject
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Engineering Change
Proposal
proposed change
reason(s)
baselines & SCIs that are affected
cost
schedule impacts
procedures for the change
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Engineering Change
Order
Change description
Constraints
Audit review criteria
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Change Process
Object to be changed is “checked out”
Change is made
Appropriate SQA activities applied
Object is “checked in” to the database
Version control mechanisms applied for
next version
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Change Process
Diagram
Configuration object
(modified version)
Audit info
Software
Engineer
Check-in
unlock
Access
control
Configuration object
(baseline version)
Ownership
info
Project
Database
lock
Configuration object
(extracted version)
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Configuration object
(baseline version)
Check-out
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Status
Accounting/Reporting
Keeps record of how the system evolves
and what is its current status
(administrative nature)
Can be complex due to the existence of
executable and non-executable forms
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Status Reporting
Process
Configuration
Identification
Configuration
Control
SCIs
Changes
Configuration
Audit
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CSR
Database
Status
Reporting
Deficiencies
CSR
Report
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Status Accounting
Tasks
Record baseline establishment time
Record when SCI came into being
Information about each SCI
Engineering change proposal status
Status of the approved changes
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Configuration Audit
Concerned with determining how
accurately the current software system
implements the system defined in the
baseline & requirements document
Also concerned with increasing the
visibility and traceability of the software
Also establish a new baseline
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Auditing
How do we know a change is properly
implemented?
Formal technical reviews - assess the SCI to
determine consistency with other SCIs
Software configuration audit
SCI changes made?
FTR conducted?
SE standards followed?
SCM procedures followed & updates properly done?
Related SCIs updated?
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References
“Software Engineering: A Practitioner’s
Approach” 5th Ed. by Roger S. Pressman,
Mc-Graw-Hill, 2001
“Software Engineering” by Ian Sommerville,
Addison-Wesley, 2001
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