1. Configuration Management
CS 330 Introduction to Software Engineering
By Rania Elnaggar
West Virginia University

2. Outline The Law of Change What is Software Configuration Management
Identifying configuration Items
Version Control
Change Control
Configuration Audit
Status Reporting
CS 330 – Configuration Management - Slide 2

3. The Law of Change
Change is inherent in the nature of the entire universe
The only thing that doesn’t change is Change itself!
Software is more susceptible to change
Ease of changing software rapidly.
CS 330 – Configuration Management - Slide 3

4. What is Software Configuration Management?
Configuration Management is the art of identifying, organizing, and controlling modifications to the software being built by a team.
Four basic SCM steps:
Identify change
Control change
Ensure change is being properly implemented
Report change
CS 330 – Configuration Management - Slide 4

5. The Software Configuration
programs
documents
The pieces
data
CS 330 – Configuration Management - Slide 5

6. Software Configuration Items
Software consists of: programs, documents, and Data
The items that comprise all information produced as part of the software process are called SCIs.
CS 330 – Configuration Management - Slide 6

7. What are the changes? changes in business requirements changes in
technical requirements
changes in
user requirements
other
documents
software models
Project
Plan
data
Test
code
CS 330 – Configuration Management - Slide 7

8. Baselines A baseline is:
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.
CS 330 – Configuration Management - Slide 8

9. What is SCM? SCM Software Engineering • identification
tools
• version control
methods
• change control
procedures
• auditing
a TQM foundation
• reporting
CS 330 – Configuration Management - Slide 9

10. Identification of SCIs

11. Identification of SCIs
Identify entities:
Project plan
Overall Design Specification
Design Specification of individual Components
Test Specifications
etc
Identify relationships between entities
Assess the impact of change
CS 330 – Configuration Management - Slide 11

12. Version Control

13. Software versions
Every module exists in three forms
Source code
object code
executable load image
Configuration - given version of a product built by specific versions of each module
CS 330 – Configuration Management - Slide 13

14. Software Versions
During maintenance, at all times there are at least two versions of the product:
The old version, and
The new version
Two types of versions
Version
Variation
Revision
CS 330 – Configuration Management - Slide 14

15. Revisions
Revision
Version with fixed faults in the module
Should we throw away an incorrect version ?
Perfective and adaptive maintenance also results in revisions
It is vital to have control to ensure that every member of the development team knows which version is the current version of a given module
Each revision is written
to replace its predecessor
CS 330 – Configuration Management - Slide 15

16. Variations Variation Variations are designed to coexist in parallel
Version for different operating system or hardware
Variations are designed
to coexist in parallel
To complicate matters further, in general, there will be multiple revisions of each variation
CS 330 – Configuration Management - Slide 16

17. Version Control Tool
Which revision of which variation went into the version of of the product?
AcknowledgeMessage /1
AcknowledgeMessage /2
AcknowledgeMessage /3
AcknowledgeMessage /4
PrinterDriver (InkJet)
PrinterDriver (laser) /1
PrinterDriver (laser) /2
PrinterDriver (laser) /3
CS 330 – Configuration Management - Slide 17

18. Version Control Tool (contd)
First step toward version control is detailed record of every version of the product
Name of each source code element, including the variation and revision
Versions of various compilers and linkers used
Name(s) of the person(s) who constructed the product
Date and time at which it was constructed
Problem of multiple variations
Delta - list of differences from the original variation
Version control is not enough
CS 330 – Configuration Management - Slide 18

19. Version Control - Baselines
Problem - Two programmers working on the same module fixing two different faults
Solution - Baselines
Check out the module into private workspace
Freeze the current version of the module
New version is checked-in modifying the baseline
Configuration control during implementation and integration phase
CS 330 – Configuration Management - Slide 19

20. Build Tools At least build tool + version control tool
Example - UNIX tool make
For each executable load image the developer sets up Makefile specifying the hierarchy of source and object files that go into that particular configuration
Make compares the date and time stamp on
Source file, object file
Executable load image, every object file
Ensures that latest versions are compiled and linked
CS 330 – Configuration Management - Slide 20

21. Change Control
STOP

22. Change Control Process—I
need for change is recognized
change request from user
developer evaluates
change report is generated
change control authority decides
request is queued for action
change request is denied
user is informed
change control process—II
CS 330 – Configuration Management - Slide 22

23. Change Control Process-II
assign people to SCIs
check-out SCIs
make the change
review/audit the change
establish a “baseline” for testing
change control process—III
CS 330 – Configuration Management - Slide 23

24. Change Control Process-III
perform SQA and testing activities
check-in the changed SCIs
promote SCI for inclusion in next release
rebuild appropriate version
review/audit the change
include all changes in release
CS 330 – Configuration Management - Slide 24

25. Configuration Audit

26. Auditing SCM Audit Change Requests SQA Plan SCIs
CS 330 – Configuration Management - Slide 26

27. Configuration Audit
Complements the formal technical review by assessing configuration objects for characteristics that are not generally considered in a review:
Have the change specified been made?
Have any additional modifications been made?
Has a formal technical review been conducted to ensure correctness?
Has the s/w process been followed? Standards applied?
Are the changes highlighted?
Have all related SCIs been updated?
CS 330 – Configuration Management - Slide 27

28. Status Reporting

29. Status Reporting Accounting system that creates entries for:
What happened?
Who did it?
When did it happen?
What else it affected?
CS 330 – Configuration Management - Slide 29

30. Status Accounting Status Accounting Reporting Change Change Reports
Requests
ECOs
SCIs
Status Accounting
Reporting
CS 330 – Configuration Management - Slide 30