1. Configuration Management
Main issues:
manage items during software life cycle
usually supported by powerful tools

2. Some Simple CM Scenarios
Developer A wants to see latest version of foo.c and its change history since last week
B needs to revert foo-design.doc to its version two days ago
B makes a release of the project and he needs to know what items to include and which version

3. Some Simple CM Scenarios (cont.)
A lives in New Delhi, India and B lives in Boston, US, they want to work on HelloWorld.java together
In the latest release, a serious bug is found and manager C wants to track
what changes caused the bug,
who made those changes and
when
C wants to get reports about current project progress to decide if she needs to hire more programmers and delay the alpha release

4. Configuration Item (CI) Version, Variant, and Revision Configuration
SCM Terminology
Configuration Item (CI)
Version, Variant, and Revision
Configuration
Baseline
Workspace

5. Configuration Item (CI)
An approved and accepted deliverable, changes have to be made through formal procedure
Examples:
Management plan
Requirement
Design specification
Source code and executable code
Test specification, data, and records
Log information
User documentation
Library and supporting software
Bug reports, etc.

6. Version, Variant, and Revision
Version: a CI at one point in its development, includes revision and variant
Revision: a CI linked to another via revision-of relationship, and ordered in time
Variant: functionally equivalent versions, but designed for different settings, e.g. hardware and software
Branch: a sequence of versions in the time line
1.2
1.3
1.4
Win32 on x86
Solaris on SPARC
1.2
1.3
1.4

7. How Versions are Stored
Full copy of each version
Delta (differences between two versions)
Forward delta
Reverse delta
Mixed delta
1.1
1.2
1.3
1.4
1.1
1.2
1.3
1.4

8. Baseline
A collection of item versions that have been formally reviewed and agreed on, a version of configuration
Marks milestones and serves as basis for further development
Can only be changed via formal change management process
Baseline + change sets to create new baselines

9. Workspace
An isolated environment where a developer can work (edit, change, compile, test) without interfering other developers
Examples
Local directory under version control
Private workspace on the server
Common Operations
Import: put resources into version control in repository
Update: get latest version on the default branch
Checkout: get a version into workspace
Checkin: commit changes to the repository

10. Configuration An arrangement of functional CIs according to their
nature,
version and
other characteristics
Guaranteed to recreate configurations with quality and functional assurance
Sometimes, configuration needs to record environment details,
e.g. compiler version, library version, hardware platform, etc.
Simple examples
Ant buildfile, Makefile

11. Configuration Control Board
ensures that every change to the baseline (change request - CR) is properly authorized and executed
CCB needs certain information for every CR, such as who submits it, how much it will cost, urgency, etc
CCB assesses the CR. If it is approved, it results in a work package which has to be scheduled.
so, configuration management is not only about keeping track of changes, but also about workflow management
SE, Configuration Management, Hans van Vliet, ©2008

12. Configuration management tasks
identification and definition of configuration items, such as source code modules, test cases, requirements specification
managing changes and making configuration items available during the software life cycle, usually through a Configuration Control Board (CCB)
keeping track of the status of all items (including the change requests)
crucial for large projects
SE, Configuration Management, Hans van Vliet, ©2008
© SE, Configuration Management, Hans van Vliet

13. General Workflow of a change request
change request (CR)
investigate
notify owner
reject
approve
schedule work
request info
defer
implement change
SE, Configuration Management, Hans van Vliet, ©2008

14. Tool support for configuration management
if an item has to be changed, one person gets a copy thereof, and meanwhile it is locked to all others
new items can only be added to the baseline after thorough testing
changes in the status of an item (e.g. code finished) trigger further activities (e.g. start unit testing)
old versions of a component are kept as well, resulting in versions, like X.1, X.2, …
we may even create different branches of revisions: X.2.1, X.2.2, … and X.3.1, X.3.2, ...
SE, Configuration Management, Hans van Vliet, ©2008

15. Functionalities of SCM tools
Components (storing, retrieving, accessing, …)
Structure (representation of system structure)
Construction (build an executable)
Auditing (follow trails, e.g. of changes)
Accounting (gather statistics)
Controlling (trace defects, impact analysis)
Process (assign tasks)
Team (support for collaboration)
SE, Configuration Management, Hans van Vliet, ©2008

16. Models of configurations
version-oriented: physical change results in a new version, so versions are characterized by their difference, i.e. delta
change-oriented: basic unit in configuration management is a logical change
identification of configuration becomes different: “baseline X plus fix table bug” instead of “X Y2.7 + Z3.5 + …”
SE, Configuration Management, Hans van Vliet, ©2008

17. Version Control Models (1/3)
Basic problem of collaborative work
Figure from svn-book

18. Version Control Models (2/3)
Model 1-Pessimistic: lock-modify-unlock
Problems:
Forget to unlock
Parallel work not possible
Deadlock
Figure from svn-book

19. Version Control Models (3/3)
Model 2-Optimistic: copy-modify-merge
Figure from svn-book

20. Change control process Status accounting Configuration audit
SCM Processes
Change control process
Status accounting
Configuration audit
Release management
CM planning

21. Change Control Process
Submission of Change Request (CR)
Technical and business evaluation and impact analysis
Approval by Change Control Board (CCB)
Engineering Change Order (ECO) is generated stating
changes to be made
criteria for reviewing the changed CI
CI’s checked out
Changes made and reviewed
CI’s checked in

22. Status Accounting
Administrative tracking and reporting of CIs in CM system
Examples
Status of proposed changes
Status of approved changes
Progress of current version, on or behind schedule
Estimate of resources to finish one task
bugs identified by configuration audit

23. Configuration Audit
Independent review or examination to assess if a product or process is in compliance with specification, standards, contractual agreement, or other criteria
Examples
Verifies that CIs are tested to satisfy functional requirements
Verifies that baseline contains necessary and correct CI versions
Ensures that changes made to a baseline comply with the configuration status reports

24. The change management process
Change Request Form
Project: SICSA/AppProcessing Number: 23/02
Change requester: I. Sommerville Date: 20/01/09
Requested change: The status of applicants (rejected, accepted, etc.) should be shown visually in the displayed list of applicants.
3:06 PM
Chapter 25 Configuration management

25. A partially completed change request form (a)
Project: SICSA/AppProcessing Number: 23/02
Change requester: I. Sommerville Date: 20/01/09
Requested change: The status of applicants (rejected, accepted, etc.) should be shown visually in the displayed list of applicants.
Change analyzer: R. Looek Analysis date: 25/01/09
Components affected: ApplicantListDisplay, StatusUpdater
Associated components: StudentDatabase
3:06 PM
Chapter 25 Configuration management

26. A partially completed change request form (b)
Change assessment: Relatively simple to implement by changing the display color according to status. A table must be added to relate status to colors. No changes to associated components are required.
Change priority: Medium
Change implementation:
Estimated effort: 2 hours
Date to SGA app. team: 28/01/09 CCB decision date: 30/01/09
Decision: Accept change. Change to be implemented in Release 1.2
Change implementor: Date of change:
Date submitted to QA: QA decision:
Date submitted to CM:
Comments:
3:06 PM
Chapter 25 Configuration management

27. Release Management
Creation and availability of a new version of software to the public
Release format
Source code + build script + instructions
Executables packaged for specific platforms
Other portable formats: Java Web Start, plugins
Patches and updates: automatic, manual
Release content
Source and/or binary, data files, installation scripts, libraries, user and/or developer documentation, feedback programs, etc.

28. Make a CM Plan Standards CM plan components
IEEE Std 828 (SCM Plans), ANSI-IEEE Std 1042 (SCM), etc.
CM plan components
What will be managed (list and organize CIs)
Who will be responsible for what activities (roles and tasks)
How to make it happen (design processes for change requests, task dispatching, monitoring, testing, release, etc.)
What records to keep (logs, notes, configurations, changes, etc.)
What resources and how many (tools, money, manpower, etc.)
What metrics to measure progress and success

29. CM Tools Version control Bug tracking Build Project management
RCS, CVS, Subversion, Visual Source Safe, Rational ClearCase
Bug tracking
Bugzilla, Mantis Bugtracker, Rational ClearQuest
Build
GNU Make and many variants, Ant
Project management
Sourceforge.net, freshmeat.net, GForge, DForge

30. Configuration Management Tasks
Identification
tracking changes to multiple SCI versions
Version control
controlling changes before and after customer release
Change control
authority to approve and prioritize changes
Configuration auditing
ensure changes are made properly
Reporting
tell others about changes made

31. Version Control Terms Entity Variant New version
composed of objects at the same revision level
Variant
a different set of objects at the same revision level and coexists with other variants
New version
defined when major changes have been made to one or more objects

32. Version identification
Procedures for version identification should define an unambiguous way of identifying component versions.
There are three basic techniques for component identification
Version numbering;
Attribute-based identification;
Change-oriented identification.

33. Version numbering Simple naming scheme uses a linear derivation
V1, V1.1, V1.2, V2.1, V2.2 etc.
The actual derivation structure is a tree or a network rather than a sequence.
Names are not meaningful.
A hierarchical naming scheme leads to fewer errors in version identification.

34. Version derivation structure

35. Attribute-based identification
Attributes can be associated with a version with the combination of attributes identifying that version
Examples of attributes are Date, Creator, Programming Language, Customer, Status etc.
This is more flexible than an explicit naming scheme for version retrieval; However, it can cause problems with uniqueness - the set of attributes have to be chosen so that all versions can be uniquely identified.
In practice, a version also needs an associated name for easy reference.

36. Attribute-based queries
An important advantage of attribute-based identification is that it can support queries so that you can find ‘the most recent version in Java’ etc.
The query selects a version depending on attribute values
AC3D (language =Java, platform = XP, date = Jan 2003).

37. Change-oriented identification
Integrates versions and the changes made to create these versions.
Used for systems rather than components.
Each proposed change has a change set that describes changes made to implement that change.
Change sets are applied in sequence so that, in principle, a version of the system that incorporates an arbitrary set of changes may be created.

38. Change Control Process - 1
Change request is submitted and evaluated to assess its technical merit and impact on the other configuration objects and budget
Change report containing the results of the evaluation is generated
Change control authority (CCA) makes the final decision on the status and priority of the change based on the change report

39. Change Control Process - 2
Engineering change order (ECO) is generated for each change approved
ECO describes the change, lists the constraints, and criteria for review and audit
Object to be changed is checked-out of the project database subject to access control parameters for the object
Modified object is subjected to appropriate SQA and testing procedures

40. Change Control Process - 3
Modified object is checked-in to the project database and version control mechanisms are used to create the next version of the software
Synchronization control is used to ensure that parallel changes made by different people don’t overwrite one another

41. Configuration Management Team
Analysts.
Programmers.
Program Librarian.

42. Change Control Board
Changes should be reviewed by an external group who decide whether or not they are cost-effective from a strategic and organizational viewpoint rather than a technical viewpoint.
Should be independent of project responsible for system. The group is sometimes called a change control board.
The CCB may include representatives from client and contractor staff.
Customer representatives.
Some members of the Configuration management team.

43. Problem is reported to configuration control board.
Programmer’s View - 1
Problem is discovered.
Problem is reported to configuration control board.
The board discusses the problem
is the problem a failure?
is it an enhancement?
who should pay for it?
Assign the problem a priority or severity level, and assign staff to fix it.

44. Programmer files a change report documenting all changes made.
Programmer’s View - 2
Programmer or analyst
locates the source of the problem
determines what is needed to fix it
Programmer works with the librarian to control the installation of the changes in the operational system and the documentation.
Programmer files a change report documenting all changes made.

45. Change Control Issues
Synchronization (when?)
Identification (who?)
Naming (what?)
Authentication (done correctly?)
Authorization (who O.K.’d it?)
Routing (who’s informed?)
Cancellation (who can stop it?)
Delegation (responsibility issue)
Valuation (priority issue)

46. Software Configuration Audit - 1
Has the change specified by the ECO been made without modifications?
Has an FTR been conducted to assess technical correctness?
Was the software process followed and software engineering standards applied?
Engineering change order
formal technical review

47. Software Configuration Audit - 2
Do the attributes of the configuration object reflect the change?
Have the SCM standards for recording and reporting the change been followed?
Were all related SCI's properly updated?

48. Configuration Status Report
What happened?
Who did it?
When did it happen?
What else will be affected by the change?
Reference
Introduction to Configuration Management, lecture slides for COMP3100/3500, Ian Barnes, the Australian National University.
Software Configuration Management, Center for Development of Advanced Computing, Mumbai at Juhu, India.
Concepts in Configuration Management Systems, Susan Dart, CMU.
Software Configuration Management: A Roadmap, Jacky Estublier, CNRS, France.
Further Reading
Software Engineering, a Practitioner’s Approach (6th), part 4, Roger Pressman.
Code Complete (2nd), Steve McConnel.
Implementing and Integrating PDM and SCM, Ivica Crnkovic et al.
Version Control with Subversion, Ben Collins-Sussman et al.

50. Evolution of SCM tools Early tools: emphasis on product-oriented tasks
Nowadays: support for other functionalities too. They have become a (THE) major tool in large, multi-site projects
Agile projects: emphasis on running system: daily builds
SE, Configuration Management, Hans van Vliet, ©2008

51. Configuration Management Plan
Management section: organization, responsibilities, standards to use, etc
Activities: identification of items, keeping status, handling CRs
SE, Configuration Management, Hans van Vliet, ©2008

52. Summary
CM is about managing al kinds of artifacts during software development
Crucial for large projects
Supported by powerful tools
SE, Configuration Management, Hans van Vliet, ©2008