1. Configuration Management

2. Configuration Management
Real software systems are huge and involve many components, and multiple engineers working simultaneously on components. This raises many problems related to managing components and the work done on them.
Configuration management addresses these problems.

3. Definitions
Configuration: the constituent components of a software product (including all of its versions)
Configuration management: the discipline of coordinating software development and controlling the change and evolution of software products and components

4. Configuration Mgmt Problems
Sharing software-related artifacts
Support for product families
Providing mechanisms for overseeing change
Providing documentation

5. Configuration Mgmt Problems
Sharing software-related artifacts
Support for product families
Providing mechanisms for overseeing change
Providing documentation

6. Sharing Artifacts: Problems
Suppose you and I both want to modify stack.c
What if we just both go ahead?
How about if I physically take the file?
How about if we each make private copies of it?

7. Sharing Artifacts: Solutions
Make single writer, multiple reader the norm; provide for occasional controlled multiple updates (RCS)
Allow multiple writers (optimistic rather than pessimistic) but police checkins (CVS)
Either solution requires merge abilities
More difficult with dependencies
Sharing requires co-ordination of effort

8. Configuration Mgmt Problems
Sharing software-related artifacts
Support for product families
Providing mechanisms for overseeing change
Providing documentation

9. Product Families
Programs have components, which have versions and variants
Versions are new instances
Variants are concurrent instances
Versioning schemes help manage product families

10. An Example of Versioning
3.0.0
3.0.1
3.0.2
3.0.3 …
3.1.0
3.1.1
3.1.2
3.1.8
3.2.0
3.2.1
First digit: major version
Second digit: minor version
Third digit: bugfix version
4.0.0

11. An Example of Versioning
3.0.0
3.0.1
3.0.2
3.0.3 …
3.1.0
3.1.1
3.1.2
3.1.8
3.2.0
3.2.1
What challenges exist here?
4.0.0

12. Managing Product Families
Possible approaches:
Keep separate copy of all materials for each version and variant
Keep common code, with deltas for variants (how to manage this?)
Other issues:
What to keep under configuration management
Basic objects vs derived objects
When do we abandon versions?

13. Configuration Mgmt Problems
Sharing software-related artifacts
Support for product families
Providing mechanisms for overseeing change
Providing documentation

14. Overseeing Change
Imagine engineers just fixed things when they thought they needed to. What could happen?
Need: formal/rigorous processes for managing and monitoring changes

15. The Change Management Process
Request change by completing a change request form
Analyze change request
If change is valid then
Assess how change might be implemented
Assess change cost
Submit request to change control board
If change is accepted then
Repeat
Make changes to software
Submit changed software for quality approval
Until software quality is adequate
Create new system version
Else
Reject change request

16. Configuration Mgmt Problems
Sharing software-related artifacts
Support for product families
Providing mechanisms for overseeing change
Providing documentation

17. Documentation When systems change, who needs to know?
How do we manage this?

18. Change Request Form Project: Dejavu Number: 1436
Change requester: A. Kinneer Date: 08/16/2007
Requested changes: Postpone test suite union operation until all dangerous edges have been selected
Change analyzer: H. Do Analysis date: 08/24/2007
Components affected: SelectTests, EdgeCompare
Associated components: None
Change assessment: Requires change to interfaces to allow passing edge set, otherwise relatively simple and will improve efficiency.
Change priority: Medium
Estimated effort: 0.5 days
Date to CCB: 08/26/2007 CCB decision date: 09/10/2007
CCB decision: Accept change; implement in release 3.2
Change implementor: Date of change:
Date submitted to QA: QA decision:
Date submitted to CM:
Comments:

19. Configuration Mgmt Problems
Sharing software-related artifacts
Support for product families
Providing mechanisms for overseeing change
Providing documentation

20. CM Tools CVS: www.nongnu.org/cvs/ SVN: subversion.apache.org
A mature CM tool
SVN: subversion.apache.org
Built on CVS, better for distributed collaboration over the net
GIT: github.com
A web-based CM hosting site
TortoiseSVN: tortoisesvn.net
An SVN client that operates on Windows through Explorer

21. Questions to ask when Learning a Configuration Management System
How is sharing supported?
Policy for readers/writers?
How to check things out?
How to check things in?
How to check for conflicts?
How to add/delete items?
How to get started?
How are merges handled?

22. Questions to ask when Learning a Configuration Management System
How are product families supported?
What versioning scheme is used?
How to mark releases?
Documentation support?
What is required for transactions?
What info is available to maintainers?
Process support?
What processes are supported or assumed?
Policy for readers/writers?

23. Example: CVS command-line commands
CVS help
CVS import
CVS checkout
CVS commit
CVS update
CVS log
CVS diff
CVS remove
CVS add
Print basic info on CVS commands
Import sources into CVS
Checkout sources for editing
Check files into the repository
Bring workspace & repository into sync
Print history information for a file
Show differences between revisions
Remove an entry from the repository
- Register a new entry for addition