1. Chapter 11: Software Configuration Management
Asst. Prof. Dr. Duygu Çelik Ertuğrul

2. Configuration Management
New versions of software systems are created as they change
Configuration management is concerned with managing evolving systems
Involves the development of procedures and standards to manage product evolution
May be viewed as part of a more general quality management process.

3. Software Configuration Management (SCM)
A Software Configuration Management (SCM) Plan defines the strategy to be used for change management.

4. Software Configuration Management
How to manage ‘change’ in software ?
SE Process produces three main categories of outputs:
Computer programs
both source and executable
Documentation
both technical and user
Data
within a program or external to it
These items are called a ‘software configuration’.

5. Fundamental sources of change (in software configuration)
New business or market conditions may dictate changes in requirements or business rules.
Customers may ask for modification of:
Data produced
Functionality delivered
Services delivered by a computer program
Reorganization or change of business size (↗ or ↘) may cause changes in project priorities.
Budgeting or scheduling constraints may cause a redefinition of the system to be built
Errors detected in the software need to be corrected

6. Software Configuration Management?
A set of activities that have been developed to manage change throughout the life cycle of computer software.
Change is a ‘fact of life’ in SE.
Customers want to modify requirements,
Developers want to modify technical approach,
Managers want to modify project approach,
as they get more experienced, and collect additional info.

7. Configuration Management Standards
CM should always be based on a set of standards which are applied within an organization
Should define how
items are identified
changes are controlled
versions are managed
Should be based on an evolutionary process model rather than something like the waterfall model!!!

8. Baselines
A work product becomes a baseline only after it is reviewed and approved.
A baseline is a software configuration management concept that helps us to control change without seriously approaching justifiable change.
Once a baseline is established each change request must be evaluated and verified by a formal procedure before it is processed.

9. Fig 9.2. Baselined SCIs and Project Database (Software Repository or Project Library)

10. SUMMARY: A Baseline: (IEEE Std. 610. 12_1990)
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.
Before a software configuration item becomes a baseline, changes may be made quickly and informally.
Once a baseline is established, changes can only be made by applying formal procedures
Milestones usually define baselines.
The progress of events that lead to a baseline is illustrated in the previous slide
Purpose of creating Baseline?
Creation of a baseline is usually a milestone in the schedule.
The baseline is centrally controlled.
Everyone uses the same current baselines.
To change the baseline, a formal process is required.

11. Software Configuration Item (SCI)
Definition: Information that is created as part of the software engineering process.
Examples:
Software Project Plan
Software Requirements Specification
Models, Prototypes, Requirements
Design document
Source code
Test suite
Software tools (e.g., compilers)

12. A Software Configuration Item ?
The following SCI-Software Configuraion Items become the target for configuration management techniques, and hence form a set of baselines:
7. Test specification
Test plan and procedure
Test cases and recorded results
8. Operation and installation manuals
9. Executable program
Module executable codes
Linked modules executable codes
10. Database description
Scheme and file structure
Inıtıal content
User manual
Maintenance documents
Software problem reports
Maintenance requests
Engineering change orders
Standards and procedures for SE
1. System Specification
2. Software Project Plan
3. Software Requirement Specification
Graphical analysis model
Process specifications
Prototype(s)
Mathematical specification
4. Preliminary User Manual
5. Design specification
Data design description
Architectural design description
Module design descriptions
Interface design descriptions
Object descriptions
6. Source code listing
A Software Configuration Item ?
Information that is created as a part of the SE process (a document, an entire plan of test cases, or a program module)

13. Many companies also place specific versions of editors, compilers, and other CASE tools under configuration control.
A configuration object has a name, attributes and connections to other configuration objects.

15. Elements of SCM There are four elements of SCM:
Software Configuration Identification
Software Configuration Control
Software Configuration Auditing
Software Configuration Status Accounting

16. Configuration Management Cycle
Customer
Customer generates
a change request
Customer approves changes
Project Manager
Manager assigns change request to software engineer
Dev Team
Software engineer checks out necessary configuration objects
SE checks in modified configuration objects and notifies CM
SE completes necessary changes
Configuration
Manager*
CM prepares new system release for operation if necessary
CM creates new system baseline
*In charge of administering project database and providing access control to engineers

17. Software Configuration Management Tasks
Identification (tracking multiple versions to enable efficient changes)
Version control (control changes before and after release to customer)
Change control (authority to approve and prioritize changes)
Configuration auditing (ensure changes made properly)
Reporting (tell others about changes made)

18. Requirements for SCM
Repository: shared DB for artifacts (eserler) with controlled access to prevent overwrites.
Version management: Preserve history of changes made to each artifact; provide ability to see how version was created.
Workspace control: Private work space with ability to check out from repository and check in with new version number.
Product modeling and building: Procedure to build the product from artifacts in repository.

19. Version Numbering Derivation Structure from Sommerville
Version Terminology
Version
instance of system that is functionally different from other system instances
Variant
instance of system that is functionally identical but non-functionally different from other system instances.
Release
system instance distributed to users outside the development team.
Version Numbering Derivation Structure from Sommerville

20. Change Tracking Tools
Major problem in change management is tracking the change status
Change tracking tools help track the status of each change request
Ensures that change requests are sent to the right people at the right time
Can be integrated with systems to allow electronic distributions of change requests

21. According to
IEEE Standard standard for
Software Configuration Management Plans
CM Plan - Format
1. Introduction a) purpose b) scope c) definitions and acronyms d) references 2. Management a) organization b) SCM responsibilities c) interface control d) SCMP implementation e) policies, directives, procedures (naming conventions, version designations, problem report process) 3. SCM Activities a) configuration identification b) configuration control (change history, review authority, read/write control, member identification) c) configuration status accounting (status of requests, status of approved changes, …) d) audits and reviews 4. Tools, Techniques, and Methodologies 5. Supplier Control 6. Records Collection and Retention

22. IEEE 1042 Guide to Software Configuration Management
Defines terms, such as baseline and version
Discusses configuration management as a management discipline and its role in the engineering process
Includes checklists of issues for sections of the SCMP (IEEE Std 828)
Includes four complete examples of SCMPs

23. CM Tools - Necessary Features
Dependency Tracking!!!
Audit Trails!!!
Reporting of Changes
Supports the Change Rules
Versioning
Requirements Tracing
Repository arranged as "basic objects" and "aggregate objects"
Supports both Linear evolution and Trees