Software Configuration Management

(SCM)[1.0]

VOYAGER

L&T Information Technology Ltd.

Contents

Characteristics of Today’s Software industry

SCM Concepts and terminology

Why Software configuration management?

Requirements of Configuration management

Standard reports

Typical Uses of SCM

The Fundamental Law of Configuration Management

Configuration Management is the foundation of a software project. Without it, no matter how talented the staff, how large the budget, how robust the development and test processes, or how technically superior the development tools, project discipline will collapse and success will be left to chance. Do Configuration Management right, or forget about improving your development process.

Why did the Tower of Babel fail?

The Tower of Babel project failed because of lack of communication and organization

Today's Software industry characteristics

are..

Characteristic 1 -

Coordination & Communication

Men and months cannot be interchanged

Fred Brooks

• Number of communication channels increase exponentially with number of team members - the number of coordination problems also increase exponentially with the project size.

Communication Channels

# Team Members #Communication Channels

1 0

2 1

3 3

4 6

5 10

….. …..

n n*(n-1)/2

Characteristic 2 -

Software is Easy to Copy

Characteristic 3 -

Changes

• Different users / customers have different requirements

• Get clarified / known at a later date

• Changes to business environment

• Technology change

• Personnel whims

Characteristic 4 -

Personnel Turnover

• Developers leave

• Users change

Further Adds to the Coordination problem

Resulting Problems

• Listing seems OK; program does not work

• Works in Bombay, misbehaves in Delhi

• We had customized for this client, how do we install the upgrade now?

• I had fixed this bug last month. How did it re-appear?

• I haven’t changed the program. Why is it now blowing up?

• Which is the latest source? I need to put a patch.

• In the last month, the user asked for this change and now she does not want it

• Where did Gates leave the programs he was working on?

Main Classes of Problems

• Double maintenance problems

• Shared data

• Simultaneous update

• Missing / unknown version problem

Double Maintenance

• Multiple copies of same software in use

• Fix in one

- SHOULD FIX IN OTHERS

• Example

- Same set of common routines in two systems

- Same system - multiple sites

• forget to inform

• sites detect bug at same time and “fix” differently

• = = > > DIVERGENCE

• Should do

- Bug fixed in all copies

- Fix same bug in identical manner in all copies

Shared Data

• Changes made in one program interfere with proper functioning of other program

- Example : subroutines, MW objects

• Need

- Control of modifications

- Good communications

Simultaneous Update

• One module being worked on by more than one programmer

- Changes made by one programmer disappear

• Need

- Better division into modules

- Ensure simultaneous working

Missing / unknown Version problem

• Consciously decide which version to keep, which to destroy

• Use a systematic method to identify versions and changes across versions

• Use consistent back-up procedures

?

Why Software Configuration Management

• SCM addresses all these issues!!

AbracadabAbracadabrara

SCM provides visibility into the status of the evolving software product.

SCM answers the following: Who, What, When, and Why.

• Who made the changes?

• What changes were made to the software?

• When were the changes made?

• Why were the changes made?

Who will benefit from SCM(Importance in descending order) :

• Software developers

• Project managers

• Quality Assurance (QA) personnel

• Testers

• Customer

Program Families & Configurations

A

D

E

B

C

F

A

CLIENT-1

DG

B

W

E

F

CLIENT-2

Applications

Applications

AD

E

B C

F

G W

CLIENT-A

A

B

C

D

E

F

CLIENT-B

A

B

D

E

F

G

W

Applications

SCMConcepts & Terminology

Definitions

The arrangement of a computer system or component as defined by the number, nature, and interconnections of its constituent parts

Configuration

The art of identifying, organizing and controlling modifications to the software being built by a programming team. The goal is to maximize productivity by minimizing mistakes.

Configuration Management

Configuration Management

Configuration Identification

The approved documentation or description that identifies and defines a configuration item's (CI) functional and physical characteristics in the form of a specification or standard, algorithm or code, and interface control description.

A

BC

D

Configuration Control

• Evaluation, coordination, approval or disapproval, and implementation of changes to configuration items after formal establishment of their configuration identification

Configuration Status Accounting

• Recording and reporting of information needed to manage a configuration effectively. Includes a listing of the approved configuration identification, the status of the proposed changes to the configuration identification, and the implementation status of approved changes.

CI = 30

CR = 2

PR = 1

Configuration Audit

• Verifying the following:

•All required configuration items have been produced

•The current version agrees with the specified requirements

•The technical documentation completely and accurately describes that configuration items

•All change requests have been resolved

Requirements of Configuration Management

CM Requirements

• Identification of Configuration Items

• Establishment of Baselines

• Document control

• Version control

• Management of Workspaces

• Creation of Builds

• Backup & Archival

• Management of Changes to Baselined Configuration Items

• Status Accounting

• Configuration Audits

Configuration Items and Baselines

• Configuration Item

- An aggregation of software, documents and data that is treated as a single entity in the configuration management process

There are 3 types of CIs:

Baselined – Formally reviewed and agreed document/source code, which is basis for, further development. E.g. Requirement specification document, design document etc.

Controlled and Managed – Documents describing the admin and project Management activities. E.g. Project management plan, task allocation and project schedule documents, coding or GUI guidelines

Controlled – Documents obtained from the customer which are not managed by us. E.g. reference technical material.

• What is Baseline?

- A item 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 procedures

Configuration Items & Baselines - Typical Scenario

• Definition Baseline - Created at the end of Requirement Specifications. Typical configuration items (CI) -

- Requirement Specifications

- Project Plan

- Design Standards / Guidelines

- Acceptance Test Plan

• Design Baseline - Created at the end of Design. Typical CIs -

- System Design Specification

- Program Specification

- Data Base Design

- Coding Standards

- System Test Plan

- User Manual

- User Interface Standards

- Testing Standards

• Code / Unit Test Baseline - Created at the end of coding and unit. Typical configuration items (CI) -

- source code

- object code

- unit test data / scripts

• Testing Baseline - Created at the end of system testing . Typical CIs -

- System test data

- system test scripts

- operations manual

- installation manual

Definition Baseline Creation - A schematic

Individual workspaces

Internal review changes

Definition Baseline

Internal review Workspace

Customer Review Workspace

Formal change management procedures become applicable

Configuration Audit

Review Log

Review Log

Document control• Document Control procedure ensures the

traceability of all the documents.

It involves the following tasks: Defining the naming scheme. Updating Document Record List (DCR) of

the documents to reflect the changes and assigning of version and release nos.

Provides usage of the documents by giving access rights to different folders.

MyName is

Mr.Unique

Version• A variant of some artifact; later

versions of an artifact typically expand on earlier versions.

Version Control• Version Control ensures the ability to

reproduce any version of the software at any given time. It controls versions of source code, executables and documents .It provides version change history to ensure trace-ability.

A1

A2A3A4

An operational version of a system or part of a system that demonstrates a subset of the capabilities to be provided in the final product.

Work space management• Workspaces refer to ‘private’ areas

where developers can implement and test code in accordance with the project’s adopted standards in relative isolation from other developers.

• Uncertainty is the only certain in this world.

Why Backup?

Change Control

I can make the change directly in the baseline copy. Its just a one line change, so I don’t want to fool around with Change Request, check-out, check-in, etc

Change Control

• Record of changes

• Approval of change requests after analysing impacts (impact on retest & review, think it as another proposed)

• Maintaining of baselines

• Traceability between changes and change requests and vice versa

IEEE Definition

An element of configuration management, consisting of the evaluation, coordination, approval or disapproval, and implementation of changes to configuration items after formal establishment of their configuration identification

Change Management Process

Change request documented

Change request Evaluated

Change request reviewed for approval CCB approved

Change order prepared

Configuration items, tasks, QC required is documented

Configuration items checked out

Change made; QC activities carried out

Configuration audit carried out

Changed items carried out

New product release made

Pending rejected

Change Request

XYZ Software Corp. Change Request

Project: Initiated By: Date:

Description of Change Requested:

Benefits Expected:

Signature of Initiator: Attachments:

Evaluated by: Change Request No.

Technical Impacts:

Estimates for costs and schedule

Signature of evaluator: Attachments

Date:

Approving Auth Signature Date

Recommendations

Change Order Number

Change Control Board (CCB)

• Also called Configuration Control Board

• A group of people responsible for evaluating and approving and disapproving proposed changes to configuration items, and for implementation of approved changes.

• Typical CCB members

- Project Manager

- User Representative

- Quality Controller

- Configuration Controller

Some Good Practices

• Keep version history in the configuration item.

• Item to contain exact item name, version number, date

• Identify configuration items to be tracked

• Code should have history in the comment

• Highlight the changes in the document atleast for two versions.

Configuration Audit

Configuration Audits

• To ensure that what has been built is in conformance with what was required (original specifications and change requests) by analysing :

- Test reports

- review reports

- change logs

Definition

Verification of a configuration item’s compliance with its configuration identification

Status Accounting

An ounce of derivation is worth a pound of analysis

- Wayne Babich

Configuration Status Accounting & Reporting

• Keep track of

- Current identification of items

- Configuration of delivered software

- Status of change requests / problem reports

- Status of approved changes

IEEE Definition

An element of configuration management, consisting of the recording and reporting of information needed to manage a configuration effectively

Typical Information

Baseline Library

Items / Units

Baseline Units

Release

Release Units

Change OrderBackup

Backup Units

Check-in / Check-out

Change Request/ Problem Log

Standard Reports

• Summary list Change Requests / Problem Reports

• List of CR / PR pending approval

• Summary list of Change Orders

• List of Change Orders pending completion

• Items and versions of a Baseline

• Current set of units in the library

• List of changes since Baseline

• List of checked-out items

• History of backups

• History of releases

• List of items / versions in a baseline

• List of items / version in a release

Typical Uses of the Configuration Accounting Data

• In which backup is version 1.6 of P13?

• What are the program level changes between release 5.1 and 5.2?

• Which programs were replaced in release 5.2?

• Which items were changed for Change Order 671? What were the versions of the units before and after the change? Have all the changes been incorporated and checked-in?

Can we make SCM happen?

Thank You