configuration management

Configuration Management

Configuration management

Configuration management is unique identification, controlled storage, change
control, and status reporting of selected intermediate work products, product
components, and products during the life of a system.

Configuration Management Planning

Configuration Management starts during the early phases of the project All products of the software process may have to be managed

Example:
o    Specifications
o    code
o    Designs
o    Programs
o    Test data
o    User manuals
 
Thousands of separate documents may be generated for a large software system

Configuration Management Plan

o    Defines the types of documents to be managed and a document naming scheme
o    Defines who takes responsibility for the CM procedures and creation of “baselines”
o    Defines policies for change control and version management
o    Defines the CM records which must be maintained
o    Describes the tools which should be used to assist the CM process and any limitations on their use

Configuration item identification
 
o    Large projects typically produce thousands of documents which must be uniquely identified. Some of these documents must be maintained for the lifetime of the software
o    Document naming scheme should be defined so that related documents have related names.
o    A hierarchical scheme with multi-level names is probably the most flexible approach

The configuration database
 
All CM information should be maintained in a configuration database. This should allow queries about configurations to be answered
o    Who has a particular system version?
o    What platform is required for a particular version?
o    What versions are affected by a change to component X?
o    How many reported faults in version T?
o    The CM database should preferably be linked to the software being managed

Change Management

Software systems are subject to continual change requests
o    From users
o    From developers
o    From market forces

Change management is concerned with keeping track of these changes and ensuring that they are implemented in the most cost-effective way

Version and Release Management

o    Invent identification scheme for system versions
o    Plan when new system version is to be produced
o    Ensure that version management procedures and tools are properly applied
o    Plan and distribute new system releases

Versions/Variants/Releases

Version: An instance of a system which is functionally distinct in some way from other system instances

Variant:  An instance of a system which is functionally identical but non-functionally distinct from other instances of a system

Release:  An instance of a system which is distributed to users outside of the development team

Version identification

o    Procedures for version identification should define an unambiguous way of identifying component versions
o    Three basic techniques for component identification
o    Version numbering
o    Attribute-based identification
o    Change-oriented identification

Release management

o    Releases incorporate changes forced on the system by errors discovered by users and by hardware changes
o    They also incorporate new system functionality
o    Release planning is concerned with when to issue a system version as a release

System releases

o    Not just a set of executable programs, may also include Compilers
o    configuration files defining how the release is configured for a particular installation
o    Data files needed for system operation
o    An installation program or shell script to install the system on target hardware
o    Electronic and paper documentation
o    Packaging and associated publicity
o    Systems are now normally released on CD-ROM or as downloadable installation files from the Web

Release problems

o    Customer may not want a new release of the system
o    They may be happy with their current system as the new version may provide unwanted functionality 
o    Release management must not assume that all previous releases have been accepted
o    All files required for a release should be re-created when a new release is installed

Release creation
o    Release creation involves collecting all files and documentation required to create a system release
o    Configuration descriptions have to be written for different hardware and installation scripts have to be written
o    The specific release must be documented to record exactly what files were used to create it
•    This allows it to be re-created if necessary

System building

o    The process of compiling and linking software components into an executable system
o    Different systems are built from different
combinations of components
o    Invariably supported by automated tools that are driven by ‘build scripts’

System building problems

o    When there are many hundreds of components making up a system, it is easy to miss one out; this should normally be detected by the linker.
o    A system built with the wrong version may work initially but fail after delivery
o    Embedding absolute names in code almost always causes problems as naming conventions differ from place to place
o    Different compiler versions may actually generate different code and the compiled component will exhibit different behaviour

Key points

o    Configuration management is the management of system change to software products
o    A formal document naming scheme should be established and documents should be managed in a database
o    The configuration database should record information about changes and change requests
o    A consistent scheme of version identification should be established using version numbers, attributes or change sets
o    System releases include executable code, data, configuration files and documentation
o    System building involves assembling components into a system 
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Configuration Management FAQ