Software Configuration Management (SCM)

Configuration management(CM)is the discipline of controlling the evolution of complex systems; software configuration management (SCM) is its specialization for computer programs and associated documents. SCM differs from general CM in the following two ways. First, software is easier to change than hardware, and it therefore changes faster. Even relatively small software systems, developed by a single team, can experience a significant rate of change, and in large systems, such as telecommunications systems, the update activities can totally overwhelm manual configuration management procedures. Second, SCM is potentially more automatable
because all components of a software system are easily stored on-line.

The goals of SCM are :
* Configuration identification - Identifying configurations, configuration items and baselines.
* Configuration control - Implementing a controlled change process. This is usually achieved by setting up a change control board whose primary function is to approve or reject all change requests that are sent against any baseline.
* Configuration status accounting - Recording and reporting all the necessary information on the status of the development process.
* Configuration auditing - Ensuring that configurations contain all their intended parts and are sound with respect to their specifying documents, including requirements, architectural specifications and user manuals.
* Build management - Managing the process and tools used for builds.
* Process management - Ensuring adherence to the organization's development process.
* Environment management - Managing the software and hardware that host our system.
* Teamwork - Facilitate team interactions related to the process.
* Defect tracking - Making sure every defect has traceability back to the source.

Basic SCM Concepts :
defines the basic elements of a data base for software configuration management. The data base stores all software objects produced during the life-cycle of a project.
- Creation of Software Objects : A source object is a software object that is composed manually, for instance with an interactive editor. Creating a source object requires human action; it cannot be produced automatically.A derived object is generated fully automatically by a program, usually from other software objects. A program that produces derived objects is called a deriver. Examples of derivers are compilers, linkers, document formatters, pretty printers, cross referencers, and call graph generators.
- Structure of Software Objects : The body of a software object is either atomic or structured. An atomic object, or atom, has a body that is not decomposable for SCM; its body is an opaque data structure with a set of generic operations such as copying, deletion, renaming, and editing. A configuration has a body that consists of sub-objects, which may themselves have sub-objects, and so on. Configurations have two subclasses: composites and sequences. A composite object, or simply composite, is a record structure comprised of fields. Each field consists of a field identifier and s field value. A field value is either an object identifier or a version group identifier. A sequence is a list of object and version group identifiers. Sequences represent ordered multi-sets of objects.