6.1 Physical or Electronic Objects

Source code is far from the only type of objects that might be placed under configuration management, though this is traditionally the most common type. If you look at a product's entire life cycle, objects may belong to the product itself or may support its development and maintenance.

Configuration Item Class Hierarchy

No matter how and where objects are produced, they fall into distinct classes: physical and electronic. These are illustrated in Figure 6-1, which shows an extract of the class hierarchy that can be drawn for configuration items. The last row shows instantiation of the configuration item classes just above. Some differences between the two classes need to be understood in terms of configuration management.

Figure 6-1. Configuration Item Class Hierarchy

Physical Objects

The characteristics of a physical object in configuration management perspective are

• It exists in a limited number of copiessometimes only one.

• When a copy of the object is delivered, the number of available copies is reduced.

• It cannot be stored on a computer but must be stored in a physical place.

• Writing metadata on the object may or may not be possible.

• Most traditional configuration management tools cannot handle a physical object without a proxy-object in electronic form.

• Only the most advanced stock handling systems are able to extract a physical object from storage based on the metadata.

A few examples of physical objects are

• The paper napkin on which the original idea was sketched

• Workstations to be delivered as parts of the system

• Workstations used for development

• Cables

• The box that the hardware parts with the embedded software are to be placed in

• Boards

Electronic Objects

The characteristics of an electronic object in configuration management perspective are

• An unlimited number of copies may be easily produced.

• Delivery of a copy does not reduce the available number of copies.

• Copies may be produced/extracted/delivered without anybody noticing.

• Copies may be in either electronic or physical form.

• It must be stored electronically .

• Metadata for the object may be contained in the object itself and/or in the computer (as part of the operating system and/or a tool).

• Metadata can be a direct pointer to the object and can be used to extract the object from storage.

A few examples of electronic objects are the user requirement document written in Word, a software module written in C, a database system (middleware), and an operating system.