The Devices Model is a representation of the discrete logical units on the system that provide the basic capabilities of the system, such as storage, processing, communication, and input/output functions. There is a strong temptation to identify the system devices with the physical components of the system. This approach is incorrect because what is being managed is not the physical components themselves but rather the operating system's representation of the devices.
The representation provided by the operating system does not have a one-to-one correspondence with the physical components of the system. For example, a modem may correspond to a discrete physical component. It may just as well be provided by a multi-function card that supports a LAN adapter as well as a modem, or the modem may be provided by an ordinary process running on the system. It is very important in using or making extensions to the model to understand this distinction between Logical Devices and Physical Components and not to get them confused.
The CIM Application Management Model is an information model designed to describe a set of details that is commonly required to manage software products and applications. This model can be used for various application structures, ranging from stand-alone desktop applications to a sophisticated, multiplatform, distributed, Internet-based application. Likewise, the model can be used to describe a single software product as well as a group of interdependent applications that form a business system.
A fundamental characteristic of the application model is the idea of the application life cycle. An application may be in one of four states: Deployable, Installable, Executable, and Executing. The interpretation and characteristics of the various objects used to represent applications are largely tied to the mechanisms used to transform applications from one state to another.
The Networks Model represents the various aspects of the network environment. This includes the topology of the network, the connectivity of the network, and the various protocols and services necessary to drive and provide access to the network.
The Physical Model provides a representation of the actual physical environment. Most of the managed environment is represented by logical objects, that is, objects that represent informational aspects of the environment rather than actual physical objects. Most of systems management is concerned with manipulating information that represents and controls the state of the system. Any impact on the actual physical environment (such as the movement of a read head on a physical drive, or the starting of a fan) is likely to only happen as an indirect consequence of the manipulation of the logical environment. As such, the physical environment is typically not of direct concern.
Apart from anything else, physical parts of the system are not instrumented. Their current state (and possibly even their very existence) can only be indirectly inferred from other information about the system. In the CIM, the physical model is a representation of this aspect of the environment and it is expected that it will differ dramatically from system to system and over time as technology evolves. It is also expected that the physical environment will always be very difficult to track and instrument, spawning the opportunity for a separate specialty, that of deploying applications, tools, and environments specifically aimed at providing information about the physical aspect of the managed environment.