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Systems Management: Common Information Model (CIM)
Copyright © 1998 The Open Group

Managed Object Format

The management information is described in a language based on the Interface Definition Language (IDL) - see the DCE RPC Specification (C309, listed in Referenced Documents) called the Managed Object Format (MOF).

This specification uses the term MOF specification to refer to a collection of management information described in a manner conformant to the MOF syntax.

Elements of MOF syntax are introduced on a case-by-case basis, with examples. In addition, a complete description of the MOF syntax is provided in MOF Syntax Grammar Description .

All grammars defined in this specification use the notation defined in the UNICODE Standard, Version 2.0 (see Referenced Documents). Any exceptions are stated with the grammar.

The MOF syntax is a way to describe object definitions in textual form. It establishes the syntax for writing definitions. The main components of a MOF specification are textual descriptions of classes, associations, properties, references, methods and instance declarations and their associated qualifiers. Comments are permitted.

In addition to serving the need for specifying the managed objects, a MOF specification can be processed using a compiler. To assist the process of compilation, a MOF specification consists of a series of compiler directives.

A MOF file can be encoded in either Unicode or UTF-8.

MOF Usage

The managed object descriptions in a MOF specification can be validated against an active namespace (see Naming ). Such validation is typically implemented in an entity acting in the role of a Server. This section describes the behavior of an implementation when introducing a MOF specification into a namespace. Typically, such a process validates both the syntactic correctness of a MOF specification, as well as the semantic correctness of such a specification against a particular implementation. A MOF specification can be validated for the syntactic correctness alone, in a component such as a MOF compiler.

Class Declarations

A class declaration is treated as an instruction to create a new class. It is a local matter as to whether the process of introducing a MOF specification into a namespace is allowed to change classes or modify classes.

Any class referenced in the specification of a class or reference specification must exist at the time of the specification (that is, forward references are not allowed).

Instance Declarations

Classes must be defined before they are used to declare instances. However, if a class definition is already resident within the namespace, then that class declaration need not appear in a MOF specification that introduces the instances of that class.

Any instance declaration is treated as an instruction to create a new instance where the object's key values do not already exist, or an instruction to modify an existing instance where an object with identical key values already exists.

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