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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
.
- Note:
- 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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