HP WBEM Services Software Developer's Kit for HP-UX Provider and Client Developer's Guide A.01
Schema Design and Implementation
Schema Design
Chapter 3 33
• Statistics are statistical information relevant to a given managed
element. An example use is representing resource utilization of a
running process.
• Diagnostics are diagnostic invocation, settings, and results. An
example use is disk diagnostics.
•AnIndication is the representation of the occurrence of an event.
An example use is disk errors.
• Services for Provider Control are schema that allow control by a
client of a provider's internal operations.
The process of identifying appropriate objects and their relationships is
referred to as Object Oriented Design and Analysis (OOD/OOA). While a
full discussion of OOD/OOA is out of the scope of this document and a
comprehensive understanding is not required for effective CIM
modeling, a general understanding of the concepts of object modeling is
helpful. A good overview of the most useful concepts can be found in the
DMTF CIM Tutorial, posted at http://www.dmtf.org/education/ ,
which has a more theoretical approach to Schema Design and
Implementation. Still, the most important prerequisite for effective
modeling is expertise in the domain being modeled.
Creating a draft model of a specific domain is usually best begun by
sketching diagrams using the Unified Modeling Language™ (UML™).
UML provides a simple visualization of object classes and their
relationships. Thinking of objects as being of the types listed above can
be helpful. It is best to identify the managed elements first. These are
the primary entities that are to be managed.
Next, determine the associations and aggregations that relate these
entities. All associations and aggregations have at least two (2)
properties, the references to the classes being associated. These
relationships have a cardinality or minimum/maximum count on the
number of objects that can relate to another object. Cardinality is
represented in UML by placing the ranges next to the classes at the ends
of the association or aggregation (for example "1..
n
" indicates there can
be 1 to "
n
" instances of the object tied by that relationship to another
object). If the cardinality is labelled “*” or if no cardinality is explicitly
specified, it is assumed to be "0..
n
".