HP WBEM Services Software Developer's Kit for HP-UX Provider and Client Developer's Guide A.01

Schema Design and Implementation
Schema Implementation
Chapter 3 47
• Instance Definitions
Instances can be defined in MOF. The result of these definitions is
that a provider supporting instances of the class receives a request to
create an instance with the values specified in the MOF file.
Registering Providers
The CIM Server associates classes with the providers that instrument
them through instances of the Provider Registration classes in the
special root/PG_InterOp namespace: PG_Provider,
PG_ProviderModule, and PG_ProviderCapabilities. An example is
shown in the section on Provider Registration and Naming. While
provider registration instances are conveniently specified in MOF, they
should be in a different file than the one used to specify the schema
definition so that these different components can be managed separately.
Note that the provider registration mechanism of HP WBEM Services for
HP-UX eliminates difficulties encountered with the Provider qualifier.
These include:
• Requires modification of schema definition (which is in principle
improper if the schema being modified is part of the DMTF-supplied
CIM schema)
• Does not distinguish between an Instance and an Association
provider for an association class
• Does not permit more than one provider to a class
• Cannot specify supported properties or methods
HP WBEM Services for HP-UX ignores the Provider qualifier if present.
Rules for Updating Schema
There are several considerations when either planning or implementing
an upgrade to a previously released MOF file.
Backward Compatibility
It is very important to consider backward compatibility when upgrading
a MOF file because CIM clients may continue operation before and after
a MOF/provider upgrade. Causes of failures in applications due to
upgrades include (but are not limited to):