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

Client Implementation

Navigating Schema

Chapter 5 95

subclasses of CIM_LogicalDevice) might have common values for

DeviceID, having values for CreationClassName which match their

individual class names ensures uniqueness.

Enumerating Instance Names

When a client performs the enumerateInstanceNames CIM operation, it

speciﬁes a namespace and a class name. The CIM server then returns

values of the key properties for instances of that class within the

speciﬁed namespace. Each instance is uniquely deﬁned by the values of

its key properties. The enumerateInstanceNames operation returns all

instances of the class speciﬁed, which include instances of all of its

subclasses, since those are also instances of the speciﬁed class. For

example, enumerating instance names of CIM_LogicalPort would

return any instances of its subclasses, CIM_USBPort and CIM_FibrePort,

as well as possible instances of CIM_LogicalPort, if any, that are not

instances of those subclasses.

The enumerateInstances operation works in a similar manner though

it also returns the other properties of the class and subclasses. Thus in

the example above, in addition to the set of keys deﬁned for

CIM_LogicalPort, the enumerateInstances operation would return all

properties on the instances returned. In particular, it would also return

any additional properties of CIM_USBPort and CIM_FibrePort that may

be unique to these subclasses.

Propagated Keys

There are two techniques for associating instances of classes with one

another: using propagated keys, which deﬁne weak associations

(described here), and using association classes (discussed below). Each

technique has its own particular advantages. Understanding those

advantages enables the client application to more efﬁciently access

information and functionality within the schema.

Scoping

Propagated keys deﬁne a context or scope within which instances of a

particular class are unique. Examples of scoping relationships include:

• Logical Device on a Computer System

• User Account within a Domain

• Operating System running on a Computer System