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 45
Performance considerations in case (3) usually involve situations where
a large number of instances are retrieved (and perhaps filtered) to obtain
the necessary information.
An example of this case would be an application which wishes to show
the total disk space available on a platform. Retrieving all disk instances
and adding up the disk space available on each would be fine for a small
number of disks, but as the number of disks grows to the hundreds or
even thousands, performance of sending large XML messages across the
network may become a concern. An alternative would be to use another
class to represent the total disk space (such as a subclass of
CIM_PhysicalCapacity) which when queried would have the provider
(instead of the client) add up the total space before sending a smaller
message with the data required to the client application.
A second example would be a client looking for instances of
CIM_SoftwareElement which correspond to device drivers. In this case
enumerating all instances of CIM_SoftwareElement and then filtering
those of interest could be very inefficient. Instead, creating a separate
subclass of CIM_SoftwareElement for the device drivers would allow the
client to enumerate just those instances of interest.