28 IBM TotalStorage Productivity Center: The Next Generation
2.3 Common Information Model
The CIM Agent provides a means by which a device can be managed by common building
blocks rather than proprietary software. If a device is CIM-compliant, software that is also
CIM-compliant can manage the device. Vendor applications can benefit from adopting the
common information model because they can manage CIM-compliant devices in a common
way, rather than using device-specific programming interfaces. Using CIM, you can perform
tasks in a consistent manner across devices and vendors.
CIM uses schemas as a kind of class library to define objects and methods. The schemas
can be categorized into three types:
Core schema define classes and relationships of objects.
Common schema define common components of systems.
Extension schema are the entry point for vendors to implement their own schema.
The CIM/WBEM architecture defines the following elements:
Agent code or CIM Agent
An open-systems standard that interprets CIM requests and responses as they transfer
between the client application and the device. The Agent is embedded into a device, which
can be hardware or software.
CIM Object Manager
The common conceptual framework for data management that receives, validates, and
authenticates the CIM requests from the client application. It then directs the requests to
the appropriate component or a device provider such as a CIM Agent.
Client application or CIM Client
A storage management program, such as TotalStorage Productivity Center, that initiates
CIM requests to the CIM Agent for the device. A CIM Client can reside anywhere in the
network, because it uses HTTP to talk to CIM Object Managers and Agents.
Device or CIM Managed Object
A Managed Object is a hardware or software component that can be managed by a
management application by using CIM, for example, a IBM SAN Volume Controller.
Device provider
A device-specific handler that serves as a plug-in for the CIMOM. That is, the CIMOM
uses the handler to interface with the device.
Integrating existing devices into the CIM model
Because these standards are still evolving, we cannot expect that all devices will support the
native CIM interface. As a result, the SMI-S is introducing CIM Agents and CIM Object
Managers. The agents and object managers bridge proprietary device management to device
management models and protocols used by SMI-S. The agent is used for one device and an
object manager for a set of devices. This type of operation is also called
proxy model and is
shown in Figure 2-8 on page 29.
Note: The terms CIM Agent and CIMOM are often used interchangeably. At this time, few
devices come with an integrated CIM Agent. Most devices need a external CIMOM for CIM
to enable management applications (CIM Clients) to talk to the device.
For ease of installation, IBM provides an Integrated Configuration Agent Technology
(ICAT), which is a bundle that includes the CIMOM, the device provider, and an SLP SA.