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.
Chapter 2. Key concepts 29
The CIM Agent or CIMOM translates a proprietary management interface to the CIM
interface. The CIM Agent for the IBM TotalStorage ESS includes a CIMOM inside it.
In the future, more and more devices will be native CIM compliant, and will therefore have a
built-in Agent as shown in the Embedded Model in Figure 2-8. When widely adopted, SMI-S
will streamline the way that the entire storage industry deals with management. Management
application developers will no longer be required to integrate incompatible feature-poor
interfaces into their products. Component developers will no longer be required to push their
unique interface functionality to application developers. Instead, both will be better able to
concentrate on developing features and functions that have value to end-users. Ultimately,
faced with reduced costs for management, end-users will be able to adopt
storage-networking technology faster and build larger, more powerful networks.
Figure 2-8 CIM Agent and Object Manager overview
CIM Agent implementation
When a CIM Agent implementation is available for a supported device, the device can be
accessed and configured by management applications using industry-standard
XML-over-HTTP transactions. This interface enables IBM TotalStorage Productivity Center
for Data, IBM TotalStorage Productivity Center for Disk, IBM TotalStorage Productivity Center
for Replication, IBM Director and vendor tools to manage the SAN infrastructure more
effectively.
By implementing a standard interface over all devices, an open environment is created in
which tools from a variety of vendors can work together. This reduces the cost of developing
integrated management applications, installing and configuring management applications,
and managing the SAN infrastructure. Figure 2-9 on page 30 shows an overview of the CIM
Agent.
0..n
Agent
Device or
Subsystem
Device or
Subsystem
1
1
n
Proprietary
Proprietary
Proxy Model Proxy Model
Embedded Model
0..n
Agent
Device or
Subsystem
1
0..n
Provider
Object Manager
CIMxml
CIM operations over http [TCP/IP]
0..n
CIM Client
Management
Application

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