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MOM WMI Classes

MOM WMI Classes

System Center

Overview of WMI

Windows Management Instrumentation (WMI) is an object-oriented technology for programs to store information in a central repository. Other programs or scripts can access the information in this repository and call class methods to interact with the program and control its operation. WMI makes automating management tasks easier, and it allows administrators to securely manage computers and services remotely.

Note Note   

The MOM WMI classes has been deprecated and should not be used when creating new scripts. The WMI classes are included only to support existing scripts.

Namespaces and Other Naming Conventions

All MOM WMI classes exist in the root\MOM WMI namespace. MOM classes in that namespace use the MSFT_ prefix.

WMI Access and Security

Members of the local Administrators group have full permissions in the MOM WMI namespace, while members of the Everyone group have the following permissions:

  • Execute Methods
  • Provider Write
  • Enable Account

When connecting to WMI from a remote computer, the Everyone account must have Remote Enable permission for the root\MOM namespace.

Users must also be members of either the MOM Administrators or MOM Users group to access the MOM WMI objects. To modify properties or execute methods, members must belong to the MOM Administrators group.

To increase system security, the preconfigured MOM user groups do not have permission for the MOM WMI namespace. To access the MOM WMI classes from a remote computer using an account in a MOM user group, you must add the user group and explicitly grant the Remote Enable permission to the user group.

To modify the default settings for the root\MOM namespace, open the Computer Management MMC console, right-click WMI Control, and then select Properties. WMI security settings are modified on the Security tab.

MOM and WMI

MOM exposes internal information about events, alerts, and computers through its WMI providers. Other programs with appropriate permissions can read and, in some cases, modify the data. The MOM WMI objects are stored on the server running MOM. They are not stored on agent computers. WMI objects on the server running MOM can be accessed remotely from other computers.

The root\MOM namespace includes the following WMI classes:

The following illustration shows the MOM WMI classes and the associations between them.

 MOM WMI Classes

When to Use the WMI Classes

Some of the information available from the MOM WMI classes is also available by directly querying the MOM SQL views. In cases where query speed is the most important requirement for your program, the SQL views provide better performance.

If greater ease of use or the ability to modify data is required, the MOM WMI classes are more likely to meet your needs. WMI requires no special knowledge about the MOM SQL Server database format, and the WMI APIs include a COM interface that is easily called from scripts running under the Windows Script Host. The Windows Script Host supports JScript, VBScript, and several third-party ActiveX scripting languages, including Perl.

The MOM Operations Database can store a large amount of data about alerts and other items. You can improve the performance and reliability of WMI by sending queries that are as specific as possible. This is more efficient than querying all the objects of a given class, and then relying on the logic within the script to filter the results.

For more information about WMI concepts and the built-in Windows APIs used to query the WMI repository, see WMI SDK.

For more information about the Windows Script Host and the VBScript and JScript languages, see Windows Script.

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