Posted: Apr. 14, 2003

Windows Management Instrumentation (WMI) allows management applications, such as a script, to get or set information about a computer’s resources. Computer resources include the Windows OS services, utilities, performance counters, event logs, physical (such as the disk drive) and logical (such as the disk volume) hardware, and applications.

The key architectural components of WMI (enclosed in the dashed box) are WMI providers, the Common Information Model (CIM) Object Manager (CIMOM), and the CIM repository.

WMI providers (bottom). Similar to hardware device drivers, providers communicate with and monitor physical and logical computer components, such as Windows OS services and utilities, hardware (such as hard drives), network interface cards, and applications.

CIMOM. The CIMOM manages communication between WMI providers, the CIM repository, and management applications by registering which providers are available and the capabilities they expose, routing information requests to the appropriate provider, processing queries for information written in a SQL-like WMI Query Language (WQL), validating security, and providing the necessary infrastructure for event monitoring.

CIM repository. The CIM repository is a central storage area used by the CIMOM to store registration information about WMI providers and applications and to cache some management data. However, in most cases the CIMOM derives dynamically changing data (such as free disk space) by querying WMI providers, rather than storing the data in the CIM repository where it would soon be out of date.

WMI also provides a WMI Scripting Library, which is a set of COM objects that allow scripts to interface with the WMI infrastructure, enumerate the management information, and handle other issues such as security.

Management applications are the major consumers of WMI information. These applications can be as simple as a script that an administrator writes to solve a specific management problem, such as checking for the amount of free space on a hard drive, or as complex as Microsoft's management products, Systems Management Server (SMS) and Microsoft Operations Manager (MOM). Management applications can read and report management information, and in many cases actually set management parameters, such as the amount of disk space (quota) that a user can access.