Understanding Windows Management Instrumentation

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Windows Management Instrumentation (WMI) is Microsoft’s implementation of Web-Based Enterprise Management (WBEM), an industry initiative adopted by the Distributed Management Task Force (DMTF) to implement a common interface between management applications, such as SMS, and management entities, such as SMS objects. SMS objects include discovery data, client computers, packages, advertisements, sites, and site control information. This common interface is called the Common Information Model (CIM) repository. It defines a standard schema for storing and exposing object data. Providers are components that collect object information from managed objects and store them in the CIM repository. A management application can then obtain that information from the CIM repository and make it available for view and analysis.

This interface feature is similar to installing a Windows device driver such as a printer driver. The print device manufacturer provides a printer driver that’s compatible with Windows. All Windows applications use this same printer driver to generate print jobs on the print device. Using a similar premise, with WMI installed, any management application program can collect and set configuration details for a wide variety of hardware types, operating system components, and application systems because it uses providers to work with those systems. Providers can be written to store and expose data in the CIM repository, and management applications (written with Microsoft Visual Basic, SQL Server, Java, Open Database Connectivity (ODBC), Active Directory Service Interface (ADSI), and so on) can be created to obtain that data from the CIM repository.

To illustrate, a hardware provider on the SMS client stores SMS object information such as hardware inventory in the CIM repository. SMS agents such as the Hardware Inventory Client Agent extract that data from the CIM repository and report it to the SMS database. The SMS Provider, which can be installed on the SMS site server or the SQL Server, accesses the SMS database to provide the data to the SMS Administrator Console. Figure 1.3 demonstrates this relationship.

Figure 1.3: Relationship between the SMS Provider, the WMI, and the SMS database.

The SMS site database objects, views, and tables aren’t directly accessible or modifiable except through the WMI layer. SMS provides an open architecture, however, that makes it possible to create tools other than the SMS Administrator Console that can access and manipulate the SMS database objects. In essence, you could use any WMI-compliant and ODBC-compliant application to access these objects. So you could view the data with a Web browser using ActiveX controls or Java, through applications written using C++, Visual Basic, or the Component Object Model (COM).

WMI is installed with Windows 2000, Windows XP, and the Windows Server 2003 family operating systems. It’s also installed on all Windows 98 and Windows NT 4.0 clients when the SMS client is installed. The registry is modified to reflect the WMI component installation, and the Windows Management Instrumentation service is installed and started. Of course, it’s already available on Windows 2000 and later clients. If WMI has already been installed on the desktop, SMS requires that it be WMI version 1.50.1085 or later.

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