WMI - Windows Management Instrumentation
WMI is the Microsoft implementation of the Common Information Model (CIM) initiative developed by the Distributed Management Task Force (DMTF). The DMTF is an association of various computer and software companies (e.g. Novell, Microsoft, Cisco, HP, etc.) developing standards in the Enterprise management space. (See http://www.dmtf.org for more information.) As large Enterprises have many computers with many software environments, managing these diverse environments can be a real challenge. In order to unify the management techniques for the sake of simplicity, the DMTF defined CIM to represent real-world manageable entities in a unified way. The CIM object model is an object data model using terms and semantic that is unique to all constructors and software developers. This object model is implemented in a database called the CIM repository.Based on the CIM model, WMI includes real-world manageable components, available from the DMTF standards with some specific extensions that represent the various Windows components. Moreover, WMI exposes a collection of COM scriptable objects that allow various applications to take advantage of the management information. WMI is the Microsoft implementation of CIM.
As part of the installation process, most of the Microsoft applications available today (e.g. SQL 2000, Exchange 2000/2003, Office 2000/XP/2003, Internet Explorer 6.0, Host Integration Server, Automated Deployment Services) extend the standard CIM object model to add the representation of their manageable entities in the CIM repository. This representation is called a class, and it exposes information through properties and allows the execution of some actions via methods. The access to the manageable entities is made via a software component, called a “provider” which is nothing else than a DLL implementing a COM object written in C/C++ (See note at the end of this section). Because a provider is designed to access some specific management information, the CIM repository is also logically divided into several areas called namespaces. Each namespace contains a set of providers with their related classes specific to a management area (i.e. RootDirectorydap for active directory, rootsnmp for snmp information or rootmicrosoftiisv2 for internet information server information).
To locate the huge amount of management information available from the CIM repository, WMI comes with a sql-like language called the WMI Query Language (WQL).
posted by Hervé SCHLECHT @ 9:18 PM
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