The Windows operating system has experienced the change from 16 to 32-bit, on the 16-bit platform, Windows3.x, in addition to the support of OLE, although the operating system has established according to the structure of the component (DLL) module, but modules and modules Most of the COM interfaces are not used, so the advantages of this component model have not been fully utilized; in the 32-bit Windows version, no matter whether Windows95 / 98 is still NT, many system components are implemented in the form of COM, except for consideration In addition to the version of SDK compatibility, some new components provide COM interfaces, which do not only make various development languages can directly call the functionality provided by the system, but also help to upgrade the components in special circumstances. And this part of this upgrade is very difficult for MS-DOS systems and 16-bit Windows systems.
On the Windows operating system platform, there are some component models that use COM to greatly enrich Windows functionality, and the Windows feature extension is also more flexible. E.g
1 DirectX multimedia package. It provides powerful multimedia functions for the Windows platform in the form of COM interface, which is now widely used in the development of game entertainment software and other multimedia software.
2 RDO (Remote Data Object, Remote Data Object) and DAO (Data Access Object, Data Access Object) Database Access Object Library. It provides a convenient way to operate in the form of COM automation objects. The data access consistent interface OLE DB / ADO (Active Data Object, Active Data Object) is more drizzle to play the role of the COM interface.
3 Internet Client SDK. It provides a set of COM libraries that add Internet features for the application system to provide the underlying transparency.
Others have some components such as MAPI (Message API, Messaging interface), ADSI (Active Directory Service Interface, Active Directory Service Interface), etc., all provide a consistent, efficient service. From the entire Windows operating system, COM has become the basic software model of the system, which brings flexibility and high efficiency, as well as application development consistency.
From Pan Aimin "COM Principles and Applications".
