Microsoft OLE DB 2.0 Programmers Reference and Data Access SDK (Microsoft Professional Editions)

OLE DB defines registry entries for providers, enumerators, and error lookup services. These entries contain the class ID of the component and its associated DLL, description, display name, and so on. Following are several reasons for registering these OLE DB components:

• Registration is required as part of being a COM component and provides a way to create an instance of a COM object.
• Registration provides the mechanism for the Data Links user-interface component and the root enumerator shipped with the OLE DB component of the Microsoft Data Access Components (MDAC) SDK to obtain a list of providers on the machine.
• Registration provides the mechanism for the root enumerator to obtain a list of other enumerators. An enumerator is a COM server that implements ISourcesRowset.
• Registration provides the mechanism for the standard OLE DB error object to invoke the provider's custom error lookup service.
• Data may be available in different formats. Registration provides a way to obtain a list of data formats and the providers that support those data formats. Data formats are created by providers and can be provider-specific. A provider might consider itself capable of supporting many data formats. A usage example would be to group providers together and help consumers interactively decide which provider might work for them.

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