The OLE libraries, OLECLI.DLL and OLESVR.DLL, use DDE messages to communicate with each other. Although client and server applications can use DDE directly, without employing OLECLI.DLL or OLESVR.DLL, this method of implementing OLE is not recommended. Future enhancements to the OLE libraries will benefit applications that use the libraries but will not benefit applications that use DDE directly.
The following information about the DDE-based OLE protocol is provided for applications that must implement DDE directly, despite losing the ability to take advantage of future enhancements to the system.
Implementation of the OLE protocol requires implementation of the underlying DDE protocol. All the standard DDE rules and facilities apply. Applications that conform to this protocol must also conform to the DDE specification. Conforming to this specification implies supporting the System topic and the standard items in that topic.