Note OLE is implemented mainly through the use of two DLLs, OLESVR.DLL and OLECLI.DLL. A third DLL, named SHELL.DLL, is used to register OLE server applications, and to maintain and query the registration database. For information on implementing this DLL, see Chapter 10, "Using the Registration Database."
OLECLI.DLL contains functions that are called by the client applications. These functions do tasks such as managing conversations between client and server applications, rendering objects for the client, and launching server applications to manipulate linked and embedded objects.
Figure 38 shows that the client application calls functions within OLECLI.DLL during OLE operations—such as when a user double-clicks on an object previously inserted in the client application's document.
Figure 38. Relationship between applications and OLE DLLs
Note As shown in Figure 38, communication between the OLESVR.DLL and OLECLI.DLL is handled via DDE. Future versions of OLE may not use DDE for its communication protocol; this will not affect your implementation of OLE because DDE is transparent to client and server applications.