COM CALL-OUT FOR OFFICE AUTOMATION (Word & Excel)


	In COM, applications interact with each other and with the system through collections of functions called interfaces. Note that all OLE services are simply COM interfaces. A COM interface is a strongly-typed contract between software components to provide a small but useful set of semantically related operations (methods). An interface is the definition of an expected behavior and expected responsibilities
	An application instantiates a component and calls one of its method. COM method calls are merely C++ virtual function calls.
	A virtual function table is an array of pointers to the methods an object supports.
	In C an object would appear as a structure whose first member is a pointer to the virtual function table that is, the first member points to an array containing function pointers
	The function pointer than calls the function(which is a method for the component).
	So calling a component method is actually calling a pointer to a function pointer which calls the function.