how many class is here in only one COM?

every one. We know that COM server exsits as dll or ax. We can use COM component through calling CoCreateInstance. you known that each COM class has a 开发者_如何学运维CLSID. we use CLSID to create a object. I want to answer that how many COM classes can implement in one dll(COM server).

A single .dll file (in-proc COM server) can serve any sane number of COM classes - we have a commercial product that is shipped with a single COM server implementing something like twenty COM classes.

The fact that Windows registry will map multiple class ids onto the same .dll file isn't a problem - there's DllGetClassObject() function in every in-proc COM server that is passed the class id requested and retrieves the right class factory. So a single in-proc COM server cam serve multiple COM classes.