客戶調用COM流程，調用com流程

客戶調用COM流程，調用com流程

參考：COM技術內幕

DllGetClassObject
https://msdn.microsoft.com/en-us/library/windows/desktop/ms680760.aspx  
If a call to the CoGetClassObject function finds the class object that is to be loaded in a DLL,
CoGetClassObject uses the DLL's exported DllGetClassObject function.

IClassFactory
https://msdn.microsoft.com/en-us/library/windows/desktop/ms694364.aspx
After calling the CoGetClassObject function to get an IClassFactory interface pointer to the class object,
call the CreateInstance method of this interface to create an object.

CoCreateInstance
https://msdn.microsoft.com/en-us/library/windows/desktop/ms686615.aspx
CoCreateInstance等價
{
    CoGetClassObject(rclsid, dwClsContext, NULL, IID_IClassFactory, &pCF);
    hresult = pCF->CreateInstance(pUnkOuter, riid, ppvObj
    pCF->Release();
}

CoGetClassObject: 將在注冊表中查找指定的組件。找到之後，它將裝載實現此組件的DLL。
    裝載成功之後，它將調用在DLL服務器中實現的DllGetClassObject。
DllGetClassObject: 此函數的作用是創建響應的類場。
    查詢IClassFactory接口，並將其返回給CoCreateInstance。
CoCreateInstance將使用此接口來調用IClassFactory::CreateInstance函數
IClassFactory::CreateInstance調用了new操作符來創建指定的組件，並查詢組件的IX接口。

//客戶調用COM流程：
CoCreateInstace(rclsid,NULL,dwClsContext,IID_IX,(void**)&pIX);    //IX* pIX
    |--> CoGetClassObject(rclsid, dwClsContext, NULL, IID_IClassFactory, &pCF)    //IClassFactory* pCF
        |--> DllGetClassObject(rclsid,IID_IClassFactory,&pCF)    
            |--> CFactory* pFactory = new CFactory();
            |--> pFactory->QueryInterface(IID_IClassFactory,&pCF);    //返回類場指針IClassFactory* pCF
    |--> pCF->CreateInstance(pUnkOuter, IID_IX, &pIX);    //IX* pIX 組件接口指針pIX
pIX->Fx();

注意：.def模塊定義文件

LIBRARY    "ComComponent"

EXPORTS
    DllCanUnloadNow　　PRIVATE
    DllGetClassObject　  PRIVATE
    DllRegisterServer　　PRIVATE
    DllUnregisterServer　PRIVATE