// Engine (out of process COM singleton)

class ATL_NO_VTABLE CEngine :
    public CComObjectRootEx<CComSingleThreadModel>,
    public CComCoClass<CEngine, &CLSID_Engine>,
    public IDispatchImpl<IEngine, &IID_IEngine, &LIBID_EngineLib, /*wMajor =*/ 1, /*wMinor =*/ 0>
{
    
    DECLARE_CLASSFACTORY_SINGLETON(CEngine)
    
    STDMETHOD(dispatchEvent)(BSTR name, IDispatch* pEvent, VARIANT_BOOL* pbSuccess)
    {
        // pEvent is CPropertyStore instance
        ActiveScriptDispatch.Invoke1(L"FuncName", pEvent, &varResult);
    }
}


// BHO

class CPropertyStore :
    public CComObjectRootEx<CComSingleThreadModel>,
    public CComCoClass<CPropertyStore, &CLSID_NULL>,
    public IDispatch
{
    BEGIN_COM_MAP(CPropertyStore)
        COM_INTERFACE_ENTRY(IUnknown)
        COM_INTERFACE_ENTRY(IDispatch)
    END_COM_MAP()
    
    BOOL SetProperty(CString strName, VARIANT *value)
    {
        // Store value in CAtlArray
    }
    
    // IDispatch impl
    STDMETHOD(GetTypeInfoCount)(UINT *pctinfo);
    STDMETHOD(GetTypeInfo)(UINT iTInfo, LCID lcid, ITypeInfo **ppTInfo);
    STDMETHOD(GetIDsOfNames)(REFIID riid, LPOLESTR *rgszNames, UINT cNames, LCID lcid, DISPID *rgDispId);
    STDMETHOD(Invoke)(DISPID dispIdMember, REFIID riid, LCID lcid, WORD wFlags, DISPPARAMS *pDispParams, 
        VARIANT *pVarResult,EXCEPINFO *pExcepInfo, UINT *puArgErr);
}

class ATL_NO_VTABLE CBHO :
    public CComObjectRootEx<CComSingleThreadModel>,
    public CComCoClass<CBHO, &CLSID_BHO>,
    public IObjectWithSiteImpl<CBHO>,
    public IDispatchImpl<IBHO, &IID_IBHO, &LIBID_Lib, /*wMajor =*/ 1, /*wMinor =*/ 0>,
    public IDispEventImpl<1, CBHO, &DIID_DWebBrowserEvents2, &LIBID_SHDocVw, 1, 0>
{
    void onEvent(...)
    {
        if(m_pEngine == NULL && SUCCEEDED(m_pEngine.CoCreateInstance(CLSID_Engine)))
        {
            CComObject<CPropertyStore> *pEvent = NULL;
            HRESULT hRes = CComObject<CPropertyStore>::CreateInstance(&pEvent);

            CComVariant varEvent(pEvent);
            CComVariant varName(L"EventName");
            CComVariant varResult;

            m_pEngine.Invoke2(L"dispatchEvent", &varName, &varEvent, &varResult);
        }
    }
}