提前对太长的帖子表示抱歉，但考虑到涉及的部分很多，我不确定我会在哪里犯错，因此，我需要发布所有涉及的部分。请不要假设任何事情，我可能会在这里犯任何类型的错误。
问题：
1）真正的问题：刚刚学习COM。
2) 我需要将 IDispatch 指针从 C++ 中的控制台客户端 ( ConsoleClient ) 作为参数传递给 Windows 服务 ( WinService ) 中的 COM 函数。此 IDispatch 指针充当回调。WinService 知道要调用的函数的名称。我所有的尝试都没有成功。我收到不同的错误，例如：未实现、RPC 不可用等。
注意：以下错误是正确的！我在@Igor 指出我的错误后进行了编辑：在 STA 线程中有一个 do-while（我从 main() 中删除）。我在 main() 线程（而不是 do-while）中添加了一个消息泵（GetMessage、TranslateMessage 和 DispatchMessage），我的问题得到了解决！
我有一个 WinService 公开以下 COM 接口（WinService 的 idl 文件）：
[
object,
uuid(DBE8BC31-9D2B-4F4B-903A-B40473408DE9),
dual,
nonextensible,
pointer_default(unique)
]
interface IWinService : IDispatch
{
///Here there are more functions..
[id(4), helpstring("Interface HELP")]
HRESULT WinServiceCOMfunction( [in] VARIANT vCallback, [out, retval] LONG* pReturn );
//Here there even more functions...
};
[
uuid(DEF3BFAE-ADF4-493B-8D01-E47A279225C5),
version(1.0),
helpstring("LIB HELP")
]
library WinServiceLib
{
importlib("stdole2.tlb");
[
uuid(AC290DC9-8CB4-4502-A73C-2BDAEC4B215A)
]
coclass CoWinService
{
[default] interface IWinService;
};
}
WinService 内部期望vCallBack .vt = VT_DISPATCH，即当我从 ConsoleClient.EXE 应用程序调用 WinServiceCOM 函数时需要传入的回调指针。WinService 知道充当回调的函数的名称。即，WinService 从IDispatch-pointer-callback GetIDsOfName 调用以“ FunctionCallback ”作为参数。但是，在这里我在 WinService 中遇到不同的错误，例如：未实现，RPC 不可用等。然后没有执行回调（ConsoleClient 没有收到任何返回）。
到目前为止我所做的（以下所有源代码都在 ConsoleClient.EXE 中找到）ConsoleClient.EXE main.cpp：
int _tmain(int argc, _TCHAR* argv[])
{
CoInitialize(NULL);
//To be brief: Let's think that I already have an IDispatch pointer to the WinService interface IWinService:
CComPtr<IDispatch> pIWinService; //pIWinService
//Here I queried the IWinService interface...It was successful!!!
OLECHAR * winServiceNameFunction = L"WinServiceCOMfunction";
DISPID dispid;
hr = pIWinService->GetIDsOfNames( IID_NULL, &winServiceNameFunction, 1, LOCALE_USER_DEFAULT, &dispid );
if ( FAILED( hr ) )
{
wprintf( L"GetIDsOfNames failed" );
return 1;
}
else
{
wprintf( L"GetIDsOfNames succeeded!" );
}
CComPtr<IDispatch> consoleClientCallback( new CConsoleClientInterface() );
CConsoleClientInterface *sanity = dynamic_cast<CConsoleClientInterface *>( consoleClientCallback.p );
if ( nullptr == pAutoCallback )
{
wprintf( L"CConsoleClientInterface pointer failed\n" );
return 1;
}
else
{
wprintf( L"CConsoleClientInterface pointer succeeded\n" );
}
DWORD dwRegister;
hr = CoRegisterClassObject(CLSID_CoConsoleClient, consoleClientCallback.p,
CLSCTX_LOCAL_SERVER, REGCLS_MULTIPLEUSE, &dwRegister);
if(FAILED(hr))
{
wprintf(L"CoRegisterClassObject Failed\n");
return 1;
}
else
{
wprintf(L"CoRegisterClassObject Succeeded\n");
}
CComVariant paramCallback( consoleClientCallback.Detach() );
VARIANTARG varParams[] = { paramCallback };
DISPPARAMS dispparams = { vArgs, NULL, 1, 0 };
hr = pPtr->Invoke(
dispid,
IID_NULL,
LOCALE_SYSTEM_DEFAULT,
DISPATCH_METHOD,
&dispparams,
NULL,
NULL,
NULL);
if ( FAILED( hr ) )
{
wprintf( L"Invoke failed" );
return 1;
}
else
{
wprintf( L"Invoke Succeeded" );
}
MSG msg;
while(GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
CoRevokeClassObject(dwRegister);
CoUninitialize();
return 0;
}
所有主要的都成功执行。但是，我从来没有从回调中得到任何东西。当 WinService 尝试从 IDispatch 指针回调中查询接口时，它会抛出以下错误：未实现，RPC 不可用，等等......
创建 ConsoleClient IDispatch 接口的模板类来自：http: //blogs.msdn.com/b/oldnewthing/archive/2013/06/12/10425215.aspx
disInterfaceBase.h：
template<typename DispInterface>
class CDispInterfaceBase : public DispInterface
{
public:
CDispInterfaceBase() : m_cRef(1), m_dwCookie(0) { }
/* IUnknown */
IFACEMETHODIMP QueryInterface(REFIID riid, void **ppv)
{
*ppv = nullptr;
HRESULT hr = E_NOINTERFACE;
if (riid == IID_IUnknown || riid == IID_IDispatch ||
riid == __uuidof(DispInterface))
{
*ppv = static_cast<DispInterface *>
(static_cast<IDispatch*>(this));
AddRef();
hr = S_OK;
}
return hr;
}
IFACEMETHODIMP_(ULONG) AddRef()
{
return InterlockedIncrement(&m_cRef);
}
IFACEMETHODIMP_(ULONG) Release()
{
LONG cRef = InterlockedDecrement(&m_cRef);
if (cRef == 0) delete this;
return cRef;
}
// *** IDispatch ***
IFACEMETHODIMP GetTypeInfoCount(UINT *pctinfo)
{
*pctinfo = 0;
return E_NOTIMPL;
}
IFACEMETHODIMP GetTypeInfo(UINT iTInfo, LCID lcid,
ITypeInfo **ppTInfo)
{
*ppTInfo = nullptr;
return E_NOTIMPL;
}
IFACEMETHODIMP GetIDsOfNames(REFIID, LPOLESTR *rgszNames,
UINT cNames, LCID lcid,
DISPID *rgDispId)
{
return E_NOTIMPL;
}
IFACEMETHODIMP Invoke(
DISPID dispid, REFIID riid, LCID lcid, WORD wFlags,
DISPPARAMS *pdispparams, VARIANT *pvarResult,
EXCEPINFO *pexcepinfo, UINT *puArgErr)
{
if (pvarResult) VariantInit(pvarResult);
return SimpleInvoke(dispid, pdispparams, pvarResult);
}
// Derived class must implement SimpleInvoke
virtual HRESULT SimpleInvoke(DISPID dispid,
DISPPARAMS *pdispparams, VARIANT *pvarResult) = 0;
public:
HRESULT Connect(IUnknown *punk)
{
HRESULT hr = S_OK;
CComPtr<IConnectionPointContainer> spcpc;
if (SUCCEEDED(hr)) {
hr = punk->QueryInterface(IID_PPV_ARGS(&spcpc));
}
if (SUCCEEDED(hr)) {
hr = spcpc->FindConnectionPoint(__uuidof(DispInterface), &m_spcp);
}
if (SUCCEEDED(hr)) {
hr = m_spcp->Advise(this, &m_dwCookie);
}
return hr;
}
void Disconnect()
{
if (m_dwCookie) {
m_spcp->Unadvise(m_dwCookie);
m_spcp.Release();
m_dwCookie = 0;
}
}
private:
LONG m_cRef;
CComPtr<IConnectionPoint> m_spcp;
DWORD m_dwCookie;
};
ConsoleClient ConsoleClient.h 中的实际 IDispatch 实现
class CConsoleClientInterface : public CDispInterfaceBase<ICONSOLEINTERFACE>
{
public:
CConsoleClientInterface() { }
~CConsoleClientInterface() { }
STDMETHODIMP GetIDsOfNames(REFIID, LPOLESTR *rgszNames,
UINT cNames, LCID lcid,
DISPID *rgDispId)
{
HRESULT hr = E_FAIL;
if(_wcsicmp(*rgszNames, L"FunctionCallback") == 0)
{
*rgDispId = 1;
hr= S_OK;
}
else
{
hr= DISP_E_UNKNOWNINTERFACE;
}
if(FAILED(hr))
{
std::cout << L"FAILED\n";
}
return hr;
}
HRESULT SimpleInvoke(
DISPID dispid, DISPPARAMS *pdispparams, VARIANT *pvarResult)
{
// switch (dispid)
// {
// case 4:
std::cout << L"SimpleInvoke" << std::endl; //This is never printed (for the error that I am trying to figure out)
HRESULT hr = FunctionCallback( pdispparams->rgvarg[1].intVal, pdispparams->rgvarg[0].parray );
// break;
// }
return hr;
}
HRESULT FunctionCallback( LONG longValue, LPSAFEARRAY safearray )
{
//So simple, I just want that this value is printed in the ConsoleClient's console! Unfortunately this is not happening!
std::cout << longValue << std::endl;
return S_OK;
}
};
和 ConsoleClient.idl
[
object,
uuid(CD08B160-558A-4251-885C-173A08A461F1),
dual,
nonextensible,
helpstring("ICONSOLEINTERFACE Interface"),
pointer_default(unique)
]
interface ICONSOLEINTERFACE : IDispatch{
[id(1), helpstring("method FunctionCallback")]
HRESULT FunctionCallback([in] LONG longValue, [in] LPSAFEARRAY safeArray );
};
[
uuid(F3445A9E-555B-4729-952B-8B72B8DB2E37),
version(1.0),
helpstring("ConsoleClientLib Help Lib")
]
library ConsoleClientLib
{
importlib("stdole2.tlb");
[
uuid(EFF9EC78-3031-4558-9BA3-5B2641CCB304),
helpstring("CoConsoleClient Class")
]
coclass ConsoleClientInterface
{
[default] interface ICONSOLEINTERFACE;
};
};
我创造了：
HKEY_CLASSES_ROOT\CLSID\{EFF9EC78-3031-4558-9BA3-5B2641CCB304} //CLSID
(Default) REG_SZ = C:\Program Files\Common Files\ConsoleClient.EXE
HKEY_CLASSES_ROOT\CLSID\{EFF9EC78-3031-4558-9BA3-5B2641CCB304}\LocalServer32
ThreadingModel REG_SZ = Both
我还使用 regtlibv12.exe 注册了 tlb
很抱歉这篇文章太长了，但是 COM 强迫我这样做，特别是我是 COM 的新手，我不知道我会在哪里犯错。
注意：我确信调用（从 ConsoleClient.EXE）到 WinService COM 函数（WinServiceCOMfunction）是成功的（我调试了它并在调用之后点击了这个函数）。
NOTE2：我确信使用回调的 WinService 有效。还有其他实现（在不同的编程语言中）通过 WinService 中的相同功能（WinServiceCOMfunction）使用此机制。
有什么帮助吗？提前致谢！