c++ - 如何检查容器是否支持多连接？

Question

• 实现了 Sink 类 - 从 COM 服务器接收事件通知
• 事件接口(interface)派生自 IDispatch

我遇到一个问题，即 IConnectionPoint::Advise 调用返回 E_NOTIMPL。这可能是因为连接点 只允许一个连接 - MSDN .

注意:

• COM 服务器处于进程外
• 纯 C++ 实现

编辑:

S8.tlh:与 Win32 类型库 S8.tlb 等效的 C++ 源代码:

struct __declspec(uuid("090910c3-28c3-45fe-861d-edcf11aa9788"))
IS8SimulationEvents : IDispatch
{

    // Methods:
    HRESULT S8SimulationReset ( );
    HRESULT S8SimulationEndRun ( );
    HRESULT S8SimulationCustomEvent (
        BSTR * TextInfo );
    HRESULT S8SimulationOpened ( );
    HRESULT S8SimulationEndTrial ( );
    HRESULT S8SimulationOEMEvent (
        BSTR * TextInfo );
    HRESULT S8SimulationReadyToClose ( );
    HRESULT S8SimulationUserMessage (
        long * Answer,
        BSTR * TextMsg,
        long ValidAnswers );
};

Class Sink 的实现 - 处理事件通知:

class Sink : public IS8SimulationEvents
{
public:
Sink(){
    m_dwRefCount = 0;
};
~Sink(){};
/*
* IS8SimulationEvent interface functions
*/
HRESULT S8SimulationEndTrial()
{
    cout << "Simulation complete." << endl;
    return S_OK;;
};

HRESULT S8SimulationOpened()
{
    cout << "Simulation open." << endl;
    return S_OK;
};

HRESULT S8SimulationReadyToClose()
{
    cout << "Simulation ready to close" << endl;
    return S_OK;
};

ULONG STDMETHODCALLTYPE AddRef()
{
    m_dwRefCount++;
    return m_dwRefCount;
};

ULONG STDMETHODCALLTYPE Release()
{
    ULONG l;
    l = m_dwRefCount--;

    if (0 == m_dwRefCount)
    {
        delete this;
    }

    return m_dwRefCount;
};

HRESULT STDMETHODCALLTYPE QueryInterface(
                                        REFIID iid ,
                                        void **ppvObject)
{
    m_dwRefCount++;
    *ppvObject = (void *)this;
    return S_OK;
};

HRESULT STDMETHODCALLTYPE GetTypeInfoCount(UINT *pctinfo)
{
    return E_NOTIMPL;
};

HRESULT STDMETHODCALLTYPE GetIDsOfNames( 
                                        REFIID riid,
                                        LPOLESTR *rgszNames,
                                        UINT cNames,
                                        LCID lcid,
                                        DISPID *rgDispId)
{
    return E_NOTIMPL;
};

HRESULT STDMETHODCALLTYPE GetTypeInfo(
                                    unsigned int iTInfo,
                                    LCID lcid,
                                    ITypeInfo FAR* FAR* ppTInfo)
{
    return E_NOTIMPL;
};

HRESULT STDMETHODCALLTYPE Invoke(
                                DISPID dispIdMember,
                                REFIID riid,
                                LCID lcid,
                                WORD wFlags,
                                DISPPARAMS FAR* pDispParams,
                                VARIANT FAR* pVarResult,
                                EXCEPINFO FAR* pExcepInfo,
                                unsigned int FAR* puArgErr)
{
    HRESULT hresult = S_OK;
    if (pDispParams)
    {
        switch (dispIdMember) {
        case 1:
            return S8SimulationEndTrial();
        case 2:
            return S8SimulationOpened();
        case 3:
            return S8SimulationReadyToClose();
        default:
            return E_NOTIMPL;
        }

    }
    return E_NOTIMPL;
}
private:
    DWORD m_dwRefCount;
public:
void SetupConnectionPoint (IS8Simulation *pis8)
{

    HRESULT hresult;
    IConnectionPointContainer *pContainer = NULL;
    IConnectionPoint *pConnection = NULL;
    IUnknown *pSinkUnk = NULL;
    Sink *pSink = NULL;
    DWORD dwAdvise;

    dwAdvise = 0;

    hresult = pis8->QueryInterface(
                        __uuidof(IConnectionPointContainer),
                        (void **) &pContainer);

    if (SUCCEEDED(hresult))
    {
        cout << "IConnectionPointContainer inteface supported." << endl;
    } else {
        cerr << "Error: No such interface supported." << endl;
        exit (hresult);
    }

                                    __uuidof(IS8SimulationEvents),
                                    &pConnection); 

    switch (HRESULT_CODE(hresult)) {
        case NOERROR:
            cout << "Obtained valid interface pointer." << endl;
            break;
        case E_POINTER:
            cerr << "Invalid pointer: the address is not valid." << endl;
            exit (hresult);
            break;
        case CONNECT_E_NOCONNECTION:
            cerr << "This connectable object not support the "
                    "outgoing interface specified." << endl;
            exit (hresult);
            break;
        case E_UNEXPECTED:
        default:
            cerr << "Catastrophic failure." << endl;
            exit (hresult);
            break;
    }

    pContainer->Release();


    hresult = pSink->QueryInterface(
                            __uuidof(IUnknown),
                            (void **)&pSinkUnk);

    if (FAILED(hresult))
    {
        exit (EXIT_FAILURE);
    }

    hresult = pConnection->Advise(
                            pSinkUnk,
                            &dwAdvise);

    switch (HRESULT_CODE(hresult)) {
        case NOERROR:
            cout << "The connection has been established and "
                    "*dwAdvise has the connection token." << endl;
            break;
        case E_POINTER:
            cerr << "Invalid pointer: "
                    "the value pSinkUnk or dwAdvise is not valid." << endl;
            exit (hresult);
            break;
        case CONNECT_E_ADVISELIMIT:
            cerr << "The connection point has already reached "
                    "its limit of connections and cannot accept "
                    "any more." << endl;
            exit (hresult);
            break;
        case CONNECT_E_CANNOTCONNECT:
            cerr << "The sink does not support the interface "
                    "required by this connection point." << endl;
            exit (hresult);
            break;
        case E_NOTIMPL:
            break;
            case E_UNEXPECTED:
            default:
        cerr << "Catastrophic failure." << endl;
        exit (hresult);
        break;
    }
    return;
}
};

编辑:

Sink类中IUnknown接口(interface)的实现

ULONG STDMETHODCALLTYPE AddRef()
{
    m_dwRefCount++;
    return m_dwRefCount;
};

ULONG STDMETHODCALLTYPE Release()
{
    ULONG l;
    l = m_dwRefCount--;

    if (0 == m_dwRefCount)
    {
        delete this;
    }

    return m_dwRefCount;
};

HRESULT STDMETHODCALLTYPE QueryInterface(REFIID iid, void **ppvObject)
{
    m_dwRefCount++;
    *ppvObject = (void *)this;
    return S_OK;
};

问题:

• 如何检查容器是否支持多连接？
• 如果需要更多信息，请相应地发表评论。

Answer 1

请再次阅读 MSDN 文章。

 A connection point that allows only one interface
 can return E_NOTIMPL FROM the IConnectionPoint::EnumConnections method
EnumConnections : E_NOTIMPL 
The connection point does not support enumeration.

IConnectionPoint::Advise 需要回复

CONNECT_E_ADVISELIMIT

当他的连接点已经达到其连接限制并且不能再接受时。

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