Using the Connection Manager

#pragma once
#include <connmgr_status.h>

// Bonus!
// This WTL class can be added to any CWindowImpl<> derived Window (as in the 
// example below) to be notified of any changes in the connection manager 
// status.
//
// class CMyWindow : public CWindowImpl< CMyWindow >, 
//                   // ...
//                   public CMStatusChangeWindow< CMyWindow >
// {
// public:
//     BEGIN_MSG_MAP( CMyWindow )
//         // ...
//         CHAIN_MSG_MAP( CMStatusChangeWindow< CMyWindow > )
//     END_MSG_MAP()
// 
//     void OnStatusChange( DWORD status )
//     {
//         // Alert! The Connection Manager status has changed.
//     };
// }; // class CMyWindow 
//

/// @brief sent by connection manager to indicate a change in status
/// @param WPARAM wParam - [DWORD] new status
/// @param LPARAM lParam - unused.
static const UINT UWM_CM_STATUS_CHANGE = 
    ::RegisterWindowMessage( CONNMGR_STATUS_CHANGE_NOTIFICATION_MSG );

/// A window that listens for connection manager status change notifications
template< class T >
class CMStatusChangeWindow
{
public:
    BEGIN_MSG_MAP( CMStatusChangeWindow< T > )
        MESSAGE_HANDLER( WM_CREATE, OnCreate )
        MESSAGE_HANDLER( UWM_CM_STATUS_CHANGE, OnCMStatusChange )
        MESSAGE_HANDLER( WM_DESTROY, OnDestroy )
    END_MSG_MAP()

    LRESULT OnCreate( UINT /*uMsg*/, 
                      WPARAM /*wParam*/, 
                      LPARAM /*lParam*/, 
                      BOOL& bHandled )
    {
        bHandled = FALSE;
        T* pT = static_cast< T* >( this );
        ::ConnMgrRegisterForStatusChangeNotification( TRUE, pT->m_hWnd );
        return 0;
    };

    LRESULT OnDestroy( UINT /*uMsg*/, 
                       WPARAM /*wParam*/, 
                       LPARAM /*lParam*/, 
                       BOOL& bHandled )
    {
        bHandled = FALSE;
        T* pT = static_cast< T* >( this );
        ::ConnMgrRegisterForStatusChangeNotification( FALSE, pT->m_hWnd );
        return 0;
    };

    LRESULT OnCMStatusChange( UINT /*uMsg*/, 
                              WPARAM wParam, 
                              LPARAM /*lParam*/, 
                              BOOL& /*bHandled*/ )
    {
        T* pT = static_cast< T* >( this );
        pT->OnStatusChange( static_cast< DWORD >( wParam ) );
        return 0;
    };

    void OnStatusChange( DWORD status )
    {
        // must be implemented in a derived class
        ASSERT( FALSE );
    };
}; // class CMStatusChangeWindow