Establishing a Connection

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Establishing a Connection

Once the user selects a device, the ChooseDevice function, in turn, calls the IPortableDevice::Open method to establish a connection between the application and the device. The IPortableDevice::Open method takes two arguments:

• A pointer to a null-terminated string that specifies the Plug and Play name of the device. (This string is retrieved by calling the IPortableDeviceManager::GetDevices method.)
• A pointer to an IPortableDeviceValues interface that specifies client information for the application.

• // CoCreate the IPortableDevice interface and call Open() with
  // the chosen PnPDeviceID string.
  hr = CoCreateInstance(CLSID_PortableDevice,
                        NULL,
                        CLSCTX_INPROC_SERVER,
                        IID_IPortableDevice,
                        (VOID**) ppDevice);
  if (SUCCEEDED(hr))
  {
      if (ppDevice != NULL)
      {
          hr = (*ppDevice)->Open(pPnpDeviceIDs[uiCurrentDevice], pClientInformation);
          if (FAILED(hr))
          {
              printf("! Failed to Open the device, hr = 0x%lx\n",hr);
              // Release the IPortableDevice interface, because we cannot proceed
              // with an unopen device.
              (*ppDevice)->Release();
              *ppDevice = NULL;
          }
      }
      else
      {
          hr = E_UNEXPECTED;
          printf("! Failed to Open the device because we were returned a NULL IPortableDevice interface pointer, hr = 0x%lx\n",hr);
      }
  }
  else
  {
      printf("! Failed to CoCreateInstance CLSID_PortableDevice, hr = 0x%lx\n",hr);
  }
  

}

See Also

• Selecting a Device

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