IUPnPService::QueryStateVariable

This method returns the value of one of the service's state variables.

HRESULT QueryStateVariable(
  BSTR bstrVariableName,
  VARIANT* pvarValue
);

bstrVariableName
[in] Specifies the state variable for which to return a value. All variable names are case sensitive.
pvarValue
[out] Receives a reference to the value of the variable specified by bstrVariableName. The type of the data returned depends on the state variable for which the query was invoked.

Otherwise, the method returns either one of the COM error codes defined in WinError.h, or one of the following UPnP-specific return values.

UPnP-specific return value	Description
UPNP_E_DEVICE_ERROR	Variable is not evented and the remote query returned an error code. This is not a transport error; the device received the request, but it returned an error.
UPNP_E_DEVICE_TIMEOUT	The device has not responded within the 30–second time-out period.
UPNP_E_INVALID_VARIABLE	Variable does not exist.
UPNP_E_PROTOCOL_ERROR	Query was not completed because of problems at the UPnP protocol level.
UPNP_E_TRANSPORT_ERROR	Variable is not evented and the remote query for the value failed because of an HTTP problem. Use IUPnPService::LastTransportStatus to retrieve the HTTP error code.

The UPnP Forum discourages use of this method. If possible, use a service-specific action, if one has been provided.

OS Versions: Windows CE .NET 4.0 and later.
Header: Upnp.h.
Link Library: Uuid.lib.

Additional resources