Retrieves a Message.
int GetMessage(const QString& qsid);
This method retrieves a message.
Information about the retrieved message can be accessed through MessageInfo collection.
This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)