code: def acquire_connection(settings, tag=None, logger_name=None, auto_commit=False):
          
          try:
              connection_properties = settings.get(tag, settings[None])
          except KeyError:
              raise RdbmsConnection.DefaultConnectionPropertiesSettingException()
  
          return RdbmsConnection(
              connection_properties['rdbms_hostname'],
              connection_properties['rdbms_port'],
              connection_properties['rdbms_database_name'],
              connection_properties['rdbms_account_username'],
              connection_properties['rdbms_account_password'],
              logger_name=logger_name,
              auto_commit=auto_commit)
docs: Return a connection to a Relational DataBase Management System (RDBMS)
          the most appropriate for the service requesting this connection.
  
          @param settings: a dictionary of connection properties::
                     {
                       None: {
                         'rdbms_hostname': "...",
                         'rdbms_port': ...,
                         'rdbms_database_name': "...",
                         'rdbms_account_username': '...'
                         'rdbms_account_password': '...'
                       },
                       'tag': {
                         'rdbms_hostname': "...",
                         'rdbms_port': ...,
                         'rdbms_database_name': "...",
                         'rdbms_account_username': '...'
                         'rdbms_account_password': '...'
                       },
                       ...
                     }
                 The key ``None`` is the default tag.
  
          @param tag: a tag that specifies which particular connection
             properties has to be used.
  
          @param logger_name: name of the logger for debug information.
  
          @param auto_commit: indicate whether the transaction needs to be
             committed at the end of the session.
  
          @return: a ``RdbmsConnection`` instance to be used supporting the
               Python clause ``with ...:``.
  
          @raise DefaultConnectionPropertiesSettingException: if the specified
                 tag is not defined in the dictionary of connection properties,
                 and when no default connection properties is defined either
                 (tag ``None``).