def _load_streams(self):
        """
        Reads, parses and creates streams specified in config.yaml.
        """
        common_err_msg = 'No valid {} stream configurations found. '
        specific_err_msg = {'inbound': 'No data will be received (or displayed).',
                            'outbound': 'No data will be published.'}
        err_msgs = {}

        for stream_type in ['inbound', 'outbound']:
            err_msgs[stream_type] = common_err_msg.format(stream_type) + specific_err_msg[stream_type]
            streams = ait.config.get('server.{}-streams'.format(stream_type))

            if streams is None:
                log.warn(err_msgs[stream_type])
            else:
                for index, s in enumerate(streams):
                    try:
                        if stream_type == 'inbound':
                            strm = self._create_inbound_stream(s['stream'])
                            if type(strm) == PortInputStream:
                                self.servers.append(strm)
                            else:
                                self.inbound_streams.append(strm)
                        elif stream_type == 'outbound':
                            strm = self._create_outbound_stream(s['stream'])
                            self.outbound_streams.append(strm)
                        log.info('Added {} stream {}'.format(stream_type, strm))
                    except Exception:
                        exc_type, value, tb = sys.exc_info()
                        log.error('{} creating {} stream {}: {}'.format(exc_type,
                                                                        stream_type,
                                                                        index,
                                                                        value))
        if not self.inbound_streams and not self.servers:
            log.warn(err_msgs['inbound'])

        if not self.outbound_streams:
            log.warn(err_msgs['outbound'])
Reads, parses and creates streams specified in config.yaml.