Create a MessageHandler for the configured Encoder
        :param message_handlers: a dictionart of MessageHandler keyed by encoder
        :return: a MessageHandler

def get_message_handler(self, message_handlers):
        """
        Create a MessageHandler for the configured Encoder
        :param message_handlers: a dictionart of MessageHandler keyed by encoder
        :return: a MessageHandler
        """
        encoder = self.options.encoder
        try:
            return message_handlers[encoder]
        except KeyError:
            raise NotImplementedError('No RequestHandler defined for given encoder (%s).' % encoder)