Source code for websockets.extensions.base

"""
:mod:`websockets.extensions.base` defines abstract classes for implementing
extensions.

See `section 9 of RFC 6455`_.

.. _section 9 of RFC 6455: http://tools.ietf.org/html/rfc6455#section-9

"""

from typing import List, Optional, Sequence, Tuple

from ..framing import Frame
from ..typing import ExtensionParameter


__all__ = ["Extension", "ClientExtensionFactory", "ServerExtensionFactory"]


[docs]class Extension: """ Abstract class for extensions. """ @property def name(self) -> str: """ Extension identifier. """
[docs] def decode(self, frame: Frame, *, max_size: Optional[int] = None) -> Frame: """ Decode an incoming frame. :param frame: incoming frame :param max_size: maximum payload size in bytes """
[docs] def encode(self, frame: Frame) -> Frame: """ Encode an outgoing frame. :param frame: outgoing frame """
[docs]class ClientExtensionFactory: """ Abstract class for client-side extension factories. """ @property def name(self) -> str: """ Extension identifier. """
[docs] def get_request_params(self) -> List[ExtensionParameter]: """ Build request parameters. Return a list of ``(name, value)`` pairs. """
[docs] def process_response_params( self, params: Sequence[ExtensionParameter], accepted_extensions: Sequence[Extension], ) -> Extension: """ Process response parameters received from the server. :param params: list of ``(name, value)`` pairs. :param accepted_extensions: list of previously accepted extensions. :raises ~websockets.exceptions.NegotiationError: if parameters aren't acceptable """
[docs]class ServerExtensionFactory: """ Abstract class for server-side extension factories. """ @property def name(self) -> str: """ Extension identifier. """
[docs] def process_request_params( self, params: Sequence[ExtensionParameter], accepted_extensions: Sequence[Extension], ) -> Tuple[List[ExtensionParameter], Extension]: """ Process request parameters received from the client. To accept the offer, return a 2-uple containing: - response parameters: a list of ``(name, value)`` pairs - an extension: an instance of a subclass of :class:`Extension` :param params: list of ``(name, value)`` pairs. :param accepted_extensions: list of previously accepted extensions. :raises ~websockets.exceptions.NegotiationError: to reject the offer, if parameters aren't acceptable """