Extensions

Per-Message Deflate

websockets.extensions.permessage_deflate implements the Compression Extensions for WebSocket as specified in RFC 7692.

class websockets.extensions.permessage_deflate.ClientPerMessageDeflateFactory(server_no_context_takeover: bool = False, client_no_context_takeover: bool = False, server_max_window_bits: Optional[int] = None, client_max_window_bits: Optional[Union[int, bool]] = None, compress_settings: Optional[Dict[str, Any]] = None)[source]

Client-side extension factory for the Per-Message Deflate extension.

Parameters behave as described in section 7.1 of RFC 7692. Set them to True to include them in the negotiation offer without a value or to an integer value to include them with this value.

Parameters

  • server_no_context_takeover – defaults to False

  • client_no_context_takeover – defaults to False

  • server_max_window_bits – optional, defaults to None

  • client_max_window_bits – optional, defaults to None

  • compress_settings – optional, keyword arguments for zlib.compressobj(), excluding wbits

class websockets.extensions.permessage_deflate.ServerPerMessageDeflateFactory(server_no_context_takeover: bool = False, client_no_context_takeover: bool = False, server_max_window_bits: Optional[int] = None, client_max_window_bits: Optional[int] = None, compress_settings: Optional[Dict[str, Any]] = None)[source]

Server-side extension factory for the Per-Message Deflate extension.

Parameters behave as described in section 7.1 of RFC 7692. Set them to True to include them in the negotiation offer without a value or to an integer value to include them with this value.

Parameters

  • server_no_context_takeover – defaults to False

  • client_no_context_takeover – defaults to False

  • server_max_window_bits – optional, defaults to None

  • client_max_window_bits – optional, defaults to None

  • compress_settings – optional, keyword arguments for zlib.compressobj(), excluding wbits

Abstract classes

class websockets.extensions.Extension[source]

Abstract class for extensions.

decode(frame: websockets.frames.Frame, *, max_size: Optional[int] = None) → websockets.frames.Frame[source]

Decode an incoming frame.

Parameters

  • frame – incoming frame

  • max_size – maximum payload size in bytes

encode(frame: websockets.frames.Frame) → websockets.frames.Frame[source]

Encode an outgoing frame.

Parameters

frame – outgoing frame

name

Extension identifier.

class websockets.extensions.ClientExtensionFactory[source]

Abstract class for client-side extension factories.

get_request_params() → List[Tuple[str, Optional[str]]][source]

Build request parameters.

Return a list of (name, value) pairs.

name

Extension identifier.

process_response_params(params: Sequence[Tuple[str, Optional[str]]], accepted_extensions: Sequence[websockets.extensions.base.Extension]) → websockets.extensions.base.Extension[source]

Process response parameters received from the server.

Parameters

  • params – list of (name, value) pairs.

  • accepted_extensions – list of previously accepted extensions.

Raises

NegotiationError – if parameters aren’t acceptable

class websockets.extensions.ServerExtensionFactory[source]

Abstract class for server-side extension factories.

name

Extension identifier.

process_request_params(params: Sequence[Tuple[str, Optional[str]]], accepted_extensions: Sequence[websockets.extensions.base.Extension]) → Tuple[List[Tuple[str, Optional[str]]], websockets.extensions.base.Extension][source]

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 Extension

Parameters

  • params – list of (name, value) pairs.

  • accepted_extensions – list of previously accepted extensions.

Raises

NegotiationError – to reject the offer, if parameters aren’t acceptable