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=False, client_no_context_takeover=False, server_max_window_bits=None, client_max_window_bits=None, compress_settings=None)

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 (bool) – defaults to False

• client_no_context_takeover (bool) – defaults to False

• server_max_window_bits (Optional[int]) – optional, defaults to None

• client_max_window_bits (Union[int, bool, None]) – optional, defaults to None

• compress_settings (Optional[Dict[str, Any]]) – optional, keyword arguments for zlib.compressobj(), excluding wbits

class websockets.extensions.permessage_deflate.ServerPerMessageDeflateFactory(server_no_context_takeover=False, client_no_context_takeover=False, server_max_window_bits=None, client_max_window_bits=None, compress_settings=None)

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 (bool) – defaults to False

• client_no_context_takeover (bool) – defaults to False

• server_max_window_bits (Optional[int]) – optional, defaults to None

• client_max_window_bits (Optional[int]) – optional, defaults to None

• compress_settings (Optional[Dict[str, Any]]) – optional, keyword arguments for zlib.compressobj(), excluding wbits

Abstract classes

class websockets.extensions.Extension

Abstract class for extensions.

decode(frame, *, max_size=None)

Decode an incoming frame.

Parameters:

• frame (Frame) – incoming frame

• max_size (Optional[int]) – maximum payload size in bytes

Return type:

Frame

encode(frame)

Encode an outgoing frame.

Parameters:

frame (Frame) – outgoing frame

Return type:

Frame

property name: ExtensionName

Extension identifier.

class websockets.extensions.ClientExtensionFactory

Abstract class for client-side extension factories.

get_request_params()

Build request parameters.

Return a list of (name, value) pairs.

Return type:

List[Tuple[str, Optional[str]]]

property name: ExtensionName

Extension identifier.

process_response_params(params, accepted_extensions)

Process response parameters received from the server.

Parameters:

• params (Sequence[Tuple[str, Optional[str]]]) – list of (name, value) pairs.

• accepted_extensions (Sequence[Extension]) – list of previously accepted extensions.

Raises:

NegotiationError – if parameters aren’t acceptable

Return type:

Extension

class websockets.extensions.ServerExtensionFactory

Abstract class for server-side extension factories.

property name: ExtensionName

Extension identifier.

process_request_params(params, accepted_extensions)

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 (Sequence[Tuple[str, Optional[str]]]) – list of (name, value) pairs.

• accepted_extensions (Sequence[Extension]) – list of previously accepted extensions.

Raises:

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

Return type:

Tuple[List[Tuple[str, Optional[str]]], Extension]