- permessage-deflate PARAMETERSprocedure
To offer to use this extension during the opening handshake, supply (list (permessage-deflate PARAMETERS)) as an optional argument to ws-connect.
The argument PARAMETERS should be a list in which each item is an alist, each of whose items is in turn a pairs of strings (PARAMETER . VALUE) or a pair of form (PARAMETER . #t). These specify the parameters to be advertised during the opening handshake.
For example, to ask the server to use an LZ77 sliding window of length no greater than 1024, but to fall back to permessage-deflate without this parameter if the server does not support it, one might specify
'((("server_max_window_bits" . "10")) ())
so that the Sec-WebSocket-Extensions header in the client opening handshake will contain the string