The compression dictionary transport specification has moved to the IETF: Compression Dictionary Transport
These are the changes that have been made to the specs as it has progressed through various standards organizations and based on developer feedback during browser experiments.
- The
dictionary
link relation type was changed tocompression-dictionary
. - The
br-d
content encoding changed todcb
and a header with the hash of the dictionary was added to the stream. - The
zstd-d
content encoding changed todcz
and a header with the hash of the dictionary was added to the stream.
- The
Sec-Available-Dictionary
request header changed toAvailable-Dictionary
. - The value of the
Available-Dictionary
request header changed to be a Structured Field Byte Sequence (base-64 encoding of the dictionary hash, surrounded by colons) instead of hex-encoded string. - The content encoding string for brotli with a dictionary changed from
sbr
tobr-d
. - The
match
field of theUse-As-Dictionary
response header is now a URLPattern. - The expiration of the dictionary now uses the cache expiration of the dictionary resource instead of a separate
expires
. - The server can provide an
id
in theUse-As-Dictionary
response header which is echoed in theDictionary-ID
request header by the client in future requests. - The server needs to send a
Content-Dictionary
response header with the hash of the dictionary used when compressing a response with a dictionary (must match theAvailable-Dictionary
from the request). match-dest
was added to theUse-As-Dictionary
response header to allow for matching on fetch destinations (e.g.match-dest=["document"]
and have the dictionary only be used for document requests).