Re: Multiple Huffman code tables

I have struggled with this conceptually when thinking about the QPACK
static table.

If a vast number of requests pass a 'branded' header, is it not in
everyone's best interests to include that information, to reduce
bytes-on-the-wire?

That's why we should have a standard where 'common' headers have predefined
positions in a static table, with separate versions of that table which can
be used by the various vendors to append their own branded headers (or
indeed, to have their own standalone static tables that include both their
branded headers and also only the very small subset of the total set of
possible headers that their devices may send or receive).

For example, the various voice assistants (Google Assistant, Amazon Alexa,
Apple Siri) only ever make requests to/from specified servers, so their
designers are very well aware of the best way to encode the headers used in
their transactions - both branded and not - to both reduce bytes
on-the-wire AND limit the memory usage by those client devices storing
QPACK/HPACK tables full of headers that they will never normally send or
receive.

On Fri, Dec 8, 2023 at 12:37 PM Christian Huitema <huitema@huitema.net>
wrote:

> I have no opinion on the benefits or not of defining better compression
> than HPACK/QPACK, but I do have an opinion on the inclusion of brands in
> the training set, like:
>
>
>  > -1, '"Google Chrome";v="117", "Not;A=Brand";v="8", "Chromium";v="117"'
>
>  > -1, '"Google Chrome";v="117.0.5938.89", "Not;A=Brand";v="8.0.0.0",
>  > "Chromium";v="117.0.5938.89"'
>
>  > -3, 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36
>  > (KHTML, like Gecko) Chrome/117.0.0.0 Safari/537.36'
>
>
>  > 0, '1P_JAR=2023-11-22-18; expires=Fri, 22-Dec-2023 18:46:19 GMT;
>  > path=/; domain=.google.com; Secure; SameSite=none'
>
> I assume that this kind of branded content reflects the reality of the
> market place, and that assigning short Huffman codes to it will indeed
> reduce the size of messages. But I think dedicating codes to such brands
> today is an error. Market shares and product names will change over
> time, making such optimizations ephemeral. But even if the optimizations
> were stable, optimizing for the existing set of brands will provide an
> advantage to these brands over newcomers, and thus contribute to
> increased concentration -- something that standards should certainly not
> encourage.
>
> -- Christian Huitema