Re: Lifting HTTP/3 Features into Extensions

On 13/12/18 1:13 pm, Andy Green wrote:
> 
> On 13/12/2018 06:46, Adrien de Croy wrote:
>>
>> Anyone proposing moving features out to optional extensions would be
>> well advised to look at the history of IMAP, and the interop nightmare
>> that this approach causes.
>>
>> I think we need to take a good long look and make things we need
>> non-optional.  If something is truly optional then you have to be
>> prepared for it to cause interop problems, and you get a chicken and
>> egg problem, where client vendors won't add support for an option
>> unless a server vendor does, and vice versa. Making a feature optional
>> is a pretty good way to consign it to oblivion..
> 
> Yes... websockets has a similar story... extensions were used as a
> somewhat desperate measure to carve off subjects that didn't seem to
> have a good way to be resolved in the standard in the short term,
> multiplexing and compression.
> 
> Multiplexing on ws never happened, and came to fruition as h2.
> Compression happened but it is literally the only extension.  Most
> implementations of ws don't implement it.
> 
> When extensions come up as a solution it's maybe better to resist the
> urge to try to keep everyone happy and instead say either this fits with
> what we want to do and we will deal with it as a first-class citizen, or
> it is outside the scope of what we are doing.
> 
> In the case of trailers, IMHO they should be banned just like chunking
> was in h2 to simplify the protocol.  If intermediaries want to pass h1
> or h2 over h3 they can take care of fixing the trailers into headers
> just like h1 over h2 has to take care of stripping the chunking.
> 

While I like the simplicity this approach would bring to the header
handling there are some uses of Trailers for the general performance case.

The one which is most useful is TE:Content-MD5 delivering a hash of the
content/payload in a way cross-compatible with middleware translating
the HTTP versions or assisting with interop workarounds for those DATA
size issues that have been discussed recently.

Amos

Received on Thursday, 13 December 2018 16:45:24 UTC