Re: trailers and pseudo-headers

[Julian Reschke <[e-mail]>]

On 2014-07-02 13:12, Michael Sweet wrote:
> Julian,
>
> On Jul 2, 2014, at 3:43 AM, Julian Reschke <[e-mail]> wrote:
>> On 2014-07-02 09:35, Poul-Henning Kamp wrote:
>>> In message <[e-mail]>, Julian Reschke writes:
>>>
>>>> The reason I ask is that people might start putting ":status" into a
>>>> trailer and expect that to have an effect (it would be nice to have that
>>>> feature, but it wouldn't map to 1.1...).
>>>
>>> It would also be pretty pointless:  It would just shift the buffering
>>> responsibility from the server to the client.
>>
>> What I meant is: an *additional* :status (such as in first claiming everything is ok -- 200, then start streaming and failing, and then send a 500 in the trailers).
>
> As you've noted, you can't do that in HTTP/1.1, and in fact this would be a case where I would emit 100 (continue) to the client to let them know they can continue sending data, then follow up with a final status code (200, 500, whatever) once I'd processed the message body and any trailers in the request.

When I said "streaming" I was referring to the process of sending the 
payload in the response.

There are many cases where a server would say "200", and then start a 
complicated process that might fail half-way. In HTTP/1.1, signalling an 
error in this situation is hard (abort the chunked transfer or close the 
connection). It would be good if HTTP/2 can do better here.

Best regards, Julian