Re: New I-D: Retry-Scope header field

Roberto Polli <> Wed, 27 May 2020 09:21 UTC

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From: Roberto Polli <>
Date: Wed, 27 May 2020 11:18:51 +0200
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To: Mark Nottingham <>
Cc: HTTP Working Group <>, Martin Thomson <>
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Subject: Re: New I-D: Retry-Scope header field
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Hi Mark,

thanks for your great feedback!

replies inline:

Il giorno mar 21 apr 2020 alle ore 09:22 Mark Nottingham
<> ha scritto:
> I don't know that it makes sense to put a different scope on retries;
> the only thing that's able to be retried is a request that's already been made
>  for 503, I [..] doubt that a browser is going to stop making requests [..] based upon the value of this header[...]
>  [W]hat you expect a consumer to do with this information?
During API interactions (eg. the UA is a machine)  applications or api
gateways usually return either 503 or 429 if the service is saturated,
overloaded or over-quota. In those cases the scope helps shaping the
api client behavior.

> Retry-After is also defined to be used by 413 Payload Too Large, and that doesn't make any sense to scope beyond the current request payload.
Agree, 413 is about _this_ request

> I _think_ the semantic you're looking for is attached to the status code (in the most obvious case, 503), not the Retry-After header.
Retry-After is defined for 429 too, see and this kind of usage
is quite similar to the one I intend.

> I wonder is whether there are other status codes that might be relevant -- i.e., whether one should just do a "scope a 503" header,
> or one for any potential status code. Of 5xx status codes, 503 is the only one that has an obvious fit.
While a `503-Scope` make sense, the fact that 429 refers to
Retry-After makes me lean on Retry-Scope.
I'll reference 429 it in the draft.

Spec link:


Thanks++ and let me know,