Added support for policy identifier

[darrelmiller]

This proposal takes what we currently have in draft-07

RateLimit-Policy: 100;w=60, 10000;w=86400
{ 50 requests and 30 seconds}
RateLimit: limit=100, remaining=50, reset=30  // protection limit
{ 1 requests and 40 seconds}
RateLimit: limit=10000, remaining=90, reset=200 // quota limit

and suggests the following alternative

RateLimit-Policy: protection;l=100;w=60, quota;l=10000;w=86400
{ 50 requests and 30 seconds}
RateLimit: protection;r=50;t=30
{ 1 request and 40 seconds}
RateLimit: quota;r=90;t=200

This proposal introduces a policy "identifier" that connects the RateLimit field to the RateLimit-Policy field. The primary purpose is to address #127.

With the change in draft-07 to use structured fields in the header we now have the opportunity to explore different approaches and features without trying to maintain similarity with past efforts.

[nfriedly]

I'm a big fan of this overall, I think it's a solid improvement in terms of consistency and ease of parsing.

I am curious about the reasoning for separate RateLimit and RateLimit-Policy headers? It seems to me that the policy parameters could also be appended to the RateLimit header.

[darrelmiller]

I am curious about the reasoning for separate RateLimit and RateLimit-Policy headers? It seems to me that the policy parameters could also be appended to the RateLimit header.

The split is due to variability of the values and HTTP/2 HPACK compression. RateLimit-Policy should rarely change and therefore can be optimized by header compression. RateLimit will change on ever request and therefore will not be optimized.

[ioggstream]

make returns this error.

draft-ietf-httpapi-ratelimit-headers.xml(0): Error: IDREF attribute target references an unknown ID "ratelimit-reset-keyword", at None

[ioggstream]

@darrelmiller I tried to fix the broken section references: now it should build. Could you please PTAL?

[ioggstream]

@nfriedly PR welcome for fixing inconsistencies :)

[richsalz]

make returns this error.

draft-ietf-httpapi-ratelimit-headers.xml(0): Error: IDREF attribute target references an unknown ID "ratelimit-reset-keyword", at None

There's a few instances still to be cleaned up:

; grep -n ratelimit-reset-keyword *.md
draft-ietf-httpapi-ratelimit-headers.md:216:     the time window reset time ({{ratelimit-reset-keyword}}).
draft-ietf-httpapi-ratelimit-headers.md:233:- inferred by the value of the [reset keyword](#ratelimit-reset-keyword) at the moment of the reset, or
draft-ietf-httpapi-ratelimit-headers.md:263:## Reset Keyword {#ratelimit-reset-keyword}
draft-ietf-httpapi-ratelimit-headers.md:440:Consider that service limit might not be restored after the moment referenced by the [reset keyword](#ratelimit-reset-keyword),
draft-ietf-httpapi-ratelimit-headers.md:579:| RateLimit | reset                 | Dictionary Key |Quota reset interval | {{ratelimit-reset-keyword}} of {{&SELF}} |       |