[httpapi] RateLimit Header client implementations

[Darrel Miller <[e-mail]>]

Hey Roberto,

Do you have links to implementations of client applications that use some variant of the rate-limiting headers?
I know there are plenty of examples of server side implementations that will return these headers, but I am finding very few examples of clients taking advantage of these headers.

>From what I understand there are a few scenarios where clients can use these headers:


  1.  Optimizing polling frequency:  i.e. check quota and window and determine optimum calling interval
  2.  Prioritization between client tasks:  Don’t let low priority tasks starve high priority tasks of quota
  3.  Enable user agents to avoid hitting rate limit due to some kind of punitive behavior.

Are you aware of other scenarios?  Are there implementations of these scenarios?

While reviewing the goals for the draft I was wondering if they could be improved.


  *   The goals of this proposal are:
  *
  *   1. Standardizing the names and semantic of rate-limit headers;
  *   2. Improve resiliency of HTTP infrastructures simplifying the enforcement and the adoption of rate-limit headers;
  *   3. Simplify API documentation avoiding expliciting rate-limit fields semantic in documentation.

The second goal seems only indirectly related to what the draft actually enables.  A phrase in the introduction paragraph seems like a more accurate goal:


  *   communicate service quotas so that the client can throttle its requests and prevent 4xx or 5xx responses.

I also thing the third goal would be clearer stated as:

  *   Simplify API documentation by eliminating the need to define custom quota related header fields.

Darrel