Re: Introducing a new HTTP response header for Carbon Emissions calculation

> On 12 Apr 2023, at 12:10 am, Lucas Pardue <> wrote:
> Have you considered how this might work where there is a chain of servers involved in handling a request? We might think of CDNs in this light but it is also common for servers to sit in front of something like an app server or cache server. Therefore it could benefit this proposal to make it a list of values that can comprise the entire lifecycle of a request/response exchange.

I had the same thought. It's probably best specified as a List of Decimals; see:

But, I also wonder if the response is the best place to put this information -- it only makes it available after the fact, and scatters information that needs to be aggregated for many use cases. More discussion / description of the use cases would help guide the design.

E.g., if the client is an API consumer and their use case is informing their request patterns, it's likely better to get this sort of hint from a description (e.g., OpenAPI) rather than in responses. 

That doesn't mean you shouldn't define the header, of course -- just that it might not be useful on its own. Also, adding headers to responses does ever-so-slightly increase carbon emissions...


Mark Nottingham

Received on Tuesday, 11 April 2023 14:16:38 UTC