Re: [dispatch] Fw: Re: Proposal for Per Resource Events Protocol

[Michael Toomim <[e-mail]>]

On 8/8/23 10:37 PM, Rahul Gupta wrote:
>> Why not use a new method rather than overloading GET? For instance
>> SUBSCRIBE is already used in SIP with approximately the semantics you
>> want. Using a separate method would ensure that caches, etc. could
>> treat subscription requests specially; by default, they wouldn't cache
>> them at all.
> GET is simpler as it is the default method for Fetch. There is already a precedent for changing the semantics of GET, for example, with the Range header (RFC9110, section 14.2) which already works well with caching.

This question came up in the design of Braid-HTTP 
<https://datatracker.ietf.org/doc/html/draft-toomim-httpbis-braid-http> 
as well, and we also chose to augment GET with subscription 
semantics—although the decision was controversial—because we want to 
preserve the other existing behavior of GET. The only thing we had to 
solve was the cache issue.

We address caches by returning a different response type: `209 
Subscription` instead of `200 OK`, and adding a `Cache-Control no-cache, 
no-transform` header. Discussion is here 
<https://github.com/braid-org/braid-spec/issues/16>.

MNot also suggested using "non-final" 1xx response codes in 
https://www.mnot.net/blog/2022/02/20/websockets#extending-http, which 
would be quite interesting to explore.