Scope of semantics

[mnot]

The initial draft suggests 'Preliminary Request Denied', which is fairly specific. In subsequent discussion, a broader semantic, such as 'Purpose Declined' was suggested.

[LPardue]

My 2c:

Maybe its just me but I really struggle with the word preliminary. The draft since conception has had to define what a "premilinary request" is and the only thing it used to do so was to tie it to Sec-Purpose via A preliminary request is one that contains a Sec-Purpose header field [FETCH] with the value "prefetch"..

While the term preliminary is general, if its tied so closely only to Sec-Purpose: prefetch, the scope remains the same. Is the issue here about the shaking out whether we want to support request of other similar nature?

Part of what I struggled with is that the word preliminary implies the thing wasn't full, final, or conclusive. My undersstanding is that a prefetch is not an attempt to get a partial or minimal view of a resource, its an attempt by a client to get the thing and use it at a time, for a purpose it believes is "good" but the server disagrees at that moment.

One reason a server might reject a prefetch or preload is because its too early in the timeline. Sad that we already have 425 Too Early for an entirely different case 😄

I recall a little while back talking to folks about Fetch metadata, expanding scope to accomodate those things seems like expanding the scope too far.

[martinthomson]

One reason to deny a prefetch is that the serving of the content might have side-effects (consider the display of ads as an example, which often involves payment or at least the recording of an impression). So the use case is fine. And 400 series is right.

The question about scope is the hard one. "Purpose Declined" is a reasonable thing to expand it to, though it might not be expanding it at all unless there are other purposes that are eventually defined.

I wonder whether this couldn't be expanded to include Sec-Fetch-Dest as well, perhaps even Sec-Fetch-Mode. The idea here is that the context into which the response will be placed is not compatible with the expectations of the server.