RESUMABLE: Clarification on `min-size`

[GrantGryczan]

@Acconut wrote the following in #3408 (comment):

The purpose of min-size is mainly to let the client know that the server won't offer resumable uploads for representations outside of those boundaries. But this doesn't mean the representation will be rejected when uploading via a traditional POST request, for example. A server may decide to only use resumable uploads for larger files as there is a cost of holding state involved for upload resources.

And the following in #3408 (comment):

The definitions of max-size and min-size state that the server might not create an upload resource if the indicated representation size falls outside of these boundaries:

...

It doesn't say that upload creation requests with sizes outside of these limits must be rejected. The server can still process the included representation without involving resumable uploads, which is a feature IMO, but a bug :)

I didn't know this! If this is true, this seems important to clarify in the draft. Right now, the definition of min-size also says that it is "a minimum size for the representation data", which is a stronger requirement that I thought disallowed this.

I'd argue having an uncommunicated, separate (or a lack of a) limit for non-resumable uploads is pointless, because a server could just use min-append-size to ensure the entire upload is done in one request under a certain size. The server could even loosen the min-append-size limit after the first request if it only needs that restriction for the purpose of avoiding creating an upload resource. In my opinion, using min-size for this is redundant and may make min-size less reliable for the purpose of restricting the representation data size.

EDIT: Struck through most of my previous argument because I realize min-append-size can't be used to restrict upload resource creation, since it doesn't apply to empty upload creation requests. Is there any common situation where a server would want an actual, final minimum restriction on the total size of an upload, resumable or not? I guess I can't really think of anything.

Lastly, I also wanted to ask for clarification on whether min-size can be enforced by servers during upload append requests rather than during upload creation, since I'm not sure whether a previous comment hinted that it might only be enforced on upload creation. The current phrasing as "a minimum size for the representation data", as opposed to a minimum upload length to allow upload resource creation, makes it seem like it would always be enforced.

[Acconut]

Is there any common situation where a server would want an actual, final minimum restriction on the total size of an upload, resumable or not? I guess I can't really think of anything.

I can't think generic reason either. That's why min-size is intended to indicate what the minimum size is to start a resumable uploads. Server might not want to pay the cost of resumable uploads for representations below that limit, while still accepting and processing these representations when they are uploaded without resumablity using traditional uploads.

Lastly, I also wanted to ask for clarification on whether min-size can be enforced by servers during upload append requests rather than during upload creation, since I'm not sure whether a previous comment hinted that it might only be enforced on upload creation. The current phrasing as "a minimum size for the representation data", as opposed to a minimum upload length to allow upload resource creation, makes it seem like it would always be enforced.

At the end of the day, the server has ultimate control over how/if the uploaded representation is processed. It can stop the upload at any time and discard data as it wants, regardless of what we say the spec. If you want to check the representation's size once the upload's done, that fine as well. min-size isn't a requirement on the server when to assert the limit, but a hint to the client that resumability is likely not available if the representation is below this limit. The client can then decide to use a traditional upload method or stop entirely.

[GrantGryczan]

Fair enough! Thanks for the clarification. In that case, can we change and/or add some phrasing to communicate this? This makes sense but wasn't at all clear from the draft IMO. I'm going to want to change some code around in my client implementation to fall back to non-resumable uploads when under the min-size. Or perhaps I should do the whole upload in a single Upload-Complete: ?1 request under the min-size?