Consider HEAD as part of protocol requirements

[azaroth42]

@mejackreed on Slack:
As a Presentation API harvester, it might be good to know up front with a HEAD request what the headers for a response might be. Could there be a SHOULD guidance that Presentation API providers respond to HEAD requests? https://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.4

(Same applies to info.json, but putting it in Prezi milestone)

[azaroth42]

@mejackreed Should this apply to HEAD on image requests as well?

[mejackreed]

I hadn't thought of that, but it seems like it makes sense to be generally available for image requests.

[jpstroop]

Maybe make explicit in Section 6 of Prezi 3?

[azaroth42]

Summary from community call of 2018-08-01: General agreement to put this into the spec, in section 6 of Prezi and equivalent in Image.

[zimeon]

Add to end of section 6 prezi something along the lines of "It is RECOMMENDED that implementations also support HTTP HEAD requests.", a bit more involved in Image API but perhaps add intro to Section 7 which suggests HEAD as well as GET (and OPTIONS)

[zimeon]

Approved by TRC, already merged into image-prezi-rc2.