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On Fri, Nov 17, 2023, 14:47 David Waite <david=
40alkaline-solutions....@dmarc.ietf.org> wrote:

> wMy concern is higher level, that we may be promoting over-expression of
> types.
>
> My interpretation of historical decisions/retconning was that +xml made
> sense because XML documents form an object model that can be processable
> independently of the document.
>
> For the example of SVG data in an XHTML document, without a media type you
> could still understand that the document contained XHTML because of the
> namespaced root element. You could also understand the SVG data even
> without knowledge of XHTML. There is both an expectation that
> application/xml could be interpreted as XHTML by supporting tools, and that
> there was value in generic XML processing even without understanding the
> media type.
>
> Data expressed in the multiple RDF formats are similar to the XML case
> above - for a graph or subgraph, there are defined predicate relationships
> that could be understood outside the given context. An example would be W3C
> verifiable credentials - I can subject relationships in a credential
> without understanding what a verifiable credential is, because existing
> types and predicates may be in use.
>
> For JSON on the other hand, there is no expectation of universal
> consistency - there are only heuristics to attempt to interpret the data
> outside of context.
>
> We use suffixes for a second purpose - to group related media types
> together when they ‘only’ differ by format, e.g. application/calendar+xml
> and application/calendar+json
>
> For multiple suffixes, I might make a case that something like +rdf+xml
> provides value in that even without knowledge of RDF processing, RDF XML is
> still namespaced and there is the possibility of interpreting the contents
> of the document via XML tooling.
>
> I’m not sure +ld+json provides the same value, as there is no name spacing
> or other application/json rule that would provide an interpretation of the
> media as a generic type. The processor of that media would need still need
> context in order to process the data, and if they have the domain knowledge
> necessary to have that context they could just deal with the fully
> expressed media type.
>
> -DW
>
> On Nov 17, 2023, at 11:03 AM, Orie Steele <orie@transmute.industries>
> wrote:
>
> Alexey Melnikov and I had a chat about
> https://datatracker.ietf.org/doc/draft-ietf-mediaman-suffixes
>
> I am sharing a summary of our discussion for the benefit of the list,
> obviously this was just a discussion, and the media types working group
> will need to decide if or how to address any of these topics.
>
> Regarding media type parameters, there should be no automatic inheritance.
>
> There can be parameters that come from the top level, the subtype, the
> first structured suffix, or the last structured suffix.
>
> An interesting parameter to consider would be "profile" which is common.
>
> There should be commentary on media type parameters, especially
> regarding cases where:
>
> application/ld+json and application/json might both have chosen to
> register a common parameter name, such as "charset" or "profile".
>
> +ld+json seems to be fine.
>
> +jwt is confusing, since it's ambiguous which part, the header, payload,
> or signature will be passed along.
>
> The validation rules here, are also problematic, in that they don't
> directly address this case:
>
>
> https://datatracker.ietf.org/doc/html/draft-ietf-mediaman-suffixes-06#section-2.5.1
>
> We think the ambiguity here could be resolved, for JWT or CWT, the payload
> is the natural part that is relevant, and this aligns with the current
> intended use case within W3C.
>
> For example, W3C specs current request registration of:
>
> typ: application/vc+ld+json+sd-jwt
> cty: application/vc+ld+json
>
> Where decoding the payload produces application/vc+ld+json.
>
> We should comment on this explicitly and warn implementers planning to use
> multiple suffixes with:
>
> +jwt
> +cwt
> +sd-jwt
> +jose
> +cose
>
>  ... or future similar structured suffixes...
>
> To do their best to conform to this behavior, or explain why they deviated
> clearly, in their registration request.
>
> An alternative recommendation might be to flatten the suffixes, when
> pairing with envelope content types, for example:
>
> application/vc-ld-json+sd-jwt
>
> This would also reduce unnecessary registrations, and simplify the
> guidance to designated experts regarding subtypes
> with multiple structured suffixes that are each envelope formats (for
> example, +cwt  / +jwt)
>
> When flattening is not an option, we recommend registering all suffixes,
> to ensure consistency, safety checks, and to be explicit over implicit.
>
> For application/vc+ld+json+jwt and application/vc+ld+json+sd-jwt this
> would mean registering:
>
> for application/vc:
>
> - +ld
>
> - +ld+json
>
> - +ld+json+jwt
> - +json+jwt
>
> - +ld+json+sd-jwt
> - +json+sd-jwt
>
> Some of these registrations could be made with a warning, saying, do not
> use at this time.
>
> On the section regarding adjudication of registrations on the same
> subtype, for the case where:
>
> application/vc+ld+json is registered and the change controller is W3C.
>
>
> https://datatracker.ietf.org/doc/html/draft-ietf-mediaman-suffixes-06#section-2.3
>
> We feel that the designated expert should have the ability to overrule the
> change controller, but that their decision should be appealable to IESG.
>
> We should reach out to IESG regarding this proposal in case they have
> comments.
>
> We think the common case will be that the designated expert will consult
> the change controller, and agree with their position,
> in the case the designated expert feels there is some unreasonable
> position being taken by the change controller,
> they should be allowed to overrule the change controller, and that
> decision should be appealable.
> In the case of W3C, this would likely involve working with W3C
> Liaisons and the IAB as well.
>
> In the case of other organizations, it might be helpful to be able to
> consult the IESG on the best course of action.
>
> In the case that the designated expert agrees with the change controller,
> the registrant should seek a non conflicting subtype,
> for example vc2, or a flattened subtype, for example vc-ld-json
>
> We discussed content formats, and we don't think there are any issues with
> that registry, and the approach taken by multiple suffixes.
>
> In summary, I think the main item remaining is the guidance on "skipping
> registrations" or "flattening" or "registering and recommending against
> use".
>
> This was also the last comment on the topic during the session at IETF 118.
>
> My personal preference would be to recommend the following to the group,
> regarding intermediate suffixes:
>
> 1. flatten whenever possible.
> 2. register and recommend against using.
> 3. skip registration and deploy without considering interpretation of
> intermediate suffixes.
>
> Alexey, please correct anything I miscommunicated.
>
> Regards,
>
> OS
>
> --
>
> ORIE STEELE
> Chief Technology Officer
> www.transmute.industries
> <https://transmute.industries/>
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