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Re: My thoughts on the multi-body alternatives (as shown on Tim's wiki page)

From: Doug Schepers <schepers@w3.org>
Date: Wed, 19 Aug 2015 00:06:06 -0400
To: Robert Sanderson <azaroth42@gmail.com>
Cc: t-cole3 <t-cole3@illinois.edu>, Ivan Herman <ivan@w3.org>, W3C Public Annotation List <public-annotation@w3.org>
Message-ID: <55D400AE.5020608@w3.org>
Hi, Rob–

I'm glad we seem to be converging on some sort of agreement. I hope 
others feel the same.


I'd like to be explicit about one more related thing from the spec; as 
we've tossed around these examples, I don't know if there was an 
understanding about "EmbeddedContent" that was elided.

Currently, the spec says [1]:

[[
If the requirements for a simple textual Body are not met, and the 
representation of the Body is to be embedded within the Annotation's 
serialization, then the Body MUST be a resource and MUST have the class 
oa:EmbeddedContent. The content of the Body is recorded as the value of 
the rdf:value property, and additional properties such as dc:format and 
dc:language SHOULD be given if known.
]]

And here are some examples from the spec:

   "body": {
     "@type" : "oa:EmbeddedContent",
     "value" : "content",
     "format" : "text/plain",
     "language" : "en"
   }


   "body": {
     "@type": [ "oa:Tag", "oa:EmbeddedContent" ],
     "value": "paris"
   }

Does the "type":"EmbeddedContent" really need to be explicit? Or can it 
be inferred and left out? I guess the same question goes for 
"SpecificResource".


In general, I'd like to trim out everything that can be trimmed out 
while still making sense.


As another example of this, if we have a selector defined in the data 
model, do we really need to include the "conformsTo" property in a 
Selector object? Or is that something that is only defined in the 
@context, or better yet, in the spec? Is there such a thing as "implied" 
properties (like defaults) in JSON-LD/RDF?


I'd like for us to clearly define what properties each type of object 
requires, which are allowed, and which (if any) are implied.

[1] http://www.w3.org/TR/annotation-model/#embedded-textual-body

Regards–
–Doug


On 8/18/15 8:06 PM, Robert Sanderson wrote:
>
> On Tue, Aug 18, 2015 at 4:26 PM, Doug Schepers <schepers@w3.org
> <mailto:schepers@w3.org>> wrote:
>
>     1) We allow (but don't require) an "id" property on each object, to
>     make it addressable;
>
>
> +1. This isn't a change, and we can't require that resources do not have
> identity, so I don't see that there's any other option.
>
>     2) We strive for a single consistent structure that applies equally
>     to Body, Target, Tag, and so on, modulo the proposal in #3.
>
>
> +1. One simple way for everything is better than two simple ways, but
> one simple way for some things and one complex way for the minority of
> cases is better than one complex way for everything that then doesn't
> get used.
>
>     3) We make the nested "source" object a SHOULD, while the empty-node
>     construct is only a MAY, and only allowed for text-literal
>     resources, and (maybe?) only in a non-Linked Data context; we define
>     a clear equivalence mapping.
>
>
> Sure. +0.9
>
> Sub proposals:
>
> 3.1) I'd go further to be explicit that the nesting is for consistency
> to make developers' lives easier.  [one way > two ways, per 2]
>
> 3.2) We could also define a subClass of
> the-class-currently-known-as-EmbeddedContent for Bodies that allows
> roles to be associated with it, which would make it clear that embedded
> stylesheets do not get roles.  In the JSON, they could then have
> different type property values for clarity, if needed.  [Be explicit and
> rigorous in the model, hide the details from developers unless needed]
>
> 3.3) We should explicitly state that systems MAY translate between
> equivalent structures as desired, similar to the ability to translate
> from a literal body to a body as a resource... so even though you sent
> in one form, the receiving system may process it into another form.
>
> Essentially the "Role Attached to SpecificResource or EmbeddedContent"
> option, with a preference for using SpecificResource.
>
>
>     4) We define the default type of "value" to be "text". We require
>     explicit "type" values for all other datatypes.
>
>
> If there was a new EmbeddedTextualBody class per 3.2, it wouldn't be
> necessary to have a default.  Systems could infer that specific class
> for bodies that have a value property.
>
> 4.1) If we wanted to be very explicit, we could define our own property
> just for this that wasn't "value".
>
> {
>   "body": {
>      "role": "tagging",
>      "content": { "text" : "+1" }
>    }
> }
>
> As opposed to value for things that aren't embedded representations of
> resources, such as in FragmentSelector:
>
> "body" : {
>      "role": "commenting",
>      "selector": {"type": "FragmentSelector", "value": "xywh=0,0,100,100"},
>      "content": "http://some.url/image.jpg"
> }
> Reuse when it makes sense ... and maybe it doesn't make sense here. The
> original ContentAsText spec invented two such properties (bytes and
> chars) so we would still be improving the situation!
>
> So I'm +0 on 4 ... because I think it's unnecessary given 3.2 and 4.1?
> But let us know what you think.
>
>
>     5) We continue to discuss property names that might be more
>     intuitive. For example, I find "source" less clear than "content",
>     and I'd like to see different proposals for the terms
>     "EmbeddedContent" and "SpecificResource".
>
>
> Sure. Naming, as opposed to correct structure and semantics, is the
> least of my concerns :)  You can call it a
> F5D28594-021D-426A-B169-A1E8167D5BA6 if you want :) [As editor, I'd
> prefer you didn't tho!] The advantage of JSON-LD is that others who
> really prefer a different name can still call it whatever they want too,
> by defining a different context for the same properties and relationships.
>
> Thank you very much for the concrete proposal Doug, it's greatly
> appreciated, and I hope that the above agreement is encouraging to everyone.
>
> Rob
>
> --
> Rob Sanderson
> Information Standards Advocate
> Digital Library Systems and Services
> Stanford, CA 94305
Received on Wednesday, 19 August 2015 04:06:11 UTC

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