Re: Bodies resource from Benjamin

Okay, as this has not been discussed previously, we should give it a fair

Riffing on the strawperson from Benjamin and the mention of Composites from
Jacob, today I have been trying to model the requirements we have in the
following way:

The body or target of an annotation is a Composite, where that resource has
relationships to the included resources.  Those relationships would replace
the use of motivations, and the base set would be enumerated in the model.
Additional relationships could be created to cover further use cases, such
as the copy-edit replacement or the canvas-painting motivation in IIIF.

This would NOT suffer from the main objection to using subProperties of
hasBody/hasTarget, which is that it would be impossible to determine which
resources were bodies, which were targets and which neither, as
hasBody/hasTarget would point to the Composite.  As the Composite is a
construction within the Annotation, there would be no need to have
properties other than motivation replacing relationships, thus a pure
JSON/javascript client could iterate through all of the properties
(excluding id and type) and know that they were bodies (or targets) even if
they do not understand the semantics.  For annotations with a known
structure, the direct method of accessing the information would work
(anno.body.replacement) meeting the performance requirements expressed.

For example:

  "@context": [
  "id": "",
  "type": "Annotation",
  "target": {
  "resource": ""  // should really be a
SpecificResource with Selector
  "body": {
     "type": "Composite",
     "tags": [ {"text": "correction"}, {"text": "typo"} ],
     "comments": {"text": "wow...I should learn to type..."},
     "replacements": {"text": "itinerary"}

Here resource is oa:item (which we could rename), and tags, comments,
replacements are all subProperties of it.  Replacements is defined in the
second context.

However, don't get too excited ... this does NOT work with the other
multiplicity constructions where the order of the members is important.
Although in JSON, the value of "tags" is an array, that is actually the
following turtle:

_:body a oa:Composite ;
  oa:hasTag [ oa:text "correction"], [ oa:text "typo"]

And not an rdf:List:

_:body a oa:Composite ;
  oa:hasTag ( [oa:text "correction"] [oa:text "typo"])

(Apologies to those who do not speak turtle as a native language -- the
first is not ordered, the second is)

Thus, a Choice of comments could NOT be modeled as:

"body": {
  "type": "Choice",
  "comments": ["", "" ]

Because this would require comments / oa:hasComment to be both ordered in
some instances and not ordered in others, which is not possible.

Two separate keys and predicates that reflect the same motivation could be
created (commentsList / oa:hasCommentList, comments / oa:hasComment) but
that seems pretty terrible, especially as the values for the two would be

The current proposal does allow for this use case, as the Composite or
Choice would simply have SpecificResources with motivations as

Unless someone else can see how this could work (in RDF and JSON please),
while fulfilling all of the requirements?


On Tue, Sep 1, 2015 at 10:06 AM, Doug Schepers <> wrote:

> Hi, Benjamin–
> I realize that you were probably just putting out a strawman for
> discussion, and that you were probably making a different point, but since
> you are talking in code, I thought it would be useful to make a specific
> point about your code.
> Just a high-level response, inline…
> On 9/1/15 11:40 AM, Benjamin Young wrote:
>> On Tue, Sep 1, 2015 at 11:21 AM, Robert Sandersonwrote:
>>         Where this is trending now in my head is that we *keep*
>>         motivation on the annotation, but create classes for bodies.
>>         What this *might* look like in JSON-LD is something like:
>>         ```
>>         {
>>            "type": "Annotation"
>>            "motivation": "editing",
>>            "bodies": {
>>              "tags": ["correction", "typo"],
>>              "comment": "wow...I should learn to type...",
>>              "edit": {
>>                "original": "itinirary",
>>                "replacement": "itinerary"
>>              },
> This should not be necessary, under any of the proposals we'd been
> considering thus far.
> My immediate reaction was (I think) similar to Rob's:
>     * A pattern for extension that doesn't involve subProperties is what
>>     we have now.
> If I'm reading Rob correctly, this means that none of the bodies (or
> targets) should have special sub-properties (or sub-structures) of the same
> type (e.g. motives/motivations/roles) that require special parsing or
> processing.
> (Note that Target does have Selectors each with idiosyncratic properties,
> but in this case, I think it's unavoidable and they are clearly defined.)
> Without making any judgment for or against other aspects of your strawman,
> and keeping everything else the same to isolate this single point for
> discussion, here's how I'd reformulate your strawman:
>  ```
>  {
>     "type": "Annotation"
>     "motivation": "editing",
>     "bodies": {
>       "tags": ["correction", "typo"],
>       "comment": "wow...I should learn to type...",
>       "edit": "itinerary",
>       "related": [""]
>     },
>     "target": ""
>     "target": {
>       "source": "",
>       "selector": {
>         "type": "oa:TextQuoteSelector",
>         "exact": "itinirary"
>       }
>     }
>  }
>  ```
> Yes, it's slightly longer. But has the same functionality, and it avoids
> two crucial problems:
> 1) the needless duplication of information;
> 1a) you'd need a TextQuoteSelector in the target anyway to correctly
> anchor the selection;
> 1b) mechanisms that duplicate information in multiple places are prone to
> getting out of sync and causing problems;
> 2) the need for idiosyncratic and potentially unpredictable additional
> structures or properties within a known type of property
> 2a) this makes processing more difficult even for known structures of this
> type
> 2b) introducing such a structure into an extension point sets a pattern
> that makes graceful degradation very difficult
> And, again, it's not necessary. I think it's useful for use to talk about
> these edge cases (and central use cases) because it helps us validate that
> our design is practical and versatile. In this case, you wrote some
> strawman code that might well have been done by a developer unfamiliar with
> the data model's design principles, and we were easily able to reformulate
> it into something that easily avoids the problems.
> This tells me 2 things:
> 1) the data model is strong and flexible;
> 2) we need to be really clear about how the model works, in terms the
> average developer can understand, and show explicitly how to add extensions
> (where they can be added, and how they should be structured); we can
> provide examples to make it clearer (like Rob's  “antecedent” and
> “subsequent” motives).
> On a related topic (which I'm putting here just to capture it)…
> Note that this my formulation has a somewhat interesting side effect.
> Since the TextQuoteSelector doesn't have a "prefix" or "suffix", it's
> ambiguous which instance of the "exact" quote value "itinirary" it's
> referring to, if there was more than one misspelling in the same document.
> Is it the first instance? The last instance? All instances? Is this a hack
> for spellcheck, or an abuse of the data model? Should this be expressed as
> multiple targets? Or should we define some "all instances" property? Or
> should we require a "prefix" and/or "suffix"? Is the Data Model the right
> place to define UA behavior for resolving selectors? Or should there be
> another spec, perhaps something that defines UA behavior for selectors in
> terms of RangeFinder and other APIs?
> Food for thought.
> Regards–
> –Doug

Rob Sanderson
Information Standards Advocate
Digital Library Systems and Services
Stanford, CA 94305

Received on Wednesday, 2 September 2015 03:21:06 UTC