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Re: [web-annotation] Multiplicity and Collections

From: Rob Sanderson via GitHub <sysbot+gh@w3.org>
Date: Tue, 12 Jan 2016 19:57:56 +0000
To: public-annotation@w3.org
Message-ID: <issue_comment.created-171035575-1452628674-sysbot+gh@w3.org>
I think the analysis comes out very good :)
Given the recently updated AS: 
https://www.w3.org/TR/activitystreams-core/#collections and the 
current multiplicity constructs, the mapping is very easy:
  * Choice becomes a subClassOf OrderedCollection
  * List is replaced by OrderedCollection
  * Drop Composite as unnecessary and either overly complex or out of 
scope

We have to specify OrderedCollection and paging for the protocol. In 
order to do that we have to have them referenced from the model. 
Following our principles, we should not invent something new when 
there's an existing term, and we should have only one way to do 
something.  Currently there are multiple ways to create an ordered 
list.

So the cost to the model is free to merge them, and non-free to have 
both.

In terms of implementation, I know of several implementations of 
Choice. The Protocol will provide implementations of 
List/OrderedCollection, and the IDPF have an explicit requirement for 
it. In the model, the only distinction needed (if we accept #93 to 
cover execution order) at the Annotation level is whether the targets 
or bodies are:
  * separate individuals (by way of multiple hasTarget/hasBody rels)
  * all required together (by way of as:OrderedCollection)
  * or whether any one of them is required (by way of oa:Choice)

I would actually be okay to drop the second bullet and Composite/List 
completely, given #93.  I don't think we'll get 2 independent 
implementations that do anything meaningful to exit CR, so we could 
just drop them now and leave it up to other 
standards/ontologies/systems to determine.

To respond to @jjett:
  * I disagree that there is any implication that a consuming software
 agent will combine resources in a Composite in any way that they 
might not also do for a List.
  * An unordered set of pages is not a book, which has order.  A Book 
is at least better represented as a List, if not a more complex 
structure.  Also, we're not providing a Book structure ontology!
  * There's no reason why a collage or a collection should NOT have an
 order: there's no additional cost given that the serialization will 
imply an order anyway. In some situations (z-axis ordering, relevance,
 etc) it may even be essential.  
  * We should avoid epistemological debates about identity. Whether a 
collection exists outside of the Annotation ontology is entirely 
irrelevant to an Annotation discussion.  Other ontologies can describe
 those things, and the entities can be annotated.  The use cases for 
including them in the Annotation Ontology must be directly related to 
the Annotation, not complex descriptions of the target.  The ordered 
presentational or execution framework is _exactly_ what we need in 
this context.





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Received on Tuesday, 12 January 2016 19:58:04 UTC

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