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Re: [web-annotation] HTML Serialization Use Cases

From: Ivan Herman via GitHub <sysbot+gh@w3.org>
Date: Fri, 08 Apr 2016 17:55:41 +0000
To: public-annotation@w3.org
Message-ID: <issue_comment.created-207536969-1460138139-sysbot+gh@w3.org>
Looking at the 
[comment](https://github.com/w3c/web-annotation/issues/147#issuecomment-207198440)
 put in by @tcole3 :

First of all, what I like in all these approaches is that they work 
out of the box today, without any need for an extension of HTML. That 
is a major plus. However I believe that, for practical purposes, we 
could cross microdata from the list. Microdata, as far as I know, is 
used only by schema.org (which is of course important!); I do not know
 of any other environments, tools, etc, that would process microdata.

One of the main complications (maybe _the_ major complication) of the 
RDFa encoding is that, being a true RDF serialization, it relies on a 
number of namespaces (duly set in a `@prefix` attribute). RDF 
experts/users have no problem with that, it is in their blood :-), but
 the Web Application community frowns on that (nay, they vehemently 
refuse doing that). We have avoided this problem in JSON-LD with the 
help of the appropriate `@context` file but, alas!, nothing like that 
exists in RDFa.

*If* we expect the RDFa encoding ever being done by human users and 
not only by machines behind the scenes, we may have to address this. 
There is an approach to do that, but I have to ask my RDF friends to 
hold their nose:-): we can define a single namespace vocabulary that 
consists of nothing else than a series of `owl:sameAs` statements (or 
equivalents for classes and properties) to the resources in the OA 
Vocabulary. Ie, it would provide, essentially, aliases (via 
`owl:sameAs`) to `oa` terms, `dc` terms, etc. A fake `@context` file, 
thus. If we do this, we can greatly simplify the RDFa encoding:

```
<p vocab="http://my.fake.vocabulary.ns">On August 1, 1779, F...
                from the <span id="Anno1" typeOf="Annotation" 
resource="http://w3c.github.io/web-annotation/htmlSerialization/BlogEntryAnnotatedRDFa.html#Anno1">
                        <time property="created" datatype="dateTime" 
datetime="2015-01-28T12:00:00Z"></time>
                        <span property="creator" 
resource="http://www.library.illinois.edu/people/bios/t-cole3/" 
typeOf="Person"><meta property="name" content="Tim Cole"/></span>
                        ...
```

etc.

It *is* an ugly hack from an RDF point of view, although perfectly 
"legal". But it works, and may become then a fairly acceptable way of 
encoding an annotation in RDFa.

Take a deep breath before you answer:-)


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