ISSUE-4: Should the registry allow a property name or URI to be used as an alias for @itemid

Property as subject

Should the registry allow a property name or URI to be used as an alias for @itemid

State:

CLOSED

Product:

Microdata to RDF

Raised by:

Gregg Kellogg

Opened on:

2011-11-05

Description:

Schema.org provides a 'url' property which, in practice, is used to set the subject for an item. Moreover, in many examples, the property is used with a literal content model, rather than a URI content model.

For example, the following use case is common in schema.org examples:


<div itemprop="tracks" itemscope itemtype="http://schema.org/MusicRecording">
<span itemprop="name">Rope</span>
<meta itemprop="url" content="foo-fighters-rope.html">
...
</div>

In this case the @content attribute is used where the value is expected to be a URI. And, it is clear that this URI is intended as the subject of the item.

A registry entry could be created which would affect processing of a microdata processor by specifying a content model for the property (URI reference) and that it is to be used as the subject of an item. Note, that there is a special case where the item already has an @itemid attribute, or there are more than one 'url' property values. This could be resolved by using the first property value only if the item has no @itemid.

The suggested behavior would be to use the first 'url' property value both as the item subject and as a property and subsequent values as a property only.

For example, the previous microdata would produce the following Turtle:

<foo-fighers-rope.html> a schema:MusicRecording;
schema:name "Rope";
schema:url <foo-fighters-rope.html> .

A possible JSON representation of a registry that identifies this could be the following:

{
"http://schema.org/": {
"propertyURI": "vocabulary",
"multipleValues": "unordered",
"@context": {
"url": { "@datatype": ["@subject", "@uri"]},
"dateCreated": {"@datatype": "http://www.w3.org/2001/XMLSchema#date"},
...
}
}
}

This notation borrows some concepts from the JSON-LD context, but it is intended for discussion and is not proposed as a repository syntax. As the range is described, any use of this property would treat the value as a URI reference. As a by-product, this can be used for URIs (or IRIs) which are not URLs.

The 'url' refers to http://schema.org/url, and is defined both as having a URI reference data range, and to be used as an alias for the item subject. In contrast, http://schema.org/dateCreated is defined as having an xsd:date range, which would cause the resulting literal to have the associated datatype.

Related Actions Items:

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Related emails:

1. Re: htmldata-ISSUE-4 (Property as subject): Should the registry allow a property name or URI to be used as an alias for @itemid [Microdata to RDF] (from jeni@jenitennison.com on 2011-11-07)
2. Re: htmldata-ISSUE-4 (Property as subject): Should the registry allow a property name or URI to be used as an alias for @itemid [Microdata to RDF] (from ivan@w3.org on 2011-11-07)
3. Re: htmldata-ISSUE-4 (Property as subject): Should the registry allow a property name or URI to be used as an alias for @itemid [Microdata to RDF] (from gregg@kellogg-assoc.com on 2011-11-06)
4. Re: @itemid and URL properties in schema.org (from gregg@kellogg-assoc.com on 2011-11-06)
5. Re: @itemid and URL properties in schema.org (from pmika@yahoo-inc.com on 2011-11-06)
6. Re: htmldata-ISSUE-4 (Property as subject): Should the registry allow a property name or URI to be used as an alias for @itemid [Microdata to RDF] (from ivan@w3.org on 2011-11-06)
7. Re: @itemid and URL properties in schema.org (from gregg@kellogg-assoc.com on 2011-11-05)
8. htmldata-ISSUE-4 (Property as subject): Should the registry allow a property name or URI to be used as an alias for @itemid [Microdata to RDF] (from sysbot+tracker@w3.org on 2011-11-05)

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