How should we handle links from an asset to its online access point(s)?

[jeff-zucker]

How should we handle links from an asset to its online access point(s)?

When an Asset is available in two versions which are identical other than format, the are considered in ADMS as instances of dcat:Distribution which can specify a URL and metadata about the URL like its IANA media-type.

:SomeDocument
  a adms:Asset ;
  dcat:distribution
    [ dcat:mediaType "text/html"; dcat:downloadURL <..> ],
    [ dcat:mediaType "application/pdf"; dcat:downloadURL <..> ],

For Assets which have a single version, the dcat:accessURL is available. But its object is a simple URLs which would not allow us to differntiate between different kinds of URLs. For example a mailing list accessURL might be a subscription link or an archive link; a software might have different links to code, the dataset used, or a webapp running the code. And none of those things depend on media type. Further, they do not necessarily represent versions of an identical thing in a different format so can't really be considered dcat:Distributions.

So there is no current term in ADMS/DCAT that I know of that would handle multiple typed links for an asset where the links do not point to different versions of the same thing like a distribution. I propose we use typed links where the types are stored in the concept scheme. Something like this:

@prefx t: <./solid-skos-concept-scheme.ttl> .

:CG_Mailinglist vcard:url
  [ dct:type t:Subscription ;   vcard:value <...>; ] ,
  [ dct:type t:Archive ;        vcard:value <...> ].

:Solid_Catalog vcard:url
  [ dct:type t:Webapp ;         vcard:value <...>; ] ,
  [ dct:type t:Dataset ;        vcard:value <...>; ] ,
  [ dct:type t:CodeRepository ; vcard:value <...> ].

This is similar to the solution which SolidOS uses by adding 'WebId' to the vcard ontology so that we can say things like

:me vcard:url [dct:type vcard:WebId; vcard:value :me].

However, by allowing the object to be a SKOS concept rather than a class in an external ontology, we stay in sync with the skos structure used to type assets and we can create the types in a structured way.

[elf-pavlik]

To follow up on #16 (comment)

<#OrganizationA> vcard:url 
   [ a vcard:HomePage; vcard:value <homepage-uri> ],
   [ a vcard:WebID; vcard:value <webid-uri> ],

In what way this qualified relations approach is preferable over using direct relation and existing properties and classes this way:

<#OrganizationA>
  foaf:homepage <https://a.example> ;
  foaf:isPrimaryTopicOf <> .

<https://a.example> a schema:WebPage .
<> a foaf:PersonalProfileDocument .

Or from snippet from the original comment here

:Solid_Catalog vcard:url
  [ dct:type t:Webapp ;         vcard:value <...>; ] ,
  [ dct:type t:Dataset ;        vcard:value <...>; ] ,
  [ dct:type t:CodeRepository ; vcard:value <...> ].

vs.

:Solid_Catalog
  ex:browserApp <...>;
  ex:repository <...> .

<...> a schema:SoftwareApplication .

<...> a ex:CodeRepository .

<...> a dcat:Dataset ;
  dcat:landingPage :Solid_Catalog .

[jeff-zucker]

In what way this qualified relations approach is preferable over using direct relation and existing properties and classes

It probably isn't in most cases. I've dropped my advocacy for a WebID predicate so its no longer relevant there. What it is relevant to is #24 - the question of "what can I open this thing with". It is often helpful, for example, to know in advance whether a given URI is RDF. I don't have any immediate need for typed links, so was referring back to it mostly in response to @jg's comments. Since this doesn't have much to do with the current deployment, I'd prefer to come back to it if it becomes relevant at a later point and not get into it further now.

[elf-pavlik]

It is often helpful, for example, to know in advance whether a given URI is RDF.

Using ldp:RDFSource is probably too restrictive but just thinking out loud

<https://here.example> ex:coolRelation <https://there.example> .
<https://there.eaxmple> a ldp:RDFSource .

What was the AAA slogan, "Anyone can say Anything about Any topic."?