Add link type(s) for UI(s)

[mmccool]

See map use case. Edit: also possibly relevant to Accessibility.

[relu91]

Alternate link type might help here. Example:

{
    "@context": [ "https://www.w3.org/2019/wot/td/v1"],
    "links": [{
        "rel": "alternate",
        "href": "https://servient.example.com/things/lampUI",
        "type": "application/html"
     }]
    ...
}

[egekorkan]

Not sure if this word is semantically correct, I would expect an alternative to the TD, like one for a local network served by a proxy/gateway. At the same time, I don't know of a perfect one since the link relation types are "created" for HTML documents that already are the user interface. I think about can be used by adding another keyword with it which can mean the UI is about the TD/Thing.

[mmccool]

Should discuss link types here and make PRs against https://github.com/w3c/wot-architecture/blob/master/REQUIREMENTS/link-relation-types.md to capture them.

[relu91]

Not sure if this word is semantically correct, I would expect an alternative to the TD, like one for a local network served by a proxy/gateway. At the same time, I don't know of a perfect one since the link relation types are "created" for HTML documents that already are the user interface. I think about can be used by adding another keyword with it which can mean the UI is about the TD/Thing.

Agree it is not a super fit. However, the alternate type can be used as a means to convey another representation for a web resource. If we think about a web Thing, it might be described with a Thing Description or an HTML document. Now, since the web is evolved a lot an HTML document is essentially a full-blown UI and I agree that it might be strange to say it is just another way to describe that Web Thing. Still, IMHO people might still use the alternate tag to convey a UI for one WebThing.

However, UI is not only HTML. What about a phone application? we could have a link to that as well. We can:

• define a totally new set of rel types that can work with both HTML and mobile applications. Consequently, recommend those tags instead of alternate tag
• Integrate with the alternate tag and add a specific tag only for mobile applications.

[mmccool]

We should in general, if possible, try to use existing IANA link relation types if they are appropriate, otherwise we should define new ones. Existing IANA types are documented here: https://www.iana.org/assignments/link-relations/link-relations.xhtml
Probably what we should do is state explicitly in the TD spec the use of particular link types for particular purposes. Also as noted above there is a document set up in the wot-usecases repo collecting use cases (and proposed link types) for various purposes. We should probably first try to consolidate suggested link types here: https://github.com/w3c/wot-architecture/blob/master/REQUIREMENTS/link-relation-types.md

[mmccool]

Note also the cross-linked issue in architecture above.

[benfrancis]

I only just spotted this issue as it's in the wot-testing repo. Could be added to the Thing Description specification as a recommended way for a web thing to provide its own web UI? The example @relu91 gave is exactly what WebThings currently does.

See the example in https://webthings.io/api/#links-member

...
  {
    "rel": "alternate",
    "mediaType": "text/html",
    "href": "/things/lamp"
  }
...

By my understanding of the alternate link relation, this is exactly what it's intended for as it is linking from a JSON representation of a web thing to an alternate HTML representation. This is equivalent to an HTML document linking to an alternate RSS representation of the same resource for example.