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RE: An updated draft of the schema.org/Action proposal

From: Markus Lanthaler <markus.lanthaler@gmx.net>
Date: Tue, 28 Jan 2014 15:22:47 +0100
To: "'Sam Goto'" <goto@google.com>
Cc: "'W3C Web Schemas Task Force'" <public-vocabs@w3.org>, <public-hydra@w3.org>
Message-ID: <01b001cf1c34$6d4c7c80$47e57580$@lanthaler@gmx.net>
On Tuesday, January 28, 2014 6:02 AM, Sam Goto wrote:
>
> Here is another challenge with this approach: how do you set up the
> expectations on the properties of the Action class? That is, most of
> the invocations take more than one parameter and they map to one of
> the Action properties (e.g. RsvpAction takes an "agent" as well as an
> "attendance" -- whether the agent is going or not).

It depends. If the agent, e.g., is fixed as it is in most cases when you send an invitation by email I would encode it in the URL the response is sent to. If it isn't, I would create an RsvpResponse class defining those two properties as you do below.


> If you had to declare that as a SupportedClass, that would require the
> handler to take a SupportedClass that is subClassOf a RsvpAction,
> which is a lot verbose [1].

It always depends a lot on how you format these things. If the range of something is clear, there's also no need to specify it explicitly. Thus, [1] could be written as

{
  "@context": "http://schema.org",
  "@type": "Event",
  "@id": "http://code.sgo.to/events/123",
  "name": "Taco Night",
  "startDate": "2015-04-18T15:30:00Z",
  "endDate": "2015-04-18T16:30:00Z",
  "operation": {
    "@type": "RsvpAction",
    "expects": {
      supportedProperty: [
        { "property": "rsvpAttendance" },
        { "property": "http://schema.org/agent",
           "rangeIncludes": {
             "subClassOf": "Person",
             "supportedProperty": { "property": "name" }
           }
        }
      ]
    }
  }
}

Which I don't find that verbose


> Option [2] is an attempt to cut down a bit the verbosity by allowing
> the "expects" property to take "Property", "SupportedProperty" (which
> refers to the Action-level properties) as well as "SupportedClass".

I still have troubles seeing how an application without further knowledge will be able to tell whether "http://schema.org/rsvpAttendance" in that example is a Property or a SupportedProperty. It would have to go and dereference that URL to look up its definition to find that out.

 
> Option [3] is what gmail lanched with, which, apart from strict
> preciseness, it is quite concise and clean.

Yeah, it is concise and clean but the "agent.name" string doesn't mean anything without out of band knowledge. For me, that's a deal breaker. It works for something like Gmail because Google is big and important enough to enforce these things but looking at the bigger, decentralized Web it won't work at all IMHO.


> Markus, have you run into problems describing nested objects on
> "expects" (e.g. a bug needs an author which in turn needs to have at a
> minimum an id?)?

Yeah, I have been thinking about this but wasn't able to find an elegant solution yet. If you start relying on Linked Data principles, i.e., dereferenceable URLs to look up definitions (of course all concepts can be defined in a single document) a lot of these deeply nested structures go away as you simply reference the various concepts. In many other cases, it is possible to eliminate the nesting by creating a new specialized type or by encoding some of the information in the URL the data is sent to.


> [1]
> 
> {
>   "@context": "http://schema.org",
>   "@type": "Event",
>   "@id": "http://code.sgo.to/events/123",
>   "name": "Taco Night",
>   "startDate": "2015-04-18T15:30:00Z",
>   "endDate": "2015-04-18T16:30:00Z",
>   "operation": {
>     "@type": "RsvpAction",
>     "expects": {
>         "@type": "SupportedClass",
>         "subClassOf": "http://schema.org/RsvpAction",
>         supportedProperty: [
>           {"@type": "SupportedProperty",
>           "property": "http://schema.org/rsvpAttendance"}
>           {
>             "@type": "SupportedProperty",
>              "property": "http://schema.org/agent",
>              "rangeIncludes": {
>                "@type": "SupportedClass",
>                "subClassOf": "Person",
>                "supportedProperty": [
>                   {"@type": "SupportedProperty",
>                    "property": "http://schema.org/name"}
>               ]
>           }
>       ]
>     }
> }
> 
> [2]
> 
> {
>   "@context": "http://schema.org",
>   "@type": "Event",
>   "@id": "http://code.sgo.to/events/123",
>   "name": "Taco Night",
>   "startDate": "2015-04-18T15:30:00Z",
>   "endDate": "2015-04-18T16:30:00Z",
>   "operation": {
>     "@type": "RsvpAction",
>     "expects": [
>        // this is a property that refers to the top level action
>       "http://schema.org/rsvpAttendance" 
>        {
>             "@type": "SupportedProperty",
>              "property": "http://schema.org/agent",
>              "rangeIncludes": {
>                "@type": "SupportedClass",
>                "subClassOf": "Person",
>                "supportedProperty": [
>                  "http://schema.org/name"
>               ]
>           }
>       ]
>     }
> }
> 
> [3]
> 
> {
>   "@context": "http://schema.org",
>   "@type": "Event",
>   "@id": "http://code.sgo.to/events/123",
>   "name": "Taco Night",
>   "startDate": "2015-04-18T15:30:00Z",
>   "endDate": "2015-04-18T16:30:00Z",
>   "operation": {
>     "@type": "RsvpAction",
>     "optionalProperty": [
>       // this is a property that refers to the top level action
>       "rsvpAttendance"
>       // this is a property that refers to the agent name
>       "agent.name"
>       ]
>     }
> }



--
Markus Lanthaler
@markuslanthaler
Received on Tuesday, 28 January 2014 14:23:19 UTC

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