Re: [core] Designs to resolve streaming issues in SenML

[Michael Koster <[e-mail]>]

> On Jan 18, 2016, at 8:58 AM, Christian Amsüss <[e-mail]> wrote:
> 
> Again a short reply before going through the full mail:
> 
> On Mon, Jan 18, 2016 at 08:23:00AM -0800, Michael Koster wrote:
>> {
>> "bn":"/3300/1/",
>> “i":[ {"n":"5700","v":"31.3"} ],
>> "l":[
>>  {"href":"","rel":"self","rt":"temperature core.s","u":"C"},
>>  {"href":"5700","rt":"currentValue","u":"C"}
>> ]
>> }
>> 
>> Base name, links, and items all are easily mapped to property names
>> using a simple JSON-LD context and can be understood and modeled 
>> by higher level tools as-is. Removing the “i” or “l” tags gives the modeling 
>> tool nothing to use to identify property instances (like base name, links, 
>> and items). This is extensible by adding new property  classes (element 
>> tags).
> 
> I'm curious: Is JSON-LD at all able to derive, from the above (I took
> the liberty to abbreviate and add a second rt), statements like
> 
> <http://.../3300/1/> a core:s, some:temperature ;
>    some:self <http://.../3300/1/>; core:unit "C" ;
> <http://.../3300/1/5700> a some:currentValue ;
>    core:grp <http://.../3300/1>;
>    some:value "31.3"
> 
> ? That would require matching the bn and n for URI concatenation and
> whitespace-splitting the rt attribute.
> 
JSON-LD needs JSON document format to start with, so I first transform 
link-format to link-format+json which makes multi-valued attributes an array. 

The tags are mapped to property names in the JSON-LD context using maps
like in this example context for my W3C WoT schema. 

"capabilities": {"@id": "ts:hasCapability", "@type": "@id"},
"actions": {"@id": "ts:hasAction", "@type": "@id"}
“events": {"@id": "ts:hasEvent", "@type": "@id"}
“properties": {"@id": "ts:hasProperty", "@type": "@id"}

@type:@id maps the key to a URI. for senml I might start with these 
maps in the context (where some is also defined somewhere).

“bn": {"@id": “some:baseURI", "@type": "@id"}
“i": {"@id": “some:collectionItems", "@type": "@id”}
“l": {"@id": “some:collectionLinks", "@type": "@id"}
“n": {"@id": “some:baseURI", "@type": "@id”}
“v": {"@id": “some:numberValue", "@type": "@id"}
“vs": {"@id": “some:stringValue", "@type": "@id"}
“vb": {"@id": “some:booleanValue", "@type": "@id”}

and define xsd types, etc. at the referenced URI in some namespace, 
but there are other ways that the tools could also comprehend.

> If it is possible -- great, and it might serve as a criterion for a
> bufferlessly parsable SenML that it can be transformed using JSON-LD.
> But as far as I remember, it can't do that even for -01, and unless that
> can be fixed, I don't see much of a point in using it as an example.
> 
> Best regards
> Christian
> 
> -- 
> Christian Amsüss                      | Energy Harvesting Solutions GmbH
> founder, system architect             | headquarter:
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