-
Notifications
You must be signed in to change notification settings - Fork 0
Instructions
The content formats used are application/link-format+json, application/senml+json (draft-01) and application/collection+senml+json.
link-format+json is used for link operations and senml+json is used for data items and form items. collection+senl+json is for constructing or inspecting items and links together as a collection.
An index has only links but allows adding links with POST and modifying links with PATCH according to CoRE Resource Directory
For example, you can do: GET http://104.131.134.13:8000/index?rt=thing (accept: application/link-format+json) and get a link to a thing:
[
{
"rt": [
"light",
"thing"
],
"href": "/light/"
}
]
Then you can use the relative reference returned to construct the URL for the next step"
GET http://104.131.134.13:8000/light/ (accept: application/link-format+json) and get links to its (subresource) capabilities:
[
{
"href": "",
"rel": [
"self"
]
},
{
"rt": [
"capability",
"onoff"
],
"href": "onOff",
"rel": "sub"
},
{
"rt": [
"capability",
"colorhs"
],
"href": "colorHS",
"rel": "sub"
},
{
"rt": [
"capability",
"brightness"
],
"href": "brightness",
"rel": "sub"
}
]
Then we can GET http://104.131.134.13:8000/light/onOff/ (accept: application/link-format+json) and receive the following representation which contains links to property subresources and a link which points to a form. The link describes it as a ["form" "item"] that can ["change" "action"] the context resource which is type onoff (self link should have the rt=onoff attrval)
[
{
"href": "",
"rel": [
"self"
]
},
{
"rt": [
"action",
"change"
],
"href": "change",
"rel": [
"form",
"item"
]
},
{
"rt": [
"property",
"currentstate"
],
"href": "currentState",
"rel": "sub"
},
{
"rt": [
"property",
"targetstate"
],
"href": "targetState",
"rel": "sub"
},
{
"rt": [
"property",
"delaytime"
],
"href": "delayTime",
"rel": "sub"
}
]
If you use the schema, you might know ahead of time that you are looking for a "change" ;-) so you could just ask for it: GET http://104.131.134.13:8000/light/onOff/?rt=change and get the link you are seeking:
[
{
"rt": [
"action",
"change"
],
"href": "change",
"rel": [
"form",
"item"
]
}
]
So then you GET the form (in SenML content type for now...): GET http://104.131.134.13:8000/light/onOff/change (accept: application/senml+json)
{
"bn": "/light/onOff/",
"e": [
{
"fv": {
"rel": "action",
"href": "actuation",
"template": [
],
"type": [
"change",
"action"
],
"method": "POST",
"ct": "application/collection+senml+json"
},
"n": "change"
}
]
}
The form item retrieved describes how to change onoff; which is by performing a method=POST to the resource at href=actuation constructed according to a template (TBD) using the content format ct=application/collection+senml+json
Here is the entire "onOff" resource representation with links and items in collection format.
{
"bn": "/light/onOff/",
"e": [
{
"fv": {
"rel": "action",
"href": "actuation",
"template": [
],
"type": [
"change",
"action"
],
"method": "POST",
"ct": "application/collection+senml+json"
},
"n": "change"
}
],
"l": [
{
"href": "",
"rel": [
"self"
]
},
{
"rt": [
"action",
"change"
],
"href": "change",
"rel": [
"form",
"item"
]
},
{
"rt": [
"property",
"currentstate"
],
"href": "currentState",
"rel": "sub"
},
{
"rt": [
"property",
"targetstate"
],
"href": "targetState",
"rel": "sub"
},
{
"rt": [
"property",
"delaytime"
],
"href": "delayTime",
"rel": "sub"
}
]
}
There is a meta-catalog example at thingschema.org that has an entry pointing to this index to bootstrap the discovery:
{
"href": "http://104.131.134.13:8000/index",
"rt": "index",
"ct": ["application/link-format+json", "application/collection+senml+json"]
"comment": "hypermedia demonstrator discovery"
}
The toolkit is written in python and is Apache 2 licenced. It can be downloaded from the github repository at:
[Machine Hypermedia Toolkit source repository and installation instructions] (https://github.com/connectIOT/MachineHypermediaToolkit)
There is a public resource for hosting the schema and JSON-LD context files. thingschema.org
The content of thingschema.org is stored at a github repository: thingschema-content
thingschema.org serves a standard JSON-LD context file that can be used by including "@context": "http://thingschema.org" in your JSON-LD file
In addition there is a WoT interaction model schema and a domain-specific schema for lighting.
In the examples directory there is a model for an instance of a light, and a meta-catalog file with pointers to other resources like IETF Resource Directories, W3C WoT Thingdescriptions, hypercats, or other discovery resources.
Context file: http://thingschema.org/context.jsonld
W3C Interaction Model : http://thingschema.org/wot.jsonld
Lighting domain model: http://thingschema.org/light.jsonld
Meta-catalog: http://thingschema.org/examples/catalogs.jsonld
Example light model: http://thingschema.org/examples/lightmodel.jsonld
Example IPSO Smart Object constructor: http://thingschema.org/examples/IPSO-rm.json
The JSON-LD Playground resource can be used to evaluate semantic graphs produced by these schemas and models. For example, to view a triples representation of the lighting model example, paste the URL for the light model example json file: http://thingschema.org/examples/lightmodel.jsonld into the URL box on the JSON-LD Playground page at: http://json-ld.org/playground/ and click the tab for N-Quads and the model is displayed. Note that this is the model for the live example above:
_:b0 <http://www.w3.org/2000/01/rdf-schema#Resource> _:b1 .
_:b0 <http://www.w3.org/2000/01/rdf-schema#Resource> _:b18 .
_:b0 <http://www.w3.org/2000/01/rdf-schema#label> "light" .
_:b1 <http://thingschema.org/name> "light" .
_:b1 <http://thingschema.org/schema#hasCapability> _:b2 .
_:b1 <http://thingschema.org/schema#hasCapability> _:b7 .
_:b1 <http://thingschema.org/schema#hasCapability> _:b9 .
_:b1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://thingschema.org/light> .
_:b10 <http://thingschema.org/name> "change" .
_:b10 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://thingschema.org/change> .
_:b11 <http://thingschema.org/name> "move" .
(...)
_:b9 <http://thingschema.org/schema#hasProperty> _:b15 .
_:b9 <http://thingschema.org/schema#hasProperty> _:b16 .
_:b9 <http://thingschema.org/schema#hasProperty> _:b17 .
_:b9 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://thingschema.org/brightness> .