What is it? You have a simple data record { "on": true, "temperature": 250 } but without metadata there's no easy way to know what this data really is. This short presentation shows how JSON-LD can be used to describe this data, the IOTDB vocabulary for the Internet of Things (https://iotdb.org/pub/), and how the IOTDB software can quickly and easily create "Models" of your data.

1. IOTDB.org
•
Semantic Metadata for
the Internet of Things
Tuesday, 13 May, 14

2. David Janes
@dpjanes
davidjanes@iotdb.org
http://imadeit.davidjanes.com/
May 2014
Tuesday, 13 May, 14

3. Semantic Metadata
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4. What is it?
{
"on" : true,
"temperature" : 225
}
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5. Primary issues
• What does each field mean?
• What does this message represent?
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6. Secondary issues
• Where is it?
• Who can access it?
• Not addressed in this presentation!
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7. What does each field
mean?
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8. Control or
Measurement?
• Does on mean:
• Turn it on? or
• Is it on?
• Does temperature mean:
• Set the temperature? or
• What is the temperature?
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9. Units
• What does temperature refer to?
• degrees Celsius, Fahrenheit … or Kelvin?
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10. And also...
• Is it measuring a specific substance, say O2
or CO concentration?
• we don’t want to mix these up!
• Axis (X /Y / Z)
• Related attributes, say the temperature you
are setting vs. the temperature it is
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11. What does a message
represent?
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12. What are we talking
about … or with?
• An oven?
• A toaster?
• A sensor in the Large Hadron Collider?
• This is a hard problem
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13. Classes?
• No!
• There is no neat hierarchy of Things
• Things can fall into many messy categories
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14. Facets
• our solution is “Facets”
• a Thing may have many Facets, e.g.
• appliance, toaster, oven, sensor, a Wikipedia
page…
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15. @id
• A constant unique identifier for this Thing
• a IRI!
• It does not “evolve” as new readings are
made
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16. Placement
• Where is it?
• Address
• Lat / Lon
• Building, Floor, Room
• Person? Animal?
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17. How to do it
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18. Linked Data
• The core of the Semantic Web
• Describe data using triples:
• two objects and their relationship
• Use IRIs to represent all those things
• IRIs go to web pages that “make sense”
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19. JSON-LD
• describe Linked Data using JSON
• easy-to-use (sorta)
• plenty o’ software and tools
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20. IOTDB Models
• Write in Javascript
• easy to test, easy to understand
• Compiles to JSON-LD
•npm install iotdb
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21. Write IOTDB Model…
iotdb.make_model('oven')
.attribute(
iotdb.control_boolean(":on")
)
.attribute(
iotdb.control_number(":temperature")
.unit(":temperature.si.celsius")
)
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22. …Get JSON-LD
…{
"@id": "#on",
"@type": "iot:attribute",
"iot:purpose": [
"iot-attribute:on",
"iot-attribute:control"
],
"iot-js:type": "iot-js:boolean"
}…
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23. Putting it all together
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24. Data
{
"@context": "./meta-iri.jsonld",
"on": true,
"temperature": 225
}
Note: @context is just one way of doing this!
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25. Metadata
…{
"@id": "#on",
"@type": "iot:attribute",
"iot:purpose": [
"iot-attribute:on",
"iot-attribute:control"
],
"iot-js:type": "iot-js:boolean"
}…
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26. N.B.
• The data does not have to be JSON!
• You don’t need to have IOTDB!
• You don’t need to use IOTDB IRIs (but you
should)
• https://iotdb.org/pub/
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27. Take aways
• describe the IoT using Linked Data
• Linked Data is IRIs
• IRIs for the IoT are defined by IOTDB
• but unlimited extensibility!
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28. #iotdb
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29. Get in touch!
David Janes
@dpjanes
davidjanes@iotdb.org
http://imadeit.davidjanes.com/
Tuesday, 13 May, 14