IOTDB.org•

Semantic Metadata for the Internet of Things

Tuesday, 13 May, 14

David Janes@dpjanes

davidjanes@iotdb.orghttp://imadeit.davidjanes.com/

May 2014

Tuesday, 13 May, 14

Semantic Metadata

Tuesday, 13 May, 14

What is it?

{ "on" : true, "temperature" : 225}

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Primary issues

• What does each field mean?

• What does this message represent?

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Secondary issues

• Where is it?

• Who can access it?

• Not addressed in this presentation!

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What does each field mean?

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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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Units

• What does temperature refer to?

• degrees Celsius, Fahrenheit … or Kelvin?

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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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What does a message represent?

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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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Classes?

• No!

• There is no neat hierarchy of Things

• Things can fall into many messy categories

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Facets

• our solution is “Facets”

• a Thing may have many Facets, e.g.

• appliance, toaster, oven, sensor, a Wikipedia page…

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@id

• A constant unique identifier for this Thing

• a IRI!

• It does not “evolve” as new readings are made

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Placement

• Where is it?

• Address

• Lat / Lon

• Building, Floor, Room

• Person? Animal?

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How to do it

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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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JSON-LD

• describe Linked Data using JSON

• easy-to-use (sorta)

• plenty o’ software and tools

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IOTDB Models

• Write in Javascript

• easy to test, easy to understand

• Compiles to JSON-LD

•npm install iotdb

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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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…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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Putting it all together

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Data

{ "@context": "./meta-iri.jsonld", "on": true, "temperature": 225}

Note: @context is just one way of doing this!

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Metadata…{ "@id": "#on", "@type": "iot:attribute", "iot:purpose": [ "iot-attribute:on", "iot-attribute:control" ], "iot-js:type": "iot-js:boolean"}…

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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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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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#iotdb

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Get in touch!

David Janes@dpjanes

davidjanes@iotdb.orghttp://imadeit.davidjanes.com/

Tuesday, 13 May, 14