WoT Implementation With IoT Toolkit

Implementing the Web of Things Virtual Entity using IoT Toolkit

IoT Toolkit• https://github.com/connectIOT/iottoolkit • Project started in 2012• Experimental framework to investigate web

architecture for IoT• Core Ideas:– Web Objects – REST + Events– Hypermedia – Linked Data

Smart Object API• Web Object API to encapsulate a thing’s:– Properties – Events– Actions– Description

• Based on a core object model with protocol bindings and semantic bindings– HTTP, CoAP, MQTT– RDF, JSON-LD, CoRE Link-format

High Level SchemaSmartObject

Description

Agent

ObservableProperty

Description

Observer

PropertyOfInterest

SmartObject ClassOperation Action Data

Read Read Description Linked Data

Update Update Description Linked Data

Create Add New Resource Constructor

Delete Remove Resource

• Represents a thing• Container for encapsulation of other

resources• Can contain instances of SmartObjects• API reflects the thing description

Description ClassOperation Action Data

Read Read Description Linked Data

Update Update Description Linked Data

Create Add New Links Linked Data

Delete Remove Links Link Template

• Describes a thing or a resource in a thing• Sub-resource of SmartObject or

ObservableProperty• Links to resources, links about resources

Agent ClassOperation Action Data

Read List Handlers List of Handlers

Update N/A

Create Add New Handler Constructor Object

Delete Remove Handler

• Contains Handlers, which are actions invoked within an object

• Rules, filters, transforms, aggregations…• Handlers contain pointers to input and

output ObservableProperties

ObservableProperty ClassOperation Action Data

Read Get value Property Value

Update Replace Value New Value

Create Add New Resource e.g. Observer

Constructor Object

Delete Remove resource

• Represents a property of a thing• API reflects the value of the property• Zero or more per SmartObject• Can generate Events and invoke actions

through Observers

Observer ClassOperation Action Data

Read Get constructor Constructor Object

Update Modify Constructor Constructor Template

Create N/A

Delete Remove Self

• Endpoint for Events, sub resource of ObservableProperty

• Publisher, Subscriber, or Handler invoker• Describes the event to be generated or

received• Specifies conditions for generating events

PropertyOfInterest ClassOperation Action Data

Read Get value Property Value

Update Update Value New Value

Create N/A

Delete N/A

• Optional within ObservableProperty• Enables complex data types by invoking

custom methods • Time series data, structured objects

IoT Toolkit – Protocol Bindings

HTTP Server HTTP Client

CoAP ServerCoAP Client

MQTT Client

/

OP

OBS

OBS

OBS

Server Bindings to Object Tree

Client (Observer) Bindings to Resource Endpoints

IoT Toolkit Core - Objects and Resources