This document discusses increasing interoperability in the Web of Things (WoT). It proposes a hub-centric model where hubs standardize representations and protocols for connected "things" to simplify integration for application developers. The document outlines challenges to interoperability like defining things, their interactions and descriptions. It describes a UK project using hubs and a standardized API to demonstrate interoperability across domains. The document concludes by calling for continued work within the WoT community to further define common models, profiles and best practices to advance interoperability.

1. Toward Interoperability In a
Web of Things
Michael Blackstock, Rodger Lea
Media and Graphics Interdisciplinary Centre
University of British Columbia, Canada
Thursday, 12 September, 13

2. Motivation
The Web of Things promises to connect islands of things BUT
Developers are making independent decisions about “thing”
representations and protocols.
Often leave application and tool developers to ‘fill the gaps’
Full interoperability for all “things” is a massive undertaking
How can we increase interoperability while maintaining high degree of
innovation?
Are there ‘levels’ and a path toward increasing interoperability over time?
Explore an approach to standardization in WoT Community
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3. Web-enabled IoT
Products
Platforms
Hubs
Sensor Webs
Mashup Platforms and
Tools
WoT Today
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4. Many Standards Activities
Not all take a “hub centric” approach
Some are application or domain specific
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5. WoT Interop Challenges
What are Things? - buildings, sensors, tags, actuators,
organizations, services, people?
Thing Interaction - communicate between things and
applications, real time; web protocols and representations
Finding Things - search and discovery
Thing Identification - names, IDs, URLs
Describing Things - location, environment, capabilities
Securing Things - access control, licensing, confidentiality
Thing History - how, where do we store past state
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6. Toward Interoperability
Significant cooperation and widespread agreement on many issues is
needed
Need to understand the benefits and costs of greater interop including
added complexity and possibly limits on innovation
Suggest a hub-centric model
each hub addresses these issues
focus on needs of application and mashup developers
reduces integration task, many things on fewer hubs.
Staged approach - agree on some foundational technologies then build
as community evolves
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7. ProfilesHubModel
Levels of Interoperability
WoT Core
Clarify best practices
for web-enabling the
IoT.
Minimal interoperability
using the web leaving
app and tool
developers to do more
of the work.
Define common
models
e.g. catalogs, things,
groups of things
Toward simpler
adapters and limited
interop
Implementation of
model and decisions
on resources and
representations,
access control and
security.
Direct code reuse
between hubs.
Agree on ontologies
and semantics
allowing deeper
integration. Little or
no adaptation
required.
Iterate: refine models,
implementation and profiles
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8. UK TSB Project
Technology Strategy Board: UK govt funded org
designed to help companies innovate
IoT Ecosystem Demonstrator: 8m GBP ($12m) for 8
projects for 1 year with a further 4m follow on
Key objective is to achieve (a degree of) interoperability
across variety of domains
“stimulate the development of an open application and
services ecosystem in the Internet of Things”
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9. Project Overviews
Transportation
Built Environment
Home
Critical Infrastructure
Education
IoT-Bay
DISTANCE
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10. demonstrate how the IoT can drive innovation in the UK's Highways sector --
road networks
Focus applications
Gully Cleaning/flooding
Winter Maintenance/Gritting
Roadways/ Maintenance
Things - sensors & mobile apps
Roadway conditions
Lighting and signals
Drains, flooding patterns
Smart Streets
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11. Unified landing page
CKAN open data portal
static data resources
Web of Things Toolkit
sensor data
Interop API catalog
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12. Interop Approach
Web technologies at the
core, often using existing
WoT platforms
Each consortium
implements one or more
‘hubs’
Hubs communicate with
things to expose them to
applications
WoT Hub
ApplicationsApplicationsApplications
WoT
Hub
WoT
Hub
Other Hubs
Things and data
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13. TSB Project Interop API
Provide access to “things” -
data and information about
what that data represents.
Implement interface 1 between
applications and hub. Use data
from at least one other hub.
Minimal requirements for
exchanging catalogs of things
Needed for agreement on a
lightweight approach
WoT Hub
ApplicationsApplicationsApplications
WoT
Hub
WoT
Hub
Other Hubs
Things and data
2
3
1
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14. Specification
Model
catalogues - /cat returns a root catalogue object
sub-catalogs & items - URIs + metadata objects
CRUD catalogue operations
Simple search - metadata keys and values
Simple security - keys supplied in header; key distribution out of scope
Open for extensibility - very little required meta data
few defined resource formats, metadata, access to data, interaction
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15. { "item-metadata" : [ { "rel" : "urn:X-tsbiot:rels:isContentType",
"val" : "application/vnd.tsbiot.catalogue+json"
},
{ "rel" : "urn:X-tsbiot:rels:hasDescription:en",
"val" : "Smart Streets data catalogue that contains static resources."
},
{ "rel" : "urn:X-tsbiot:rels:supportsSearch",
"val" : "urn:X-tsbiot:search:simple"
}
],
"items" : [
{ "href" : "/cat/data/average-temperature-and-rainfall-england-and-wales",
"i-object-metadata" :
[ { "rel" : "urn:X-smartstreets:rels:lastUpdate",
"val" : "2013-06-19T00:00:20.761429"
},
{ "rel" : "urn:X-smartstreets:rels:hasId",
"val" : "3f952707-b04e-4a32-a807-a53b6fa0ee58"
},
{ "rel" : "urn:X-smartstreets:rels:hasLicense",
"val" : "UK Open Government Licence (OGL)"
},
{ "rel" : "urn:X-smartstreets:rels:hasName:en",
"val" : "average-temperature-and-rainfall-england-and-wales"
},
{ "rel" : "urn:X-tsbiot:rels:hasDescription:en",
"val" : "Average temperature and total rainfall in England and Wales : 1845 to 2010"
},
{ "rel" : "urn:X-smartstreets:rels:tags",
"val" : "average-rainfall,average-temprature,england,new-tag-1,new-tag-2,wales"
},
{ "rel" : "urn:X-smartstreets:rels:hasVisibility",
"val" : "public"
},
{ "rel" : "urn:X-tsbiot:rels:isContentType",
"val" : "application/vnd.tsbiot.catalogue+json"
},
{ "rel" : "urn:X-tsbiot:rels:supportsSearch",
"val" : "urn:X-tsbiot:search:simple"
},
{ "rel" : "urn:X-tsbiot:rels:containsContentType",
"val" : "application/vnd.ms-excel"
}
]
},
{ ... additional items ... }
]
}
Describe Catalogue
Supports Simple Search
Dataset Item URL
Meta data rel/val
Example Catalog
Mandatory meta data -
description and content type
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16. Challenges
Specification too narrow
easy agreement but limited interoperability and application usefulness
need to define relationships, data types, interaction
Simple Search is not so simple
doesn’t make sense to search by value in many cases (e.g. latitude)
underlying system often doesn’t permit search by certain relationships and values
Data vs. Metadata
search by data values (not just metadata) should be possible
no specification on the data formats for things yet
Catalog updates, security
replicate catalog or proxy? Force hubs to implement API?
exposed catalog depends on who is accessing it.
Missing features that become obvious with use - e.g. paging
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17. Conclusion and Next Steps
Toward interoperability
start simple - e.g. catalogs of things
Iteratively define and implement interoperable hub model and APIs
Start to define common profiles
WoT Community take a leadership role
Work toward a common position - paper?
Outline WoT Models, Patterns, Best Practices
Stronger links to TSB project
Collaborate within a standards group - W3C?
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18. Demo
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