Coordination of Resource-Constrained Devices through aDistributed Semantic Space

Aitor Gomez-Goiri

DeustoTech - Deusto Institute of Technology, University of Deustohttp://www.morelab.deusto.es

February 20, 2013

Where do I come from?

Coordination of Constrained devices Where do I come from? 3 / 42

Coordination of Constrained devices Where do I come from? 4 / 42

Coordination of Constrained devices Where do I come from? 5 / 42

Internet of Services

Web of Data

Smart Environments

Internet of Things

Location Systems

www.morelab.deusto.es

Internet of Services

Web of Data

Smart Environments

Internet of Things

Location Systems

www.morelab.deusto.es

What do I do?

Tuple Spaces Semantic Web

Ubiquitouscomputing

Tuple Spaces

Coupling

⇓nodes coordinate writing and reading information in a

common space

I Location autonomyI Reference autonomyI Time autonomy

Coordination of Constrained devices What do I do? 11 / 42

Tuple Spaces

Coupling

⇓nodes coordinate writing and reading information in a

common spaceI Location autonomyI Reference autonomyI Time autonomy

Coordination of Constrained devices What do I do? 11 / 42

The Semantic Web

Coupling on nodes’ internal data-schema

⇓Add semantic to achieve

application-level interoperabilityBackup

Coordination of Constrained devices What do I do? 12 / 42

Tuple Spaces Semantic Web

TSC

Backup

Tuple Spaces Semantic Web

Ubiquitouscomputing

WoTMobilecomp

Challenge

Adapt TSC for resource constrained devices

1. Knowledge dissemination

2. Compatibility with REST (& the WoT)

Coordination of Constrained devices Lightweight TSC middleware 15 / 42

Challenge

Adapt TSC for resource constrained devices

1. Knowledge dissemination

2. Compatibility with REST (& the WoT)

Coordination of Constrained devices Lightweight TSC middleware 15 / 42

Knowledge dissemination

I Too much load for small devices

I Delegate into intermediariesI Everything related wih the semanticI Devices manage their own semantic data

Coordination of Constrained devices Lightweight TSC middleware 16 / 42

Compatibility with the WoT/REST

I Provide content using semantic formatI RESTfullyI Compatible with WoT

REST* TSCROA x xResources

x xidentified by URIs

OperationsGET, PUT,

Write, read, takePOST, DELETE

Representation HTML, Json,... Full semantics

I On top of that, we build a TSC middleware

Coordination of Constrained devices Lightweight TSC middleware 17 / 42

o o

TS

https://github.com/gomezgoiri/otsopack

...and how to build it?(searching)

Starting point (assumptions)

I Each device manages its own informationI The space is distributed among all the participantsI Each device interrogates others

Coordination of Constrained devices Lightweight TSC middleware 20 / 42

Who to query?

To all (naive)

To whoever has a relevant answer for me

⇓need to know about the information others have

Coordination of Constrained devices Lightweight TSC middleware 21 / 42

Who to query?

To all (naive)

To whoever has a relevant answer for me⇓

need to know about the information others have

Coordination of Constrained devices Lightweight TSC middleware 21 / 42

What should a node know from the rest?

General concepts or terminology (TBox)

implies sharing less information( the specific knowledge, ABox, changes too frequently )

Backup

Coordination of Constrained devices Lightweight TSC middleware 22 / 42

Energy-aware architecture

I Share clues through an intermediaryI dynamic roleI chosen according to its capacities

get clues

send clues

make clues

directly access to data

Coordination of Constrained devices Lightweight TSC middleware 23 / 42

Goal

nb oursStrategy

0

50000

100000

150000

200000

250000

300000

activ

e tim

e / n

ode

xbee foxg20galaxy_tabserverTypes of devices

0

50000

100000

150000

200000

250000

300000

activ

e tim

e / n

ode

oursnb

(16% less energy consumed without activity in a FoxG20)

Coordination of Constrained devices Lightweight TSC middleware 24 / 42

Conclusions

1. Indirect communication to ease developers tasks2. Promote end-to-end search3. Architecture driven by energy needs4. Light reasoners for small devices still needed

Coordination of Constrained devices Conclusions 25 / 42

Future work

I Enhance the mechanisms to act on the spaceI Consider queries for ABox knowledgeI Further tests in non-prototipical real-world

scenariosI Continue exploring its feasibility in other platforms

Coordination of Constrained devices Conclusions 26 / 42

Coordination of Constrained devices Conclusions 27 / 42

Aitor Gomez-Goiriaitor.gomez@deusto.es

http://aitor.gomezgoiri.net

Bibliography I

Payam Barnaghi, Wei Wang, Cory Henson, and Kerry Taylor.Semantics for the internet of things.International Journal on Semantic Web and InformationSystems, 8(1):1–21, 2012.

George Coulouris, Jean Dollimore, Tim Kindberg, and GordonBlair.Distributed Systems: Concepts and Design.Addison Wesley, 5 edition, 2012.

World Wide Web Consortium.W3c semantic web faq, August 2011.

D. Nardi and R.J. Brachman.An introduction to description logics.The description logic handbook: theory, implementation, andapplications, pages 1–40, 2003.

Coordination of Constrained devices Bibliography 28 / 42

Bibliography II

Coordination of Constrained devices Bibliography 29 / 42

Backup slides

Conceptual classification

Applications, services

Remote invocation(e.g. REST or WS.*)

Indirect communication(e.g. Tuple Spaces)

Underlying interprocess communication(sockets, message passing, multicast support, overlay networks)

Platform(operating system + hardware)

Middlewarelayers

[CDKB12]

Coordination of Constrained devices Backup slides 31 / 42

The Semantic Web in short

The vision of the Semantic Web is to extend principles ofthe Web from documents to data. Data should beaccessed using the general Web architecture using, e.g.,URI-s; data should be related to one another just asdocuments (or portions of documents) are already. Thisalso means creation of a common framework that allowsdata to be shared and reused across application,enterprise, and community boundaries, to be processedautomatically by tools as well as manually, includingrevealing possible new relationships among pieces ofdata. [Con11]

Back

Coordination of Constrained devices Backup slides 32 / 42

Semantics alone are not enough

Providing semantic descriptions alone does not providesemantic interoperability. [BWHT12]

I Agreement on ontological definitionsI ontology mapping and matchingI use of reference upper-level ontologies

I Semantics need to be processed and analyzedI interpret and create meaningful abstractionsI effective reasoning and processingI Should the ontologies be simpler and light weight for IoT?

Back

Coordination of Constrained devices Backup slides 33 / 42

Back

ssn:Observation

ssn:hasLocation

weather:RainfallObservation

rdfs:subClassOf

rdfs:rangedul:Entity

rdfs:domain

rdfs:subClassOf

someSpecificPropertyrdfs:range

rdfs:domain

?s rdf:type weather:RainfallObservation?s rdf:type ssn:Observation?s someSpecificProperty ?p?s ssn:hasLocation ?obizkaisense:ABANTO ?p ?o

TBox

TBox contains knowledge describing general propertiesof concepts or terminology.

[NB03]

I E.g. the device type or the elements it is made of.

Back

Coordination of Constrained devices Backup slides 35 / 42

ABox

ABox contains knowledge specific to the individuals ofthe domain of discourse.

[NB03]

I E.g. the mobile phone brand or the temperature sensed by athermometer.

Back

Coordination of Constrained devices Backup slides 36 / 42

Application 1: Security

I Security application monitors parametersI E.g. temperature, humidity & CO2 concentration

I Sensors deployed in an industrual facilityI Generates alarms different prioritiesI They are displayed in different devices

I E.g. visual and auditory alarms or in the managers the phoneI Using standards ontologies such as: SSN, SWEET

Coordination of Constrained devices Backup slides 37 / 42

Application 2: Home automation

I Devices deployed on an office: sensors and actuatorsI An application in a smartphone stores user’s preferencesI A node generates tasks to regulate the temperatureI Using standards ontologies such as: SSN, MUO, RECO

Coordination of Constrained devices Backup slides 38 / 42

Interoperability

I Both applications use SSN ontologyI Even if they were not designed with that purpose...

I App1 transparently uses App2’s dataI and vice versa

Back

Coordination of Constrained devices Backup slides 39 / 42

Energy consumption

Inactivityperiod

Period withcontinuous requests

Reasoning period0

100

200

300

400

500

600

700Av

erag

e po

wer

con

sum

ptio

n (m

W)

Back

Coordination of Constrained devices Backup slides 40 / 42

Use of Semantic Gateways

Sensors directly Use of semanticprovide data gatewayStrong nodes Really constrainedMost updated Possible CachingMore privacy controlAutonomy Dependency

(less flexible)

Coordination of Constrained devices Backup slides 41 / 42

All rights of images are reserved by theoriginal owners*, the rest of the content is licensed

under a Creative Commons by-sa 3.0 license.

* OpenStreetMap, Universidad de Deusto, Amortize, and Marco Crupi.