CLODA: A Crowdsourced Linked Open Data Architecture

Dagstuhl Seminar 10042, Demetris Zeinalipour, University of Cyprus, 26/1/2010

CLODA: A Crowdsourced
Linked Open Data Architecture
Georgios Larkou, Julia Metochi
Georgios Chatzimilioudis and
Demetrios Zeinalipour-Yazti
Data Management Systems Laboratory
Department of Computer Science
University of Cyprus
http://dmsl.cs.ucy.ac.cy/
First IEEE Intl. Workshop on Mobile Data Management, Mining and Computing on
Social Networks (MobiSocial), co-located with IEEE MDM'13, June 3, 2013, Milan, Italy.
1
© Larkou, Metochi, Chatzimilioudis and Zeinalipour-Yazti, Mobisocial'13, Milan, Italy


Crowdsourcing Definitions

•

Crowdsourcing = Crowd + Outsourcing
–

•

Jeff Howe (2006). "The Rise of Crowdsourcing". Wired.

Definition from Wikipedia:
–

"Crowdsourcing refers to a distributed
problem-solving model in which a crowd of
undefined size is engaged in the task of
solving a complex problem through an open
call"
“Crowdsourcing with Smartphones”, Georgios Chatzimiloudis, Andreas Konstantinidis, Christos Laoudias, Demetrios ZeinalipourYazti, IEEE Internet Computing, Special Issue: Sep/Oct 2012 - Crowdsourcing, May 2012. IEEE Press, Volume 16, Pages: 36-44,
2012.
Presenter: Demetris Zeinalipour, http://dmsl.cs.ucy.ac.cy/

3


Crowdsourcing StakeHolders
Open Call (Task)

Solutions

Requester
(Crowdsourcer)

Rewards

Workers

Platform

(Solvers)
4


Crowdsourcing Incentives

• Tangible (Monetary) Incentives
– Cash, Credit or Gifts (MTurk, Kickstarter)
– Unintended or as-a-by-product (reCaptchas)

• Ethical Incentives
– Socialize & Fun
– Earn Prestige
– Altruism
– Learn something New

• Usually a combination of several
incentives

5


CLODA Motivation
Collect & Link Open and Close Data with
smartphones through an open call for ethical benefit

b

a

Linked Open
Data (LOD)
(Freebase,
DBPedia)

Closed Data:
Web 2.0 APIs (Google,
Twitter, Facebook)

CLODA
Prototype

c

Sensor / Geo Data
Collect
Reward

Verification

CLODA (LOD)

d


6


Linked Open Data (LOD)
• Linked data refers to web accessible data
(HTTP/URI addressable) that is structured
(RDF) to allow computer link and query
(SPARQL) the data [ aka 4 principles ]
• Conceived by Tim Berners-Lee and realized by
the Semantic Web Community.
– Tim Berners-Lee (2006). "Linked Data—Design Issues". W3C.

• Linked Open Datasets (LOD):
–
–
–
–
–

DBPedia (3.6M things describing Wikipedia)
GeoNames (describing 7.5M Geographic features)
YAGO & YAGO2 (combining Wikipedia, GeoNames and others)
Freebase (39M things - Google's LOD project!)
FOAF (describing Demetris Zeinalipour, http://dmsl.cs.ucy.ac.cy/
People – Relationships –Open Social Net!) 7
Presenter:


Traditional LOD (RDF)
• DBPedia Example: LOD describing 3.64M
Wikipedia things out of which 1.83M are
classified in a consistent ontology
– 416,000 persons, 526,000 places, 106,000 music albums,
60,000 films, 17,500 video games, 169,000 organizations,
183,000 species and 5,400 diseases
Infobox example


8


LOD the Google (JSON) Way!
• Freebase Example: another LOD by Google.

Instances

Relationships


9


LOD is Interlinked & Annotated
LOD is interlinked, e.g., Freebase points to Dbpedia
predicates …

http://dbpedia.org/page/Manchester

10


LOD is Highly Interlinked!

http://www.stateofsearch.com/search-in-the-knowledge-graph-era/

11


LOD can be Queried!
LOD can be queried!, e.g., Freebase with MQL Queries
(JSON encoded like Web2.0 APIs)

Resembles
Xpath
Querying
MQL Queries

12


CLODA Motivation
Closed Data:
Twitter, Facebook)

Linked Open
Data (LOD)
(Freebase,
DBPedia)

CLODA
Prototype

Sensor / Geo Data
Collect
Reward

Verification

CLODA LOD

13


Web1.0: The Unstructured Web
http://books.google.com/

(content in HTML
only apprehensible to
User)


14


Web2.0: The Structured but Closed Web
https://www.googleapis.com/books/v1/volumes?q=databases

content in XML/JSON
apprehensible to Computer

This web is closed: Requires
Keys to access (OAUTH) and
has download quotas


15


Web2.0: The Structured but Closed Web
In fact, Web2.0 Services are omnipresent!
(Google, Twitter, Facebook, Youtube, Linkedin, …)
http://www.programmableweb.com/ - 7800 APIs!!! + 6800 Mashups!

quota

https://code.google.com/apis

16


CLODA Motivation
Closed Data:
Twitter, Facebook)

Linked Open
Data (LOD)
(Freebase,
DBPedia)

CLODA
Prototype

Sensor / Geo Data
Collect
Reward

Verification

CLODA LOD

17


CLODA: Indoor Localization
•

•

•

Numerous ways to localize without power-hungry GPS
but most of the solutions rely on additional hardware
(RFID, sensor networks, etc.)
Smartphones can nowadays localize off-the-shelf with
onboard sensors and WiFi signal fingerprints (coined
Hybrid Localization)
These solutions require that services acquire local
data through Crowdsourcing (e.g., Google Indoor)
–
–
–

–

Building RadioMaps, MagnetometerMap, etc.
[Airplace] "The Airplace Indoor Positioning Platform for Android
Smartphones", C. Laoudias et. al., Best Demo Award at IEEE MDM'12.
[HybridCywee] "Demo: the airplace indoor positioning platform", C.-L. Li,
C. Laoudias, G. Larkou, Y.-K. Tsai, D. Zeinalipour-Yazti and C. G.
Panayiotou, in ACM Mobisys'13. Video at: http://youtu.be/DyvQLSuI00I
Wifislam.com (bought recently by Apple for 20M)

18


CLODA: Scanning Items
Preview

LOD

LOD

Scan & Link


19


CLODA: Scanning Items


20


CLODA: Indoor Localization
Founded on prior work

Cywee / Airplace
http://youtu.be/DyvQLSuI00I

Airplace and Anyplace
(Navigate) seamlessly indoor or outdoor
http://anyplace.cs.ucy.ac.cy/


21


CLODA Motivation
Closed Data:
Twitter, Facebook)

Linked Open
Data (LOD)
(Freebase,
DBPedia)

CLODA
Prototype

Sensor / Geo Data
Collect
Reward

Verification

CLODA LOD

22


NoSQL DataStore: CouchDB
Document in CouchDB

Map Function
function(doc) {
for (i in doc.authors) {
author = doc.authors[i];
emit(doc._id, author);
}
}

Results (through REST/HTTP or Futon)


23


NoSQL DataStore: CouchDB
Export JSON Data to RDF with
Sessel (CouchApp that
generates RDF triples from
CouchDB documents)


24


CLODA Motivation
Closed Data:
Twitter, Facebook)

Linked Open
Data (LOD)
(Freebase,
DBPedia)

CLODA
Prototype

Sensor / Geo Data
Collect
Reward

Verification

Last step essentially
provided interlinking
CLODA LOD
with existing LOD

25


CLODA on the LOD Graph!
CLODA

http://www.stateofsearch.com/search-in-the-knowledge-graph-era/

26


CLODA Incentives
• Incentives:
– Ethical Benefit
• Similar to people-centric sensing / wardriving

– Enhance collaboration between users
• Richer querying possibilities in the future.

– Might be imposed by an Organization.
• E.g., Inventory Management in a Hospital


27


CLODA Quality Issues
• Data Quality / Data Freshness
– LOD data suffers from both of these aspects
– Crowdsourcing offers Freshness but still lacks
explicit Quality guarantees (repeat N times then
majority vote)

• Possible Solutions: Integrate Location-aware
Techniques to validate data added and linked
– Task of Identifying the neighbors of all users
continuously with Proximity, see IEEE MDM'12.
– Task of Identifying similarly moving users with
SmartTrace, see IEEE TKDE, June, 2013.

28


CLODA Testbed Issues
• Currently, there are no testbeds (like motelab, planetlab)
for realistically prototyping Smartphone Network
applications and protocols at a large scale.
• Currently applications are tested in emulators.
– Sensors are not emulated. 
– Reprogramming is difficult. 
• SmartLab (http://smartlab.cs.ucy.ac.cy/) is a first-of-akind programmable cloud of 40+ smartphones
deployed at our department enabling a new line of
systems-oriented research on smartphones.
"Crowdsourcing with Smartphones", Georgios Chatzimiloudis, Andreas Konstantinides, Christos Laoudias, Demetrios
Zeinalipour-Yazti IEEE Internet Computing (IC '12), Special Issue: Sep/Oct 2012 - Crowdsourcing, May 2012. IEEE
Press, 2012
"Demo: A Programming Cloud of Smartphones", A. Konstantinidis, C. Costa, G. Larkou and D. ZeinalipourYazti, "Demo at the 10th International Conference on Mobile Systems, Applications and Services" (Mobisys '12),
Low Wood Bay, Lake District, UK, 2012.
29



SmartLab: Massive smartphone simulations with
our first global open smartphone IaaS cloud –
http://smartlab.cs.ucy.ac.cy/

Static Androids

Mobile Androids

[SmartLab] "Demo: a programming cloud of smartphones", A. Konstantinidis, C.
Costa, G. Larkou, D. Zeinalipour-Yazti, In ACM Mobisys '12. [ By our
Group ]

30



http://smartlab.cs.ucy.ac.cy/

31


CLODA: A Crowdsourced
Linked Open Data Architecture
Thanks! Questions?
Georgios Larkou, Julia Metochi
Georgios Chatzimilioudis and
Demetrios Zeinalipour-Yazti
http://dmsl.cs.ucy.ac.cy/
First IEEE Intl. Workshop on Mobile Data Management, Mining and Computing on
Social Networks (MobiSocial), co-located with IEEE MDM'13, June 3, 2013, Milan, Italy.
32
© Larkou, Metochi, Chatzimilioudis and Zeinalipour-Yazti, Mobisocial'13, Milan, Italy

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