Linked Data knowledge sources such as DBpedia, Freebase, and Wikidata currently offer large amounts of factual data. As the amount of information that can be grasped by users is limited, data summaries are needed. If a summary relates to a specific entity we refer to it as entity summarization. Unfortunately, in many settings, the summaries of entities are tightly bound to user interfaces. This practice poses problems for efficient and objective comparison and evaluation. In this paper we focus on the question of how to make summaries exchangeable between multiple interfaces and multiple summarization services in order to facilitate evaluation and testing. We introduce SUMMA, an API definition that enables to decouple generation and presentation of summaries. It enables multiple consumers to retrieve summaries from multiple providers in a unified and lightweight way.

1. KIT – University of the State of Baden-Wuerttemberg and
National Research Center of the Helmholtz Association
Institute of Applied Informatics and Formal Description Methods
www.kit.edu
SUMMA: A Common API for Linked Data Entity Summaries
Andreas Thalhammer and Steffen Stadtmüller
15th International Conference on Web Engineering (ICWE 2015) 25.06.2015
Rotterdam

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Outline
1. Motivation
2. SUMMA API definition
3. Implementation
4. Evaluation
5. Related work
6. Conclusions
7. Future work
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015

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Motivation
RDF graphs enable to represent all available information about entities:
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
Pulp
Fiction
John
Travolta
Uma
Thurman
Quentin
Tarantino
1994
178
Bruce
Willis
runtime
(minutes)
year
starring
starring
starring
director
Kill Bill
Vol. 1
2003
112
runtime
(minutes)
year
starring
director

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Motivation
RDF graphs enable to represent all available information about entities:
Problems:
Untidy visualization of specific entities with a graph
 Feature-based representation
Many entities are involved in more than 1000 relations
 Entity summarization
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
Pulp
Fiction
John
Travolta
Uma
Thurman
Quentin
Tarantino
1994
178
Bruce
Willis
runtime
(minutes)
year
starring
starring
starring
director
Pulp Fiction
Year: 1994
Runtime (minutes): 178
Director: Quentin Tarantino
Starring: Bruce Willis
John Travolta
Uma Thurman
Samuel L. Jackson
Harvey Keitel
Tim Roth
Lawrence Bender
Amanda Plummer
Eric Stoltz
Peter Greene
Phil LaMarr
Julia Sweeney
Bur Steers

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Motivation
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
(Source: http://bing.com)
(Source: http://bbc.co.uk)

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Motivation
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
(Source: http://bing.com)
(Source: http://bbc.co.uk)
http://rdf.freebase.com/ns/location.country.capital http://rdf.freebase.com/ns/m.0156q
http://rdf.freebase.com/ns/0345h

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Motivation
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
Problem: Tight coupling
low interoperability
low compatibility
Solution: Decoupling
Servers Clients ClientServers
Separate Servers and Clients Summarization mashups become possible
SUMMA SUMMA SUMMA

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Motivation
Quantitative evaluation:
Qualitative evaluation:
A/B-Testing:
Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
25.06.2015
Comparator

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SUMMA API definition
Producing a summary of an entity
What is needed:
URI (of the entity e) – the entity needs to be identified
k (number) – an upper limit of facts related to e
What could be needed:
Multi-language support
Statement groups (e.g., biographical data)
Restriction to specific properties
Multi-hop search space
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
PF
JT
VV
actor
role
_:
starring
Angela Merkel
Date of birth: July 17, 1954
Place of birth: Hamburg (1,73 mio, 2013)

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SUMMA API definition
The SUMMA API involves:
SUMMA Vocabulary
RESTful interaction
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015

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SUMMA API definition
SUMMA Vocabulary:
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
summa:Summary
xsd:positiveInteger
summa:topK
summa:entity
rdfs:Resource
xsd:String
summa:language
summa:fixedProperty
rdf:Property
summa:statement
rdf:Statement
xsd:positiveInteger
summa:maxHops
summa:SummaryGroup
summa:group
summa:path

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SUMMA API definition
Vocabulary:
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
@prefix : <http://purl.org/voc/summa/>.
[ a :Summary ;
:entity dbpedia:Barack_Obama ;
:topK "2"^^xsd:positiveInteger .
:language "en" ;
:maxHops “1"^^xsd:positiveInteger ;
:fixedPredicate dbpedia-owl:birthPlace
]

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SUMMA API definition
Interaction:
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
Client Server
POST [ a :Summary;
:entity dbpedia:Barack_Obama; :topK 10 ] .
201 CREATED
Location: http://example.com/
summary?entity=dbpedia:Barack_Obama&topK=10
@ prefix summa: <http://purl.org/voc/summa/> .
...
GET http://example.com/
summary?entity=dbpedia:Barack_Obama&topK=10
200 OK
@ prefix summa: <http://purl.org/voc/summa/> .
...

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SUMMA API definition
SUMMA Vocabulary:
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
<http://km.aifb.kit.edu/summaServer/sum?entity=http://dbpedia.org/resour
ce/Barack_Obama&topK=2&maxHops=1&language=enhttp://dbpedia.
org/ontology/birthPlace> a <http://purl.org/voc/summa/Summary> ;
....
summa:statement [ rdf:type rdf :Statement ;
rdf:subject dbpedia:Barack_Obama ;
rdf:predicate dbpedia-owl:birthPlace ;
rdf:object dbpedia:Honululu ;
vrank:hasRank [ vrank:rankValue " 5512.0" ^^ xsd:double ]
]
...
dbpedia:Honolulu rdfs:label "Honolulu"@en .
...

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Implementation
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
<script>
summa("http://dbpedia.org/resource/Marie_Curie", 10, "en", null, "summary1",
" http://km.aifb.kit.edu/summa/summarum") ;
summa("http://dbpedia.org/resource/Marie_Curie", 10, "en", null, "summary2“,
"http://km.aifb.kit.edu/summaServer/sum") ;
...
https://github.com/athalhammer/summaServer
https://github.com/athalhammer/summaClient
http://people.aifb.kit.edu/ath/summaClient

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Evaluation
Search Engines:
Google Knowledge Graph
Microsoft Bing Satori/Snapshots
Yahoo Knowledge
News Portals (Alexa Top 25 News sites):
Forbes
BBC News
Could the user interfaces be generated with data from the
SUMMA API without changing their layout?
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015

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Evaluation
Features:
Property Restriction
Statement Groups
Multi-hop Search Space
Languages
Five entities:
Spain (country)
Dirk Nowitzki (person/athlete)
Ramones (band)
SAP (company/organization)
Inglourious Basterds (movie)
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
(Source: http://google.com)

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Evaluation
Results:
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015

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Related work
RDF data access via middle layers:
Pubby [1]
The Linked Data API [2]
RDF content selection and ranking:
Fresnel - Display Vocabulary for RDF [3]
vRank Vocabulary [4]
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015

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Conclusions
Decouple user interface from actual entity summarization
system by defining a common API.
Light-weight and extensible vocabulary and interaction
mechanism.
Reference implementations and their source code are
publicly available.
Evaluation demonstrates applicability in real-world
scenarios.
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015

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Future work
Build adapters to Google Knowledge Graph, Microsoft Bing
Satori/Snapshots, Yahoo Knowledge.
Implement a platform where SUMMA services can be
registered and (re-)used.
Extend the vocabulary and interaction mechanism towards
user context and personalization factors.
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015

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SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015
Questions?
andreas.thalhammer@kit.edu
@thalhamm

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Bibliography
[1] http://wifo5-03.informatik.uni-mannheim.de/pubby/
[2] https://code.google.com/p/linked-data-api/
[3] Christian Bizer, Emmanuel Pietriga, David Karger, and Ryan Lee.
Fresnel: A Browser-Independent Presentation Vocabulary for RDF. In
Proc. of 5th International Semantic Web Conference, Athens, GA, USA,
November 5-9, 2006, LNCS 4273, 2006.
[4] Antonio Roa-Valverde, Andreas Thalhammer, Ioan Toma, and
Miguel-Angel Sicilia. Towards a formal model for sharing and reusing
ranking computations. In Proc. of the 6th Intl. Workshop on Ranking in
Databases In conjunction with VLDB 2012, 2012.
25.06.2015 Andreas Thalhammer and Steffen Stadtmüller
SUMMA: A Common API for Linked Data Entity Summaries
ICWE 2015