The document discusses data integration challenges and strategies within the context of various data sources, including sensors and relational databases, focusing on the rdb2rdf framework for transforming relational data into RDF for semantic querying. It highlights existing implementations, ongoing work in optimizing query rewriting, and applications in sensor networks, particularly in smart cities. Additionally, it mentions the importance of ontology-based querying and performance considerations in using different database management systems.

1. Data integration at our group:
ingredients and some
prospects
Credible workshop
Sophia-Antipolis, October 15th 2012
Oscar Corcho
ocorcho@fi.upm.es
Facultad de Informática, Universidad Politécnica de Madrid
Campus de Montegancedo s/n. 28660 Boadilla del Monte, Madrid, Spain
With contributions from: José Mora (OEG-UPM), Boris Villazón-Terrazas (OEG-UPM, now at
iSOCO), Jean Paul Calbimonte (OEG-UPM), Freddy Priyatna (OEG-UPM), Carlos Buil-Aranda
(OEG-UPM, now at PUC Chile)

2. Our data integration needs, problems (and challenges)
And data may be available from data
streams (e.g., sensors)
Need to submit SPARQL queries into
distributed SPARQL endpoints
Need to access heterogeneous relational
data sources (mainly in the area of Geography)
• Some of the databases are available
in different DBMSs
• And some of the data sources are
available as spreadsheets
• Furthermore, many of these datasets
are already published as Linked Data
2

3. Ingredients
100
80 thin applications (mas hups )
middleware
60 5 Reasoning Este
40
s emantic data integration and querying
Oeste
20 1 RDB2RDF
Norte
0
1er 3er 2 legacy
Sensor-based
3 query rewriting
Optimisations
data s ources
trim. regis tries
s ens or networks trim.
Federated Query
4 Processing
Linked Open Data Spreadsheets
From SemsorGrid4Env architecture (http://www.semsorgrid4env.eu/) 3

4. Disclaimer
When I talk about ontology-based querying,
I will be normally talking about SPARQL querying
4

5. 1. RDB2RDF
In other words, how to make relational data available as
RDF (and connected to ontologies)
5

6. RDB2RDF. Motivation
• A majority of dynamic Web content is backed by relational databases (RDB),
and so are many enterprise systems.
transformation
transformation engine
description
6

7. RDB2RDF. Query rewriting for OBDA with mappings
Q
Rewriting Mappings
Q’
There may be some
mappings to translate
between ontology and DB.
The rewriting should
consider those mappings.
7

8. RDB2RDF. Existing approaches
1
2
1. To build a new ontology from a
database schema and content
(direct mappings)
2. To map the ontology created in
approach (1) to a legacy ontology
3. To map an existing DB to a legacy
ontology
3
new ontology
existing ontology

9. OEG’s background knowledge in RDB2RDF
• R2O and ODEMapster
• GaV wrapper generation (no mediators)
• Syntactic sugar for the generation of SQL queries.
• Simple use of this language and processor in the domains of
fund finding, cultural information, and fisheries.
• NeOn Toolkit plugin for common mappings
Barrasa J, Corcho O, Gómez-Pérez A. (2004)
R2O, an extensible and semantically based
database-to-ontology mapping language. In:
Proceedings of the Second Workshop on
Semantic Web and Databases, SWDB 2004.
9

10. R2O (Relational-to-Ontology) Language
For concepts... One or more
concepts can be
extracted from a
A view maps exactly single data field (not
one concept in the in 1NF).
ontology.
For attributes...
A subset of the A column in a
columns in the view database view maps
map a concept in the directly an attribute
ontology. or a relation.
A subset (selection) of
the records of a A column in a
database view map a database view maps
concept in the an attribute or a
ontology. relation after some
transformation.
A subset of the
records of a database
view map a concept
in the onto. but the A set of columns in a
selection cannot be database view map
made using SQL. an attribute or a
relation.

11. The W3C RDB2RDF Working Group
• Created in 2007
• W3C Recommendations in
September 2012
• R2RML: RDB to RDF Mapping
Language -
http://www.w3.org/TR/r2rml/
• Direct Mapping -
http://www.w3.org/TR/rdb-
direct-mapping/
• R2RML and Direct Mapping
Test Cases -
http://www.w3.org/2001/sw/rdb
2rdf/test-cases/
• RDB2RDF Implementation
Report -
http://www.w3.org/2001/sw/rdb
2rdf/implementation-report/
11

12. R2RML example
12

13. Existing implementations
• OEG implementations
• http://code.google.com/p/oeg-obdi/
• https://github.com/jpcik/morph
• https://github.com/boricles/morph
RDB2RDF Implementation Report. Boris Villazón-Terrazas, Michael Hausenblas.
http://www.w3.org/2001/sw/rdb2rdf/implementation-report/
13

14. Ongoing work
• Provide a list of common patterns in R2RML
transformations, so that they can be reused
(increasing productivity)
• Sequeda J, Priyatna F, Villazón-Terrazas B. Relational
Database to RDF Mapping Patterns. In: Proceedings of the
3rd Workshop on Ontology Patterns (WOP2012).
• Villazón-Terrazas B, Priyatna F. Building Ontologies by
using Re-engineering Patterns and R2RML Mappings. In:
Proceedings of the 3rd Workshop on Ontology Patterns
(WOP2012).Priyatna
• http://mappingpedia.linkeddata.es/
• Improve our support at Morph for all test cases
• Adapt existing GUIs for the generation of mappings
(such as NeOn Toolkit’s one).
14

15. 2. R2RML query
rewriting optimisations
In other words, how to make this query rewriting
optimised, so that we don’t suffer from a bad efficiency
in our results
15

16. R2RML is now a W3C Recommendation
• That’s very good to ensure wide uptake, but…
• Implementations still suffer from their lack of
efficiency
• UltraWrap has shown that a similar performance can be
obtained with direct mappings on high-end databases
(Oracle, SQL Server)
• What happens with low-end databases (mySQL)?
16

17. Several works on SPARQL to SQL translation
• Barrasa J, Corcho O, Gómez-Pérez A. (2004) R2O, an
extensible and semantically based database-to-ontology
mapping language. In: Proceedings of the Second Workshop on
Semantic Web and Databases, SWDB 2004.
• R. Cyganiak. A relational algebra for sparql. Digital Media
Systems Laboratory. HP Laboratories Bristol. HPL-2005-170,
2005.
• B. Elliott, E. Cheng, C. Thomas-Ogbuji, and Z.M. Ozsoyoglu. A
complete translation from sparql into ecient sql. In Proceedings
of the 2009 International Database Engineering & Applications
Symposium, pages 31-42. ACM, 2009.
• A. Chebotko, S. Lu, and F. Fotouhi. Semantics preserving
sparql-to-sql translation. Data & Knowledge Engineering,
68(10):973-1000, 2009.
17

18. Chebotko’s query rewriting
18

19. Our proposal
19

20. An example. BSBM08
NATIVE
SELECT r.title, r.text, r.reviewDate, p.personID, p.name, r.rating1, r.rating2, r.rating3, r.rating4
FROM review r, person p
WHERE r.productID=55547 AND r.personID=p.personID AND r.language='en'
ORDER BY r.reviewDate desc
CHEBOTKO
SELECT var_rating2 AS rating2, var_reviewerName AS reviewerName, var_title AS title, var_rating1
AS rating1, var_reviewDate AS reviewDate, var_reviewer AS reviewer, var_rating3 AS rating3,
var_rating4 AS rating4, var_text AS text
FROM (SELECT *
FROM (SELECT uri_rating41477446315 AS uri_rating41477446315, var_rating2 AS var_rating2,
var_reviewer AS var_reviewer, uri_reviewDate750573656 AS uri_reviewDate750573656, var_rating4
AS var_rating4, var_rating1 AS var_rating1, var_text AS var_text, uri_title1963229325 AS
uri_title1963229325, var_rating3 AS var_rating3, uri_reviewer2088452952 AS
uri_reviewer2088452952, uri_rating21477446253 AS uri_rating21477446253, uri_text1457367120 AS
uri_text1457367120, uri_rating31477446284 AS uri_rating31477446284, uri_rating11477446222 AS
uri_rating11477446222, uri_reviewFor1499735727 AS uri_reviewFor1499735727, var_reviewDate AS
var_reviewDate, var_title AS var_title, uri_language269987354 AS uri_language269987354,
uri_Product555472014519903 AS uri_Product555472014519903, v_7634.var_review AS var_review,
var_reviewerName AS var_reviewerName, uri_name1396749066 AS uri_name1396749066, var_lang
AS var_lang
FROM (SELECT uri_reviewer2088452952 AS uri_reviewer2088452952, v_6537.var_review AS
var_review, uri_rating11477446222 AS uri_rating11477446222, uri_rating31477446284 AS
uri_rating31477446284, uri_Product555472014519903 AS uri_Product555472014519903,
uri_reviewFor1499735727 AS uri_reviewFor1499735727, var_rating2 AS var_rating2,
20

21. An example. BSBM08
OUR APPROACH
SELECT var_rating2 AS rating2, var_reviewDate AS reviewDate, var_rating4 AS rating4, var_rating1
AS rating1, var_reviewer AS reviewer, var_rating3 AS rating3, var_reviewerName AS reviewerName,
var_text AS text, var_title AS title
FROM (SELECT *
FROM (SELECT v_2660.var_reviewer AS var_reviewer, var_reviewDate AS var_reviewDate,
var_review AS var_review, uri_rating31477446284 AS uri_rating31477446284, uri_rating21477446253
AS uri_rating21477446253, uri_title1963229325 AS uri_title1963229325, var_rating3 AS var_rating3,
uri_reviewDate750573656 AS uri_reviewDate750573656, uri_reviewFor1499735727 AS
uri_reviewFor1499735727, uri_language269987354 AS uri_language269987354,
uri_name1396749066 AS uri_name1396749066, var_rating1 AS var_rating1, var_reviewerName AS
var_reviewerName, var_lang AS var_lang, uri_Product555472014519903 AS
uri_Product555472014519903, var_rating2 AS var_rating2, uri_rating41477446315 AS
uri_rating41477446315, var_title AS var_title, var_rating4 AS var_rating4, var_text AS var_text,
uri_rating11477446222 AS uri_rating11477446222, uri_text1457367120 AS uri_text1457367120,
uri_reviewer2088452952 AS uri_reviewer2088452952
FROM (SELECT v_8722.PERSONID AS var_reviewer, 'http://xmlns.com/foaf/0.1/name' AS
uri_name1396749066, v_8722.NAME AS var_reviewerName
FROM PERSON v_8722
WHERE (v_8722.NAME IS NOT NULL) ) v_2660
INNER JOIN (SELECT v_3353.REVIEWDATE AS var_reviewDate, 'http://www4.wiwiss.fu-
berlin.de/bizer/bsbm/v01/vocabulary/rating1' AS uri_rating11477446222, v_3353.REVIEWID AS
var_review, v_3353.TEXT AS var_text, 'http://purl.org/stuff/rev#reviewer' AS uri_reviewer2088452952,
v_3353.RATING1 AS var_rating1, 'http://www4.wiwiss.fu-berlin.de/bizer/bsbm/v01/vocabulary/rating2'
AS uri_rating21477446253, v_3353.TITLE AS var_title, 'http://www4.wiwiss.fu-
berlin.de/bizer/bsbm/v01/vocabulary/language' AS uri_language269987354, 'http://www4.wiwiss.fu-
berlin.de/bizer/bsbm/v01/vocabulary/reviewDate' AS uri_reviewDate750573656, 'http://www4.wiwiss.fu-
berlin.de/bizer/bsbm/v01/vocabulary/rating3' AS uri_rating31477446284, 'http://www4.wiwiss.fu-
21

22. Analysis with BSBM
SQL Server
mySQL
22

23. Ongoing work
• Writing the paper describing our optimisations
• Proposing a comprehensive benchmarking platform
to test R2RML-compliant query rewriting systems
• Extending our current work on the R2RML implementation
testcases
23

24. 3. Ontology-based
sensor query rewriting
In other words, what happens if our data sources are
not static, but data streams. Can we still use similar
techniques?
24

25. An example: SmartCities
Environmental sensors
Parking sensors
SmartSantander Project
25

26. Data from the Web
Flood risk alert:
South East England
Emergency
I have to make
planner
sense out of all this
data
wave data Environmental
forecasts defenses
Heterogeneity
Continuous querying
Streaming data
26

27. Ingredients for Linked Sensor Data
Core ontological model
Additional domain ontologies
Guidelines for generation of identifiers
Sensor Web programming interfaces
Query processing engines
http://www.flickr.com/photos/santos/2252824606/

28. Overview of the SSN ontology
Deployment deploymentProcesPart only System OperatingRestriction
hasSubsystem only, some hasSurvivalRange only
SurvivalRange
DeploymentRelatedProcess
hasDeployment only
System
OperatingRange
Deployment deployedSystem only hasOperatingRange only
deployedOnPlatform only Process
inDeployment only Device hasInput only
Input
PlatformSite onPlatform only Device Process
Platform Output
attachedSystem only hasOutput only, some
Data Skeleton
isProducedBy some implements some
Sensor
Sensing
hasValue some sensingMethodUsed only
SensorOutput
detects only
SensingDevice observes only
ObservationValue SensorInput
isProxyFor only
Property
includesEvent some isPropertyOf some
observedProperty only
observationResult only
observedBy only hasProperty only, some
Observation FeatureOfInterest
featureOfInterest only
MeasuringCapability ConstraintBlock
hasMeasurementCapability only forProperty only
inCondition only inCondition only
MeasurementCapability Condition
Compton M, Barnaghi P, Bermúdez L, García-Castro R, Corcho O, Cox S, Graybeal J, Hauswirth M, Henson C, Herzog A,
Huang V, Janowicz K, Kelsey WD, Le Phuoc D, Lefort L, Leggieri M, Neuhaus H, Nikolov A, Page K, Passant A, Sheth A,
Taylor K. The SSN Ontology of the W3C Semantic Sensor Network Incubator Group. Journal of Web Semantics. In press

29. SSN Ontology with other Ontologies
García-Castro R, Corcho O, Hill C. A Core Ontology Model for Semantic Sensor Web Infrastructures.
International Journal of Semantic Web and Information Systems 8(1):22-42
29

30. Queries to Sensor Data
SNEEql
RSTREAM SELECT id, speed, direction FROM wind [NOW];
Data Stream Mgmt System
Esper QL
SELECT wind_speed FROM wind_sensor.win:time(10 min)
Complex Event Processors
GSN RESTful service
http://montblanc.slf.ch:22001/multidata?vs[0]=wind_sensor&field[0]=wind_speed&
from=15/09/2011+05:00:00&to=15/09/2011+15:00:00
Pachube RESTful service
http://api.pachube.com/v2/feeds/14321/datastreams/4?start=2011-09-
02T14:01:46Z&end=2011-09-02T17:01:46Z
Sensor Data Middleware
Querying through ontologies?
30

31. SPARQL-Stream
SELECT ?windspeed ?tidespeed
FROM NAMED STREAM <http://swiss-experiment.ch/data#WannengratSensors.srdf>
[NOW-10 MINUTES TO NOW-0 MINUTES]
WHERE {
?WaveObs a ssn:Observation;
ssn:observationResult ?windspeed;
ssn:observedProperty sweetSpeed:WindSpeed.
?TideObs a ssn:Observation;
ssn:observationResult ?tidespeed;
ssn:observedProperty sweetSpeed:TideSpeed.
FILTER (?tidespeed<?windspeed)}
Query processing closer to data
Use ontologies as conceptual model
Query virtual stream graphs
31

32. SPARQL-Stream
SELECT ?name ( AVG(?temperature) AS ?avgTemperature )
( AVG(?humidity) AS ?avgHumidity )
FROM NAMED STREAM <http://www.cwi.nl/SRBench/observations> [NOW - 1 HOURS SLIDE 1 HOURS]
FROM <http://www.cwi.nl/SRBench/sensors>
FROM <http://www.cwi.nl/SRBench/geonames>
WHERE {
?sensor om-owl:generatedObservation ?temperatureObservation;
Aggregates
om-owl:generatedObservation ?humidityObservation;
Static & Streaming
om-owl:hasLocatedNearRel [ om-owl:hasLocation ?nearbyLocation ] .
?temperatureObservation om-owl:observedProperty weather:_AirTemperature ;
om-owl:result [ om-owl:floatValue ?temperature ] .
?humidityObservation om-owl:observedProperty weather:_RelativeHumidity ;
{ SELECT ?name
om-owl:result [ om-owl:floatValue ?humidity ] .
Windows
WHERE {
Filters, Functions
?nearbyLocation gn:featureClass ?featureClass ;
gn:name | gn:officialName ?name ;
gn:population ?population .
FILTER ( ?population > 15000 && REGEX(?featureClass, “P” , “i") )
}
}
UNION
{ SELECT ?name
WHERE {
Disclaimer: some features NYI
?nearbyLocation gn:parentFeature+ ?parentFeature .
?parentFeature gn:featureClass ?parentClass ;
gn:name | gn:officialName ?name ;
gn:population ?parentPopulation .
FILTER ( ?parentPopulation > 15000 && REGEX(?parentClass, “P” , “i") )
}
}} GROUP BY ?name
32

33. Querying the Observations
SELECT ?waveheight
FROM STREAM <www.ssg4env.eu/SensorReadings.srdf>
[NOW -10 MINUTES TO NOW STEP 1 MINUTE]
WHERE {
?WaveObs a sea:WaveHeightObservation;
sea:hasValue ?waveheight; }
http://montblanc.slf.ch :22001/ multidata ?vs [0]= wan7 &
field [0]= sp_wind
Query
:Wan4WindSpeed a rr:TriplesMapClass;
rr:tableName "wan7"; Rewriting GSN
SPARQLStream
rr:subjectMap [ rr:template
API
"http://swissex.ch/ns#WindSpeed/Wan7/
{timed}";
Mappings
rr:class ssn:ObservationValue;
Query
rr:graph ssg:swissexsnow.srdf ]; Processing
rr:predicateObjectMap [ Sensor
Client
rr:predicateMap [ rr:predicate Network
ssn:hasQuantityValue ];
rr:objectMap[ rr:column "sp_wind" ] ];
Data [tuples]
[triples] translation
R2RML Query processing
Mappings
engines
33

34. Rewriting to different technologies
SELECT ?windspeed
FROM NAMED STREAM <http://swiss-
experiment.ch/data#WannengratSensors.srdf>
[NOW-10 MINUTE TO NOW-0 MINUTE]
WHERE { Query
?WaveObs a ssn:Observation; Rewriting
ssn:observationResult ?windspeed;
Algebra
ssn:observedProperty sweetSpeed:WindSpeed.
} representation
SELECT wind_speed_scalar_av, timed FROM wan7.win:time(10
min)
Esper (CEP)
SELECT wan7.wind_speed_scalar_av AS windspeed, wan7.timed AS
windts FROM wan7[FROM NOW-10 MINUTES TO NOW]
SNEE (DSMS)
http://montblanc.slf.ch:22001/multidata?vs[0]=wan7&
field[0]=wind_speed_scalar_av&
from=15/05/2011+05:00:00&to=15/05/2011+15:00:00 GSN (Middleware)
http://api.pachube.com/v2/feeds/14321/datastreams/4?start=2011-09-
02T14:01:46Z&end=2011-09-02T17:01:46Z Pachube (Middleware)
Calbimonte JP, Corcho O, Yeung H, Aberer K. Enabling Query Technologies for the Semantic Sensor Web.
International Journal of Semantic Web and Information Systems 8(1):43-63
34

35. Ongoing work
• Benchmarking of ontology-based streaming data
engines
• Zhang Y, Pham MD, Corcho O, Calbimonte JP. SRBench: A
Streaming RDF/SPARQL Benchmark. Proceedings of the
11th International Semantic Web Conference (ISWC2012)
• Improve optimisations when joining static and
streaming data
• Automatic characterisation of sensor data streams
• Useful in citizen science approaches (e.g., AirQualityEgg)
• Calbimonte JP, Yan Z, Jeung H, Corcho O, Aberer K.
Deriving Semantic Sensor Metadata from Raw
Measurements. ISWC2012 5th International Workshop on
Semantic Sensor Networks 2011 (SSN2012). CEUR
Workshop Proceedings, Vol-904, http://ceur-ws.org/Vol-904/
35

36. 4. Federated query
processing
In other words, how can we access data from federated
data sources
36

37. Example
• We query the life science domain
1. Using the Pubmed references obtained from the GeneID
gene dataset, retrieve information about genes and their
references in the Pubmed dataset.
2. From Pubmed we access the information in the National
Library of Medicines controlled vocabulary thesaurus,
stored at the MeSH endpoint, so we have more complete
information about such genes.
3. Finally, we also access the HHPID endpoint, which is the
knowledge base for the HIV-1 protein.
37

38. Introduction
• Question:
• How can we access such amount of RDF data in an
integrated manner?
• Current approaches
• Replicate data in local stores, access it using existing RDF
databases.
• Execute individual queries and manually join data.
• Use existing distributed query systems (starting to appear).
38

39. Problem
• Existing tools for distributed SPARQL query
processing differ in the way of handling distribution
• SPARQL-published the Federated Query Document Last
Call Working Draft
• It homogenises the access to distributed RDF data
repositories
• SERVICE <http://dbpedia.org/sparql> {...}
• Problems in semantics: SERVICE ?X not well defined
• Current Access to SPARQL endpoints is not optimal
• Work on SPARQL distributed query optimization is beginning
39

40. State of the Art
• ANAPSID, RDF::Query, OpenAnzo, ARQ, Rasqal
RDF Query Library
• ANAPSID provides SPARQL optimization based on
adaptive query processing operators
• RDF::Query provides basic pattern reordering
• Implement the federation using query
predicates
• List of SPARQL endpoints needed
• Helps user to direct queries to
remote datasets
• FedX, SPLENDID, SemWIQ,
NetworkedGraphs
• All provide basic optimisations: pattern
grouping (FedX), cost based
optimizations(SemWIQ, SPLENDID and
recently FedX, NetworkedGraphs)
• SPARQL 1.1 is mostly syntactic sugar
40

41. Assumptions & Restrictions
• Assumptions
1. Users know how to create a
query to the endpoints
2. No statistics of any kind are
available for the query
processing system.
3. Data are distributed
• Restrictions
1. We only consider the
Federation Extension of
SPARQL 1.1
2. We are not aware of the
capabilities or implementation
of the remote SPARQL server
3. No registry of endpoints
41

42. SERVICE Semantics
Example:
SELECT ?name ?email SELECT ?name ?email
WHERE { WHERE {
?y :name ?name . SERVICE <http://example1.org/sparql>
?y :email ?email {?y :name ?name} .
} SERVICE <http://example2.org/sparql>
{?y :email ?email}
}
• We extend [PAG09] with the semantics for SERVICE:
42

43. SERVICE Semantics
Example:
SELECT ?name
WHERE {
SERVICE ?X {?y :name ?name}
}
43

44. SPARQL Optimisation - OPTIONAL
• We assume that we have no statistics of endpoints
• This means that we cannot use cost-based optimisations
• We will only focus on static optimisations
• Besides the usual static optimisations (e.g. Pushing
down filters) SPARQL queries can be optimised if
they contain OPTIONAL operators
• The OPTIONAL operator is responsible for PSPACE-
completeness in SPARQL [PAG09]
• OPTIONAL is a key operator in SPARQL
44

45. Well-designed patterns
• Well-designed SPARQL patterns [PAG09]
• Class of SPARQL patterns which adds a restriction
45

46. Well-designed Patterns
• We extended the notion of well-designed patterns for
the SPARQL 1.1 Federation Extension
• The previous rules also hold for SERVICE
46

47. Implementation: SPARQL-DQP
• SPARQL-DQP is implemented on top of OGSA-DAI and OGSA-
DQP
• OGSA-DAI is a Web service-based framework for accessing
distributed data resources
• OGSA-DQP adds distributed query processing infrastructure
• We reuse some OGSA-DQP operators
• We added RDF and SPARQL endpoint data access
• RDFB2RDF data resource
• RDF data resource
• SPARQL endpoint resources
• Good behaviour for large
datasets
Buil C, Arenas M, Corcho O. Semantics and
optimization of the SPARQL 1.1 federation
extension. Proceedings of the 8th Extended
Semantic Web Conference (ESWC2011).
Springer-Verlag LNCS 6644, pages 1-15
47

48. Ongoing Work
• An extensive benchmark has been produced
• Montoya G, Vidal ME, Corcho O, Ruckhaus E, Buil-Aranda
C. Benchmarking Federated SPARQL Query Engines: Are
Existing Testbeds Enough? In: Proceedings of the 11th
International Semantic Web Conference (ISWC2012)
• Focusing now on Adaptive Query Processing
• Query Processing should be adapted to the user's specific
needs and specific network requirements
48

49. 5. Entailment in query
rewriting
In other words, how can we take into account the
existence of ontologies in the query rewriting process,
so as to provide simple entailment
49

50. Main approaches in the state of the art
Expressiveness Author System Output
[R] Datalog,
ELHIO¬ Pérez-Urbina et al. REQUIEM
UCQ
Sticky-join [linear] datalog± Gottlob et al. Nyaya UCQ
DL-LiteR, DL-LiteF Calvanese et al. QuOnto UCQ
DL-LiteR Chortaras et al. Rapid UCQ
Presto & NR-Datalog &
DL-LiteR [+EBox] Rosati et al.
Prexto UCQ
50

51. Optimizations in the rewriting
• The rewriting can be optimized in
several ways
• Ontology preprocessing
• Subsumption checks
• Prioritize inferences
• Constrain the searches
51

52. Our proposal
José Mora 52

53. Conclusion and Future Work
• We have proposed some small incremental
improvements over the current state of the art in
entailment-aware query rewriting
• Need to integrate it with the rest of our work
• This will happen during Fall 2012
53

54. Final conclusions and
future work
54

55. Ingredients
100
80 thin applications (mas hups )
middleware
60 5 Reasoning Este
40
s emantic data integration and querying
Oeste
20 1 RDB2RDF
Norte
0
1er 3er 3 legacy
Sensor-based
2 query rewriting
Optimisations
data s ources
trim. regis tries
s ens or networks trim.
Federated Query
4 Processing
Linked Open Data Spreadsheets
55

56. Data integration at our group:
ingredients and some
prospects
Credible workshop
Sophia-Antipolis, October 15th 2012
Oscar Corcho
ocorcho@fi.upm.es
Facultad de Informática, Universidad Politécnica de Madrid
Campus de Montegancedo s/n. 28660 Boadilla del Monte, Madrid, Spain
With contributions from: José Mora (OEG-UPM), Boris Villazón-Terrazas (OEG-UPM, now at
iSOCO), Jean Paul Calbimonte (OEG-UPM), Freddy Priyatna (OEG-UPM), Carlos Buil-Aranda
(OEG-UPM, now at PUC Chile)