This document presents an approach for semantically annotating RESTful web services. The approach involves (1) obtaining syntactic descriptions of services, (2) semantically enriching parameters using ontologies like DBpedia and GeoNames, and (3) checking annotations by executing services. The approach was tested on 60 services, annotating over 1500 parameters total by matching to ontologies or using suggestion/synonym services. Evaluation showed the approach improved recall over initial parameter matches. Future work aims to improve annotation standards and integration.

1. Lightweight Semantic
Annotation of Geospatial
RESTful Services
Victor Saquicela, Luis. M. Vilches-Blazquez, and Oscar Corcho
Facultad de Informática, Universidad Politécnica de Madrid
Campus de Montegancedo s/n, 28660 Boadilla del Monte, Madrid
http://www.oeg-upm.net
{vsaquicela,lmvilches,ocorcho}@fi.upm.es
Phone: 34.91.3366605, Fax: 34.91.3524819
Presented by Boris Villazón-Terrazas
Project: EV
ESWC 2011
Date: 02/06/2011
Heraklion, Greece

2. ToC
• Introduction & motivation
• Related work
• Semantic annotation of RESTful services
• A sample set of RESTful services
• Syntactic description
y
p
• Semantic annotation
• Checking the semantic annotation of RESTful services
Checking the semantic annotation of RESTful
• Experimental results
• Conclusions and future work
2

3. Introduction and motivation
RESTful
Service X
RESTful
Service Y
RESTful
Service
S i W
RESTful
Service W
•
Description in HTML that contains:
• a list of the available operations
• URIs and parameters
• expected output
• error messages
• set of examples of execution
3274 of RESTful services (APIs) in programmableweb.com
RESTful
Service Z
…

4. Introduction
•
Description in HTML page
4

5. Related work
• Syntactic
• H
Heavyweight: WSDL
i ht
• Lightweight: WADL, hREST
• Semantic
• Heavyweight: OWL-S, WSMO
y
g
• Lightweight: SA-REST, MicroWSMO
• Tools
• SWEET
• WSMO editor
5

6. Our approach
Semantic annotation of RESTf l services b
S
ti
t ti
f RESTful
i
by
(1) Obtaining and formalising their syntactic descriptions
(2) Interpreting, and semantically enriching their parameters
Our approach uses diverse types of resources
•
cross-domain ontology, DBpedia (combined with GeoNames)
•
Suggestion services
•
Synonym services
Semantic
annotation
Repository
Syntactic description
6

7. A sample set of RESTful services
•
•
Service 1. retrieves information related to a country.
• http://ws.geonames.org/countryInfo?country=ES
Service 2. retrieves information about places (venues).
• htt // i
http://api.eventful.com/rest/venues/search?app_key=p4t8BFcLDt C
tf l
/ t/
/
h?
k
4t8BF LDt CzpxdS&location=Madrid
dS&l
ti
M d id
Service 1
Service 2
<geonames>
<country>
y
<countryCode>ES</countryCode>
<countryName>Spain</countryName>
<isoNumeric>724</isoNumeric>
<isoAlpha3>ESP</isoAlpha3>
<fipsCode>SP</fipsCode>
<continent>EU</continent>
<capital>Madrid</capital>
<areaInSqKm>504782.0</areaInSqKm>
<population>40491000</population>
<currencyCode>EUR</currencyCode>
C d EUR /
C d
<languages>es-ES,ca,gl,eu</languages>
<geonameId>2510769</geonameId>
<bBoxWest>-18.169641494751</bBoxWest
<bBoxNorth>43.791725</bBoxNorth>
<bBoxEast>4.3153896</bBoxEast>
<bBoxSouth>27.6388</bBoxSouth>
</country>
</geonames>
7
<venue id="V0-001-000154997-6">
<url>http://eventful.com/madrid/venues/laancha-/V0-001-000154997-6</url>
<country_name>Spain</country_name>
<name>La Ancha</name>
<venue_name>La Ancha</venue_name>
<description></description>
<venue_type>Restaurant</venue_type>
<address></address>
<city_name>Madrid</city_name>
<region_name></region_name>
<region_abbr></region_abbr>
<postal_code></postal_code>
<country_abbr2>ES</country_abbr2>
<country_abbr>ESP</country_abbr>
<longitude>-3.68333</longitude>
<latitude>40.4</latitude>
<geocode_type>City Based GeoCodes
</geocode_type>
<owner>frankg</owner>
owner frankg /owner
<timezone></timezone>
<created></created>
<event_count>0</event_count>
<trackback_count>0</trackback_count>
<comment_count>0</comment_count>
<link_count>0</link_count>
<li k
t>0</li k
t>
<image></image>
</venue>
<venue id="V0-001-000154998-5">

8. Syntactic description: Invocation and registration
• User adds the URL of a service in our system
y
• System invokes the RESTful service with some sample
parameters, by using SDO API
• System analyzes the response (XML) to obtain a syntactic
description of the parameters
• Results
•
•
Service1.
countryInfo($country,bBoxSouth,isoNumeric,continent,fipsCode,areaInSqK
m,languages,isoAlpha3,countryCode,bBoxNorth,population,bBoxWest,curre
ncyCode,bBoxEast,capital,geonameId,countryName)
ncyCode bBoxEast capital geonameId countryName)
Service2.
rest/venues/search($location,$app_key,id,link_count,page_count,longitude,t
rackback_count,version,venue_type,owner,url,country_name,event_count,t
rackback count,version,venue type,owner,url,country name,event count,t
otal_items,city_name,address,name,latitude,page_number,postal_code,cou
ntry_abbr,first_item,page_items,last_item,page_size,country_abbr2,comme
nt_count,geocode_type,search_time,venue_name)
• Results are stored and WADL file is generated.
8

9. Semantic annotation (I)
• The starting point is the list of syntactic parameters
• Th system retrieves all th classes/properties f
The
t
ti
ll the l
/
ti from
DBpedia ontology whose names have a match with each
p
parameter of the RESTFul Service.
• Exact match
• Similarity measures: Jaro, Jaro Winkler, and Levenshtein
• If the system obtains correspondences from the matching
process,
process it uses DBPedia concepts/properties to retrieve
samples (RDF instances).
• If there is no “matching”, we use external services
• Spelling suggestion services
• Synonym services
9

10. Semantic annotation: example
Service1.
countryInfo($country,bBoxSouth,isoNumeric,continent,fipsCode,areaInSqKm,languages,
isoAlpha3,countryCode,bBoxNorth,population,bBoxWest,currencyCode,bBoxEast,capital,
geonameId,countryName)
geonameId countryName)
Enriching the original parameters with external resources
10

11. Semantic annotation: more examples
11

12. Result
Service1 (i1, i2, o1, o2, o3, o4, o5, o6, o7)
Service 1
(http://dbpedia.org/ontology/Country,http,http://www.w3.org/2003/01/geo/wgs84_pos#lat,http://ww
w.w3.org/2003/01/geo/wgs84_pos#long,isoNumeric,http://dbpedia.org/ontology/Continent,fipsCod
e,http://dbpedia.org/property/areaMetroKm,languages,isoAlpha3,http://dbpedia.org/ontology/countr
y,http://www.w3.org/2003/01/geo/wgs84_pos#lat,http://www.w3.org/2003/01/geo/wgs84_pos#long,
http://dbpedia.org/ontology/populationDensity,http://www.w3.org/2003/01/geo/wgs84_pos#lat,http://
www.w3.org/2003/01/geo/wgs84_pos#long,http://dbpedia.org/ontology/Currency,http://www.w3.org
/2003/01/geo/wgs84_pos#lat,http://www.w3.org/2003/01/geo/wgs84_pos#long,http://dbpedia.org/on
tology/capital,geonameId,http://dbpedia.org/ontology/country)
12

13. Checking the semantic annotation (Input)
• The system selects for each parameter a random subset
of the example instances.
• It makes several invocations of the service, by iterating
over the registered values.
g
• If the service return results from the invocation -> the
service is considered as executable; non-executable if it
cannot invoked succesfully.
Country
http://dbpedia.org/ontology/country
Instance1
Instance2
Instance3
.........
InstanceM
http://dbpedia.org/ontology/locationCountry
Instance1
Instance2
Instance3
.........
InstanceM
13

14. Checking the semantic annotation (Output)
• The system only takes into account executions with
correct inputs.
• The system compares the outputs obtained after
execution with the information already stored in the
y
repository.
• If the output can be matched, the system considers the
output annotations as valid.
• Finally, the correspondences between the different
parameters of the service and DBpedia/Geonames
ontology are registered and stored into the respository.
14

15. Experimental results (I)
•
60 RESTful services selected from www.programmableweb.com (manually)
•
56 registered in the system
•
List of 369 different parameters, 52 input parameters and 342 output parameters,
without duplications.
Attributes
Total
Additional
parameters
Matches (DBpedia and
GeoNames ontologies)
Initial parameters
369
-
191
Parameters + Suggestions
426
57
33
Parameters + Synonyms
y
y
1573
1147
126
Parameters + Suggestions + Synonyms
1573
1204
159
15

16. Experimental results (II)
RESTful
Service
Total
parameters
Annotated
parameters
Annotated
parameters
( p
(DBpedia)
)
Annotated
parameters
(
(GeoNames)
)
Special
parameters
Input
parameters
152
78
33
45
73
Output
parameters
862
315
202
113
299
Service
validation
56
4
-
Results of the input and output parameters
RESTful Service
Output
parameters
Found
parameters
475
Not found
parameters
92
Annotated
315
Output parameters metrics
16
Not
annotated
160
Right
parameters
242
Precision
Recall
0.66
0.77

17. Conclusions and future work
•
We have proposed an approach to perform semantic annotation
process of RESTful services, using ontologies (DBpedia and
Geonames) and external resources (suggestions and synonyms).
•
Future work:
•
GUI that will ease the introduction of existing service by users
users.
•
Improving the SPARQL queries
•
More specific domain ontologies in the semantic process
•
Standards generation such as hREST, SA-REST and MicroWSMO
•
Integration with iServe.
17

19. Lightweight Semantic
Annotation of Geospatial
RESTful Services
Victor Saquicela, Luis. M. Vilches-Blazquez, and Oscar Corcho
Facultad de Informática, Universidad Politécnica de Madrid
Campus de Montegancedo sn, 28660 Boadilla del Monte, Madrid
http://www.oeg-upm.net
{vsaquicela,lmvilches,ocorcho}@fi.upm.es
Phone: 34.91.3366605, Fax: 34.91.3524819
Presented by Boris Villazón-Terrazas
Project: EV
ESWC 2011
Date: 02/06/2011
Heraklion, Greece