Dietze Aswc 2009 Final

Two-Fold Service Matchmaking –
Applying Ontology Mapping for Semantic Web
Service Discovery

/// ASWC’09, Shanghai, China, December 08, 2009

Stefan Dietze1, Neil Benn1, John Domingue1, Alex Conconi2, Fabio Cattatoni2
1Knowledge Media Institute, The Open University, UK
2TXT eSolutions, Italy

Outline

Semantic Web Services (SWS) mediation

Two-fold matchmaking approach for SWS

Prototypical implementation & application

Conclusions

08/12/2009 4th Asian Semantic Web Conference

Introduction
Semantic Web Services (SWS)

Formalisations of Web services in
terms of capabilities (Cap),
interfaces (If) and non-functional
properties (Nfp)

Capabilities: assumptions (Ass) and
effects (Eff)

sws:WebService sws:WebService sws:WebService
Use ontologies O (i.e. tuple of SWS.1 SWS.2 SWS.3
concepts C, instances I, properties
P, relations R and axioms A)

Reference models e.g. OWL-S,
WSMO, SAWSDL
WebService WebService WebService
WS.1 WS.2 WS.3


SWS matchmaking
Issues

SWS discovery: matchmaking of
capabilities of SWS e.g. : sws:Request
R.1
As 2 ⊂ As1 ∪ Ef 2 ⊂ Ef1

? ?

SWS.1 SWS.2 SWS.3

WS.1 WS.2 WS.3


SWS matchmaking
Issues

As1 ≡ ¬ I1 ∩ I 2
SWS discovery: matchmaking of has-assumption

R.1
As 2 ⊂ As1 ∪ Ef 2 ⊂ Ef1

I.e., matching logical expressions

SWS.1 SWS.2 SWS.3

has-assumption

As 2 ≡ I 3 ∩ ¬ I 4

WS.1 WS.2 WS.3


SWS matchmaking
Issues
<geospatialLocation rdf:ID="M-K"/>

As1 ≡ ¬ I1 ∩ I 2
SWS discovery: matchmaking of has-assumption

R.1
As 2 ⊂ As1 ∪ Ef 2 ⊂ Ef1
?
I.e., matching logical expressions…
…which are heterogeneous.
SWS.1 SWS.2 SWS.3

has-assumption

As 2 ≡ I 3 ∩ ¬ I 4

<Location rdf:ID="Milton_Keynes"/>
WS.1 WS.2 WS.3


SWS matchmaking
Semantic-level mediation

SWS discovery: matchmaking of
R.1
As 2 ⊂ As1 ∪ Ef 2 ⊂ Ef1

Semantic-Level Mediation
I.e., matching logical expressions…
…which are heterogeneous.
SWS.1 SWS.2 SWS.3

Requires: mediation between
concepts/instances across
Mediation between heterogeneous
heterogeneous SWS.
semantic representations
WS.1 WS.2 WS.3


SWS matchmaking
Two-fold process

Proposal:
SWS matchmaking as two-fold process
(i) Semantic mediation via ontology (instance) mapping
(ii) Logical reasoning for matchmaking of capability/interface descriptions


SWS matchmaking
Two-fold process

Proposal:
SWS matchmaking as two-fold process
(i) Semantic mediation via ontology (instance) mapping
(ii) Logical reasoning for matchmaking of capability/interface descriptions

Issues:
Traditional SWS matchmaking focusses on (ii)
Integration of (i):
Via manual mappings? - costly
Via exploitation of linguistic or structural similarities? - prone to errors
Representations allowing for implicit similarity-computation ?


Approach: instance similarity computation in shared MS

Refining SWS ontologies through multiple “Mediation Spaces” (MS), i.e. multidimensional,
{
vector spaces MS n = ( p1d1, p2d2 ,..., pndn ) di ∈ MS, pi ∈ ℜ }
Through MS ontology (extends SWS descriptions)

Concept C in SWS ontology O => Mediation Space MS / Instance I of C => member M
(vector) in MS

SWS Ontology O1
Concept C1x
instance-of instance-of

refined-as-ns
Instance I1i Instance I1j

d1
refined-as-member refined-as-member

d2
d3

Mediation Space MS1x


Approach: instance similarity computation in shared MS

Similarity-computation between SWS instances => spatial distances in MS
n
ui − u v −v 2
e.g. Euclidean distance: dist (u, v) = ∑ p ((
i =1
i
su
)−( i
sv
))

Common agreement at schema (i.e. MS) level

Agent 1 Agent 2
SWS Ontology O1 SWS Ontology O2
Concept c1x Concept c2x

instance-of instance-of
refined-as-ms refined-as-ms

Instance i1i Instance i2i

refined-as-member d1 refined-as-member

d2
d3

Mediation Space MSx


Similarity-based service matchmaking
Implementation based on WSMO/IRS-III

Implementation: Web Service Modelling Ontology (WSMO) & SWS environment IRS-III

wsmo:Goal
G.1
(1)
(2)
wsmo:Mediator wsmo:MedWS
Med.1 SWS.1.1 Comp. Sim.
(3)
(4)

wsmo:WebService wsmo:WebService wsmo:WebService
SWS.1 SWS.2 SWS.3
(5)


Similarity-based service matchmaking
Implementation based on WSMO/IRS-III

Implementation: Web Service Modelling Ontology (WSMO) & SWS environment IRS-III

WSMO Mediator: computation of similarities between given request (WSMO Goal, G1) and
−1
set of x associated SWS (SWS1..SWSx):  n 
 ∑ ( dist k ) 
Sim(Gi , SWS j ) = Dist (Gi , SWS j ) =  k =1
( ) 
−1

 n 
 
 
Limitation: suitability of service computed based on instance similarities
(=> current work: integration into “real” two-fold matchmaking)

wsmo:Goal
G.1
(1)
(2)
wsmo:Mediator wsmo:MedWS
Med.1 SWS.1.1 Comp. Sim.
(3)
(4)

wsmo:WebService wsmo:WebService wsmo:WebService
SWS.1 SWS.2 SWS.3
(5)


Semantic mediation through MS
Prototypical application

Uses representational approach (MS, similarity-based WSMO Mediator)

Retrieval of distributed video resources
(provided within EU FP7 IP NoTube - http://notube.tv)

Keyword-based searches across Web services exposing video repositories

BBC Backstage (news feed) [ http://backstage.bbc.co.uk/ ]

BBC Programmes RDF [ http://api.talis.com/stores/bbc-backstage ]

Open Video [ http://www.open-video.org/ ]

OU channel on YouTube [ http://www.youtube.com/ou ]

YouTube (mobile feed) [ http://www.youtube.com/ou ]

Similarity-based service discovery for given request



SWS6:
get-video-request
M6 ={v1, v2, v3} M6 ={v1, v2}
1 2

MS1 Purpose Space MS2 Environment Space

O1:Purp O1:Env O2:Purp O2:Env O3:Purp O3:Env O4:Purp O4:Env O5:Purp O5:Env
SWS1: SWS2: SWS3: SWS4: SWS5:
OU-youtube bbc-programmes open-video bbc-backstage mobile-youtube

WS1: WS2: WS3: WS4: WS5:



SWS6:
get-video-request
M6 ={v1, v2, v3} M6 ={v1, v2}
1 2

{(p1*information, p2*education, p3*leisure)} = CS1 {(p4*resolution, p5*bandwidth)} = CS2






SWS6:
get-video-request
M6 ={v1, v2, v3} M6 ={v1, v2}
1 2


Requests (WSMO Goals) via AJAX-based UI
Consist of:
SWS : SWS2: SWS3: SWS4: SWS5:
1
OU-youtube entertain-youtube open-video bbc-backstage mobile-youtube
Input parameters: set of keywords
Assumption: defined through dynamically created instances
WS :
1 2WS : 3 WS :
4 WS : WS5:
OU-youtube on measurements describing purpose and environment)
(based entertain-youtube open-video bbc-backstage mobile-youtube
Similarity-based SWS discovery based on WSMO mediator


Demo

SWS6:
get-video-request
M6 ={v1, v2, v3} M6 ={v1, v2}
1 2





Conclusions
Summary & discussion

Summary:

Two-fold approach: considering semantic-level mediation as implicit element of SWS
matchmaking

Mediation approach based on (instance) similarity-computation

Issues:

Matchmaking purely based on instance similarities
(=> current work: integration into “real” two-fold matchmaking)

Similarity-calculation requires overlapping MS and measurable quality dimensions

Additional representational effort => future work: evaluation


Thank you!

E-mail: s.dietze@open.ac.uk
Web: http://people.kmi.open.ac.uk/dietze


Dietze Aswc 2009 Final

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