Ontology-enhanced Semantic Ontology-enhanced Semantic Request and Response (OSRR) - Request and Response (OSRR) -

The New Paradigm for Geospatial The New Paradigm for Geospatial Semantic Web ServicesSemantic Web Services

Xuan ShiXuan ShiWest Virginia UniversityWest Virginia UniversityXuan.Shi@mail.wvu.edu

OverviewOverview

Web services – problems in the old Web services – problems in the old paradigmparadigm

Semantic Web services – goals and Semantic Web services – goals and chaoschaos

OSRR – an alternative solution and OSRR – an alternative solution and challengechallenge

Semantic Interoperability – consensus Semantic Interoperability – consensus vs. logicsvs. logics

Web services Web services

Ambiguity in definitionAmbiguity in definition– Web service may Web service may NOTNOT have any relation have any relation

with the Web.with the Web. Web service is the solution of software Web service is the solution of software

interoperability, taking the places of interoperability, taking the places of CORBA and DCOMCORBA and DCOM– A service is a functional component of the A service is a functional component of the

software package, accessible through software package, accessible through programming interface (API)programming interface (API)

(Web) service is (Web) service is notnot a Web site, or Web- a Web site, or Web-related.related.

Problems with Web services Problems with Web services

Desktop Desktop GISGIS

Geographers, and other scientists and Geographers, and other scientists and engineers who are not engineers who are not programmersprogrammers, , cannot usecannot use Web services even if they can Web services even if they can find the required services that are only find the required services that are only accessible through APIsaccessible through APIs

Web Services Description Language Web Services Description Language (WSDL) defines the programming (WSDL) defines the programming interface at the syntactic level, not interface at the syntactic level, not semantic – even semantic – even programmersprogrammers cannot cannot understandunderstand the meaning of the service the meaning of the service

Problems with Web services Problems with Web services

Semantic Web servicesSemantic Web services GoalGoal – enable the dynamic and – enable the dynamic and

automatic service discovery, automatic service discovery, matchmaking, composition and matchmaking, composition and invocationinvocation

Semantic Web servicesSemantic Web services

ChaosChaos – – service registry died !service registry died ! SAWSDL – targets service interfaceSAWSDL – targets service interface OWL-S/WSMO – assumption-based, target OWL-S/WSMO – assumption-based, target

Web siteWeb site related activities related activities Dynamic invocation has been ignoredDynamic invocation has been ignored

SAWSDLSAWSDL Add semantic annotation onto WSDL elementsAdd semantic annotation onto WSDL elements

matchType: a subclass of string. matchType: a subclass of string. • What does matchType mean if the value = “A”What does matchType mean if the value = “A”

matchType: a subclass of hex code. matchType: a subclass of hex code. • If the value = “A”, matchType means “10” !If the value = “A”, matchType means “10” !

Hex numbers use 16 digits:Hex numbers use 16 digits:

0 1 2 3 4 5 6 7 8 9 A B C D E F0 1 2 3 4 5 6 7 8 9 A B C D E F

What should I do if matchType = “A” ?!What should I do if matchType = “A” ?!

OWL-S/WSMOOWL-S/WSMO

Virtual Travel Agency (VTA) use case of service aggregation/mediation(Modified from Semantic Web Services Tutorial authored by Stollberg, et al. 2005)

ServiceRequester

ServiceSemantics

ServiceProvider

ServiceEnd Users

- Supposed semantic Web is available (- Supposed semantic Web is available (not truenot true))- Supposed the required services can be discovered (- Supposed the required services can be discovered (not truenot true – no service registry) – no service registry)- Supposed the discovered services have a feature of "exact match" to those - Supposed the discovered services have a feature of "exact match" to those proprietary ontology definitions (since same services may have different APIs and proprietary ontology definitions (since same services may have different APIs and WSDLs, discovered services may be WSDLs, discovered services may be similarsimilar or or relatedrelated to each other) to each other)But even OWL-S is not compatible with WSMO, let alone any solution to the But even OWL-S is not compatible with WSMO, let alone any solution to the semantic interoperability.semantic interoperability.

Dynamic service invocationDynamic service invocation

The dynamic invocation of Web services is The dynamic invocation of Web services is envisioned as “envisioned as “without any reprogramming, a without any reprogramming, a software system could have the flexibility to use software system could have the flexibility to use various services that do the same kind of job but various services that do the same kind of job but have different APIshave different APIs” (Burstein, 2004)” (Burstein, 2004)

Such a statement means that: Such a statement means that: – Service semantics (what services do) are not the Service semantics (what services do) are not the

same as service interfaces. same as service interfaces. – Service semantics can be the same (do the same job) Service semantics can be the same (do the same job)

but the service interfaces are different. but the service interfaces are different.

Standardized APIs for ALL Standardized APIs for ALL Kinds of Services:Kinds of Services:

FFunction getService(String request): String responseunction getService(String request): String response

Input: a1, a2, x2, x3, y1, y3Output: z1, z2, z3

Input: x1, x2, y1Output: m1, m2

Input: x1, x2, y1, y2Output: z3

Semantic Request and Response Semantic Request and Response

Geographers, and other scientists and engineers who Geographers, and other scientists and engineers who are not are not programmersprogrammers, can use Web services through , can use Web services through SRR when they can find the required servicesSRR when they can find the required services

Reverse EngineeringReverse EngineeringFor a ReconstructionFor a Reconstruction

OSRR – “O” for Service OSRR – “O” for Service Discovery and MatchmakingDiscovery and Matchmaking

Semantics of Web servicesSemantics of Web services– What are the Web services and what What are the Web services and what

functions do they offer? functions do they offer? – How does the service requester send the How does the service requester send the

request to deploy the service and function? request to deploy the service and function? – What service output result can the What service output result can the

requester expect after the invocation?requester expect after the invocation?

Five building blocks in OSRRFive building blocks in OSRR1.1. Service domain and function category Service domain and function category

descriptiondescription2.2. Format of the service request input XML Format of the service request input XML

documentdocument3.3. Format of the service response output Format of the service response output

XML documentXML document4.4. Service request input requirements: Service request input requirements:

defines the template for service requestdefines the template for service request5.5. Service response output prototype: Service response output prototype:

defines the template for service response.defines the template for service response.

OSRR – “O” for Service OSRR – “O” for Service Discovery and MatchmakingDiscovery and Matchmaking

Semantic InteroperabilitySemantic Interoperability

Ontology could be described as a Ontology could be described as a formalizedformalized and and sharedshared specification of a specification of a commoncommon conceptualization of a domain knowledge conceptualization of a domain knowledge (Gruber, 1993; Uschold, (Gruber, 1993; Uschold, et al.,et al., 1996), 1996),

The word “semantic” represents the meaning The word “semantic” represents the meaning of. The “semantics” of something is the of. The “semantics” of something is the meaning, or an interpretation of the meaning, meaning, or an interpretation of the meaning, of something. of something.

Semantic AmbiguitySemantic AmbiguityHTML is not HTML is not semantic,semantic, for it is not machine-processable for it is not machine-processable

WSDL is not WSDL is not semantic,semantic, although it is machine-processable although it is machine-processable

VeltmanVeltman (2004) concluded that, “a (2004) concluded that, “a semantic Websemantic Web which which deals only tangentially with meaning might more deals only tangentially with meaning might more accurately be called the accurately be called the transactionstransactions web (EDI redivivus) web (EDI redivivus) or the or the logic weblogic web”. Those who designed semantic Web ”. Those who designed semantic Web consider that,consider that, ““logical meaning is the only objective logical meaning is the only objective dimension of meaning; that all other meaning is subjective dimension of meaning; that all other meaning is subjective and therefore unimportantand therefore unimportant. . In this view, the semantic web In this view, the semantic web rightfully limits itself to the realms of logicrightfully limits itself to the realms of logic. . In science, In science, technology and business this claim leads to pragmatic technology and business this claim leads to pragmatic resultsresults””..

Semantic InteroperabilitySemantic InteroperabilityOntology = <taxonomy, logical inference rules>, and Ontology = <taxonomy, logical inference rules>, and taxonomy can be expressed as Taxonomy = <{classes}, taxonomy can be expressed as Taxonomy = <{classes}, {relations}> (Alesso, 2004). {relations}> (Alesso, 2004).

Semantic InteroperabilitySemantic InteroperabilitySW vs. SWSSW vs. SWS

Concepts defined in Semantic Web are Concepts defined in Semantic Web are meaningfulmeaningful

Terms used in WSDL are Terms used in WSDL are meaninglessmeaningless symbols symbols

<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:foaf="http://xmlns.com/0.1/foaf/" > <rdf:Description rdf:about=""> <dc:creator rdf:parseType="Resource"> <foaf:name>Sean B. Palmer</foaf:name> </dc:creator> <dc:title>The Semantic Web: An Introduction</dc:title> </rdf:Description> </rdf:RDF>

Limitations of RDF/OWLLimitations of RDF/OWL

Limitations of RDF/OWLLimitations of RDF/OWL

- Service - Service aa provide address geocoding service that provide address geocoding service that retrieves the latitude and longitude of an input retrieves the latitude and longitude of an input addressaddress- Service - Service bb provides a service to convert latitude provides a service to convert latitude and longitude into another coordinate pairs with a and longitude into another coordinate pairs with a different projection system such as UTMdifferent projection system such as UTM- Service - Service cc provides a service to directly retrieve provides a service to directly retrieve the UTM x, y coordinates from the input addressthe UTM x, y coordinates from the input address

ServiceService c = a + bc = a + b

RDF/OWL does RDF/OWL does notnot understand: understand: 2 + 3 = 52 + 3 = 5

Semantic Interoperability Semantic Interoperability Consensus vs. Logic ModelingConsensus vs. Logic Modeling

What is the ontology and What is the ontology and semantics of the semantics of the Prime Prime MeridianMeridian??

Is Is Prime MeridianPrime Meridian based on based on consensus or logic modeling? consensus or logic modeling?

Is GML a Is GML a formalizedformalized, , sharedshared specification of aspecification of a commoncommon conceptualization?conceptualization?

““First Class High Way” (USGS) First Class High Way” (USGS) = “Interstate Road” (USDOT)= “Interstate Road” (USDOT)

ModelingModeling Prime Meridian ?Prime Meridian ? Amsterdam, Athens, Bern, Amsterdam, Athens, Bern, Helsinki, Lisbon, New York, Helsinki, Lisbon, New York, Oslo, Peking, Paris, Rome, Oslo, Peking, Paris, Rome, Tokyo, or StockholmTokyo, or Stockholm …? …?

In scientific research, In scientific research, we just need we just need oneone evidence to deny a evidence to deny a hypothesis or theoryhypothesis or theory

Owner a: Polygon A (1,3 3,5 5,3 3,5 1,3)Owner a: Polygon A (1,3 3,5 5,3 3,5 1,3)

Owner b:Owner b: Polygon B (2,5 4,7 6,5 4,3 2,5)Polygon B (2,5 4,7 6,5 4,3 2,5)

Owner c:Owner c: Polygon C (4,4 6,6 8,4 6,2 4,4)Polygon C (4,4 6,6 8,4 6,2 4,4)

Owner d:Owner d: Polygon D (4,5 5,6 7,4 6,3 4,5)Polygon D (4,5 5,6 7,4 6,3 4,5)

Owner e:Owner e: Polygon E (2.5,4.5 3,5 4.5,3.5 4,3 2.5,4.5)Polygon E (2.5,4.5 3,5 4.5,3.5 4,3 2.5,4.5)

Semantic Interoperability Semantic Interoperability - - beyond the logical relationshipsbeyond the logical relationships

A touches CA touches C

B touches DB touches D

B intersects AB intersects A

B intersects CB intersects C

C contains DC contains D

D is contained by CD is contained by C

E is the difference of A and BE is the difference of A and B

… … … …

? ? What is the What is the UnionUnion of A and B of A and B ExcludedExcluded by the by the DifferenceDifference of of A and B A and B ??

How to define the How to define the topologicaltopological relation between the geometric relation between the geometric features through features through logical modelinglogical modeling??

AA

BB

CCDD

0,00,0 11

11

22 33 44 55 66 77 88 99 1010

22

33

44

55

66

77

EE

Semantic InteroperabilitySemantic Interoperability

We need more consensus, agreements, standards, not Logic ModelingWe need more consensus, agreements, standards, not Logic Modeling

??

Objective Objective OR OR

Subjective Subjective relationship relationship

among among geometric geometric features?features?

Thank You!Thank You!

Questions?Questions?