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Ontology-enhanced Semantic Request and Response (OSRR) - The New Paradigm for Geospatial Semantic Web Services. Xuan Shi West Virginia University Xuan.Shi@mail.wvu.edu. Overview. Web services – problems in the old paradigm Semantic Web services – goals and chaos

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slide1
Ontology-enhanced Semantic Request and Response (OSRR) - The New Paradigm for Geospatial Semantic Web Services

Xuan Shi

West Virginia University

Xuan.Shi@mail.wvu.edu

overview
Overview
  • Web services – problems in the old paradigm
  • Semantic Web services – goals and chaos
  • OSRR – an alternative solution and challenge
  • Semantic Interoperability – consensus vs. logics
problems with web services
Problems with Web services
  • Ambiguity in definition
    • Web service may NOT have any relation with the Web.
  • Web service is the solution of software interoperability, taking the places of CORBA and DCOM
    • A service is a functional component of the software package, accessible through programming interface (API)
  • (Web) service is not a Web site, or Web-related.
problems with web services1
Problems with Web services
  • Geographers, and other scientists and engineers who are not programmers, cannot use Web services even if they can find the required services that are only accessible through APIs
  • Web Services Description Language (WSDL) defines the programming interface at the syntactic level, not semantic – even programmerscannot understand the meaning of the service
semantic web services
Semantic Web services
  • Goal – enable the dynamic and automatic service discovery, matchmaking, composition and invocation
semantic web services1
Semantic Web services
  • Chaos – service registry died !
  • SAWSDL – targets service interface
  • OWL-S/WSMO – assumption-based, target Web site related activities
  • Dynamic invocation has been ignored
sawsdl
SAWSDL
  • matchType: a subclass of string.
    • What does matchType mean if the value = “A”
  • Add semantic annotation onto WSDL elements
  • matchType: a subclass of hex code.
    • If the value = “A”, matchType means “10” !
  • What should I do if matchType = “A” ?!

Hex numbers use 16 digits:

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

owl s wsmo

Service

Semantics

Service

Provider

Service

Requester

Service

End Users

OWL-S/WSMO

Virtual Travel Agency (VTA) use case of service aggregation/mediation

(Modified from Semantic Web Services Tutorial authored by Stollberg, et al. 2005)

- Supposed semantic Web is available (not true)

- Supposed the required services can be discovered (not true – no service registry)

- Supposed the discovered services have a feature of "exact match" to those proprietary ontology definitions (since same services may have different APIs and WSDLs, discovered services may be similar or related to each other)

But even OWL-S is not compatible with WSMO, let alone any solution to the semantic interoperability.

dynamic service invocation
Dynamic service invocation
  • The dynamic invocation of Web services is envisioned as “without any reprogramming, a software system could have the flexibility to use various services that do the same kind of job but have different APIs” (Burstein, 2004)
  • Such a statement means that:
    • Service semantics (what services do) are not the same as service interfaces.
    • Service semantics can be the same (do the same job) but the service interfaces are different.
standardized apis for all kinds of services f unction getservice string request string response
Standardized APIs for ALL Kinds of Services:Function getService(String request): String response

Input: a1, a2, x2, x3, y1, y3

Output: z1, z2, z3

Input: x1, x2, y1

Output: m1, m2

Input: x1, x2, y1, y2

Output: z3

slide14

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

slide15

Reverse Engineering

For a Reconstruction

osrr o for service discovery and matchmaking
OSRR – “O” for Service Discovery and Matchmaking
  • Semantics of Web services
    • What are the Web services and what functions do they offer?
    • How does the service requester send the request to deploy the service and function?
    • What service output result can the requester expect after the invocation?
osrr o for service discovery and matchmaking1
OSRR – “O” for Service Discovery and Matchmaking
  • Five building blocks in OSRR
    • Service domain and function category description
    • Format of the service request input XML document
    • Format of the service response output XML document
    • Service request input requirements: defines the template for service request
    • Service response output prototype: defines the template for service response.
semantic interoperability
Semantic Interoperability

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

Ontology could be described as a formalized and shared specification of a common conceptualization of a domain knowledge (Gruber, 1993; Uschold, et al., 1996),

slide19

Semantic Ambiguity

HTML is not semantic, for it is not machine-processable

WSDL is not semantic, although it is machine-processable

semantic interoperability1
Semantic Interoperability

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

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

slide21

Semantic Interoperability

SW vs. SWS

Concepts defined in Semantic Web are meaningful

<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>

Terms used in WSDL are meaningless symbols

slide23

Limitations of RDF/OWL

RDF/OWL does not understand: 2 + 3 = 5

- Service a provide address geocoding service that retrieves the latitude and longitude of an input address

- Service b provides a service to convert latitude and longitude into another coordinate pairs with a different projection system such as UTM

- Service c provides a service to directly retrieve the UTM x, y coordinates from the input address

Servicec = a + b

semantic interoperability consensus vs logic modeling
Semantic Interoperability Consensus vs. Logic Modeling

What is the ontology and semantics of the Prime Meridian?

Is Prime Meridian based on consensus or logic modeling?

Is GML a formalized, sharedspecification of acommonconceptualization?

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

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

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

semantic interoperability beyond the logical relationships
Semantic Interoperability - beyond the logical relationships

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

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

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

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

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

A touches C

B touches D

B intersects A

B intersects C

C contains D

D is contained by C

E is the difference of A and B

… …

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

? What is the Union of A and B Excluded by the Difference of A and B ?

semantic interoperability2

7

6

B

5

D

C

E

4

3

A

2

1

0,0

1

2

3

4

5

6

7

8

9

10

Semantic Interoperability

Objective OR Subjective relationship among geometric features?

?

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

slide27

Thank You!

Questions?