Semantic Geospatial Data
Exchange & Access Control
Latifur Khan
Ashraful Alam
Ganesh Subbiah
Bhavani Thuraisingham
Outline
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Traditional Web Services
Semantic Web Services
Semantic Web Services for Geospatial
Data
Semantic Access Control
Geospatial Data Integration
GRDF for Distributed Geospatial Data
Semantic Web Services Vision
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Static
WWW
URI, HTML, HTTP
500 million users
more than 3 billion pages
Semantic Web Services Vision
Serious Problems in
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Static
information finding,
information extracting,
information representing,
information interpreting
and
and information
maintaining.
WWW
Semantic Web
URI, HTML, HTTP
RDF, RDF(S), OWL
Semantic Web Services Vision
Dynamic
Static
Web Services
UDDI, WSDL, SOAP
Bringing the computer back as
a device for computation
WWW
Semantic Web
URI, HTML, HTTP
RDF, RDF(S), OWL
Semantic Web Services Vision
Bringing the web to its full potential
Dynamic
Static
UDDI, WSDL, SOAP
Semantic Web
Services
WWW
Semantic Web
URI, HTML, HTTP
RDF, RDF(S), OWL
Web Services
DAGIS Vision
Bringing the web to its full potential for
Geospatial Domain
Dynamic
Geo-Web
Services
UDDI, WSDL,
SOAP,OGC -WS
Static
WWW
URI, HTML, HTTP
Geospatial
Semantic Web
Services DAGIS
Geospatial
Semantic Web
GRDF
Geospatial Interoperability
Challenges
Syntactic Naming Heterogeneity
Distance – Float or Distance Type
Structural Naming Heterogeneity
Location expressed by two separate coordinates or by a point data
type
Semantic Heterogeneity
Distance computed on the sphere or in a plane
Service Discovery and Evaluation
Hydrologist in charge of Flood Warnings has 3 Water-level Service
Providers.
Service Composition
Service to Compute the outline of a Toxic cloud after a Chemical Spill.
Motivating Scenario
Query: “Find movie theaters
within 30 miles of 75080”
within, near, overlap – Geospatial
Operators
Theaters, Restaurants – Businesses
(Non-Geospatial data)
Miles – Distance Unit
75080 , Richardson – Geo References
Cinemark
Movies 10
Radisson Hotel Dallas NorthRichardson
What is a Web Service ?
The human-centric Web
The Application-centric Web
The automated Web
OWL-S Upper Ontology
•Capability specification
•General features of the Service
• Quality of Service
• Classification in Service
taxonomies
• Mapping to WSDL
• communication protocol (RPC, HTTP, …)
• marshalling/serialization
• transformation to and from XSD to OWL
• Control flow of the service
•Black/Grey/Glass Box view
• Protocol Specification
• Abstract Messages
Query Grammar
Define, Geospatial Objects as GB, Geospatial Operator as
GO, Polygon Type as PT and Extension as E. Then,
 <Query> :: <GB> [<GO>] [<PT>] [<E>]
<GB>
 <GB> :: Non-geometric Concept
 <GO> :: <Operator Terminal>
 <PT> :: <Polygon Terminal>
 <E> :: Distance
 <Operator Terminal> :: Within | Touches On |
 Intersect | Between
 <Polygon Terminal> :: Straight line | Circle
Generation of Semantic enabled
profile for Geospatial Query
Theaters
Query Profile
ZipCode
Miles
Generated OWL-S Semantic Profile
http://www.utdallas.edu/~gxs059000/Query.owl
Domain Ontology (Snapshot)
http://www.utdallas.edu/~gxs059000/OGCServiceontology.owl
Geospatial Service Selection
and Discovery
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DAGIS Agent
OWL-S MX Matchmaker
Best Service Match : Functionality,QoS
Degrees of Match:
EXACT < PLUG-IN < SUBSUMES< SUBSUMED-BY<LOGIC
BASED FAIL < NEAREST-NEIGHBOUR < FAIL
Geospatial Service Invocation
Theaters
-OWL-S grounding
-WSDL Grounding
-Service Invocation
through AXIS
GetTheater
Process
ZipCode
Miles
GetTheater Atomic Process
DAGIS System Architecture
Service
Provider - 1
…
…
1. Register/
Advertise DAGIS Matchmaker
Service
Provider - n
3. Service Discovery,
Service Enactment
DAGIS
Interface
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DAGIS Query Interface
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OWL-S MatchMaker
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OWL-DL Reasoner for
Matchmaker
Service Providers
Reasoner/
Matching Engine
DAGIS
Agent
2. Query
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DAGIS for Complex Queries
Find Movie Theaters within 30 Miles from Richardson, TX
Client
DAGIS
Agent
1. Query
Profile
MatchMaker
2. Service Discovery
5.Return Dynamic
Service URI
DAGIS
Composer
3.
Compose
Selection
Composer
Sequencer
4. Construct
Sequence
Richardson
Zipcode
Finder
TX
30 Miles
Theater
Finder
Theaters
DAGIS Composer Algorithm
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Recursive Back Chaining Inference Mechanism
(Regression Planning)
Richardson
TX
30 Miles
Zipcodefinde
r
GetTheater
Movie Theaters
Inputs:= City, State , Distance Output := Movie Theaters NO Service Provider
Inputs:= City, State
Output := ZipCode
Inputs:= ZipCode , Distance Output := MovieTheaters
ZipCodeFinder
Theater Finder
DAGIS Query Interface
DAGIS Integration Scenarios
Query
Availability
Service Type
Service Invoked
Find Movie Theaters
within 30 Miles of 75080
YES
Atomic (Single) Service
Provider
GetTheatersAndMoviesS
ervice
Find Movie Theaters
within 30 Miles of
Richardson,TX
NO
DAGIS Composes two
Atomic Services:
ZipCodeFinder ,
GetTheatersAndMovies
Find Movie Theaters
within 30 Miles of 75080
QoS: Response Time 30
Sec
YES
Two services with QoS
40 Sec and 50 Sec
Available
Find Movie Theaters
within 30 Miles of 75080
NO
Atomic Service
Atomic Service
GetTheatersAndMoviesS
ervice
QoS Response Time 40
Sec
GetTheatersService
Online Ontology Repository
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http://www.utdallas.edu/~gxs059000/QoSUpper.owl
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http://www.utdallas.edu/~gxs059000/QoSMiddle.owl
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http://www.utdallas.edu/~gxs059000/GetTheatersAndMovies.owl
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http://www.utdallas.edu/~gxs059000/GetTheatersAndMovies1.owl
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http://www.utdallas.edu/~gxs059000/GetTheaters.owl
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http://www.utdallas.edu/~gxs059000/ZipCodeFinder.owl
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http://www.utdallas.edu/~gxs059000/DAGISCompServ1.owl
Geospatial Operators
Between, Near, Within etc.
 Precision required for geospatial tasks
 How to define the operator semantics?
(‘Between’ A and B  ‘Between’ B and A)
 Context required for better precision
(e.g., near 20 miles)
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Geospatial Operator (Google
Maps)
Geospatial Operator (Google
Maps)
Geospatial Operator (DAGIS)
Geospatial Data Integration
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Intra-domain Integration Problem
• All participating domains are of geographic
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nature.
Controlled environment, controlled data.
Inter-domain Integration Problem
• Integration of geospatial and non-geospatial
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data
Controlled data, but chaotic environment
Inter-domain Integration Issues
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Disparate Sources:
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Disparate Types:
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• Sensors, Web pages, Satellites, Excel sheets
• Vector data, Tabular, Temporal data
Disparate Formats:
• GML, Shapefile, Gedcom, HTML
Geospatial Data Integration
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Emerging trends in geospatial
applications
• Google Earth, Emergency Response System,
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Location-based Services
Requires free mixing of geospatial with nongeospatial data
Hard to do with XML-based approaches
Semantic Web (RDF Model)
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Logic-aware languages
Ontology sharing and reuse
RDF Data Model:
Subject
Object
Predicate
GRDF
GRDF (Geospatial Resource Description Framework)
• Adds semantics to data
• Loosely-structured (easy to freely mix with other
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non-geospatial data)
Semantically extensible
ComputerScience
Building
hasExtent
(33.98111, -96.4011)
(33.989999, -96.4022)
GRDF Example (Topology)
<owl:Class rdf:ID=“Edge"></owl:Class>
<owl:Class rdf:ID=“Node"></owl:Class>
<owl:Class rdf:ID=“Face">
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<rdfs:subClassOf>
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<owl:Restriction>
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<owl:minCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#int"
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>1</owl:minCardinality>
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<owl:onProperty>
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<owl:DataTypeProperty rdf:ID=“hasEdge"/>
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</owl:onProperty>
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</owl:Restriction>
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…
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</owl:Class>
Seamless Data Manipulation
DAGIS
Subject
Predicate
Object
Provider A
Provider B
Datastore
Geospatial Data Integration
(cont.)
Upper-level ontologies
Abstract Definitions of Main Geospatial Concepts
Mid-level ontology (GRDF)
Concrete Definitions of All Relevant Geospatial Concepts
Domain ontologies
Hydrology
ontology
Cartography
ontology
Image
ontology
Semantic Access Control (SAC)
Traditional Access
Control
Semantic Web
Semantic Access Control
Motivation
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Shortcomings of Traditional Access Control
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Proprietary systems
Lack of modularity
Changes in access control schemas break the system
Changes in data schemas break the system
Path to resources (e.g., XPATH) is clumsy
//school/department/professor/personal/ssn – LONG!
Non-optimal for distributed/federation environment
Modularity Problem
People this policy applies to
Resources this policy applies to
Target
Box
Actions allowed for this policy
SAC Ontology
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Written in OWL (Web Ontology Language)
User-centric
Modular
Easily extensible
Available at :
http://utd61105.campus.ad.utdallas.edu/geo/voc/newaccessonto
Geo-WS Security
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Data providers (e.g., geospatial clearinghouses, research
centers) need access control on serviceable resources.
Access policies have geospatial dimension
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Bob has access on Building A
Bob does NOT have access on Building B
Building A and B have overlapping area
Current access control mechanisms are static and nonmodular.
Geo-WS Security: Policy
Components
Policy Set
Subjects
Resources
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Subjects:
Resources:
Actions:
Conditions:
Actions
Condition
Software Agents or Human clients
Assets exposed through WS
Read, Write, Execute
Additional constraints (e.g., geospatial
parameters) on policy enforcement
Geo-WS Security: Architecture
Geospatial Semantic WS Provider
Client
D
A
G
I
S
Enforcement Module
Decision
Module
Authorization
Module
Semantic-enabled Policy DB
Web Service Client Side
Web Service Provider Side
Geo-WS Security: Semantics
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Policy rules are based on description logic (DL).
DL allows machine-processed deductions on policy base.
Example 1:
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DL Rule: ‘Stores’ Inv. Prop. ‘Is Stored In’
Fact:
Airplane_Hanger(X) ‘stores’ Airplane(Y)
Example 2:
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DL Rule: ‘Is Located In’ is Symmetric
Fact:
Polygon(S) ‘Is Located In’ Polygon(V)
Polygon(V) ‘Is Located In’ Polygon(T)
Geo-WS Security: Inferencing
Semantic-enabled Policy DB
Obvious
facts
Deduced
facts
Inferencing Module
Geospatial
Data
Store
SAC in Action
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Environment: University Campus
Campus Ontology
http://utd61105.campus.ad.utdallas.edu/geo/voc/campusonto
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Main Resources
• Computer Science Building
• Pharmacy Building
• Electric Generator in each Building
SAC in Action
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User Access:
• Bob has ‘execute’ access to all Building
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Resources
Bob doesn’t have any access to CS Building
Bob has ‘modify’ access to Building resources
within a certain geographic extent
Policy File located at
http://utd61105.campus.ad.utdallas.edu/geo/voc/policyfile1
Future Directions
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QoS based Selection for Complex
Queries
Automatic Trust Negotiation for DAGIS
Define a specification for access control
semantics
Geospatial dataset development
Thank You!