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Chapter 6: Modeling and Representation. Service-Oriented Computing: Semantics, Processes, Agents – Munindar P. Singh and Michael N. Huhns, Wiley, 2005. Highlights of this Chapter. Integration versus Interoperation Common Ontologies Knowledge Representations Relationships Hierarchies - PowerPoint PPT Presentation
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Chapter 6:Modeling and Representation
Service-Oriented Computing: Semantics, Processes, Agents– Munindar P. Singh and Michael N. Huhns, Wiley, 2005
Chapter 6 2Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Highlights of this Chapter
Integration versus Interoperation Common Ontologies Knowledge Representations Relationships Hierarchies Modeling Fundamentals Unified Modeling Language (UML)
Chapter 6 3Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Integration versus Interoperation
Application
Transform
Application Application Application Application
Integration EDI XML Portal + Workflow Solution
APIsolution
Standard DataFormat
XML-Based DataExchange Format
Application Application Application Application Application
Distributed application: XML +Web services + workflow
TransformationTransformation
Transform Transform Transform Transform
Transform Transform Transform Transform Transform
Tight coupling Loose coupling
Chapter 6 4Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Modeling and Composing Services
RequirementsAnalysis
ConceptualSchema
BackgroundKnowledge
Universe ofDiscourse
Universe ofDiscourse
RequirementsAnalysis
CO
MP
RE
HE
ND
ConceptualSchema
ServiceInterface
ServiceInterface
DesignService
Implementation
DesignService
Implementation
MA
P
INT
ER
OP
ER
AT
E
Chapter 6 5Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Dimensions of Abstraction: 1
Abstractions of information resources capture knowledge that is relevant for interoperation; think of these as constraints that must be discovered and represented
Data Domain specifications Value ranges, e.g., Price >= 0 Allow/disallow null values
Chapter 6 6Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Dimensions of Abstraction: 2
Structure Taxonomic representations and relationships
such as in schemas and views, e.g., securities are stocks
Specializations and generalizations of domain concepts, e.g., stocks are a kind of liquid asset
Value maps, e.g., S&P A+ rating corresponds to Moody’s A rating
Semantic data properties, sufficient to characterize the value maps, e.g., some stock price databases consider daily averages; others closing prices
Cardinality constraints Integrity constraints, e.g., each stock must
have a unique SEC identifier
Chapter 6 7Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Dimensions of Abstraction: 3
Process Procedures, i.e., how to process information,
e.g., how to decide what stock to recommend Preferences for accesses and updates in case
of data replication (based on recency or accuracy of data)
Preferences to capture view update semantics Contingency strategies, e.g., whether to
ignore, redo, or compensate Contingency procedures, i.e., how to
compensate transactions Flow, e.g., where to forward requests or results Temporal constraints, e.g., report tax data
every quarter
Chapter 6 8Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Dimensions of Abstraction: 4
Policy Security, i.e., who has rights to access or
update what information? (e.g., customers can access all of their accounts, except blind trusts)
Authentication, i.e., a sufficient test to establish identity (e.g., passwords, retinal scans, or smart cards)
Bookkeeping (e.g., logging all accesses)
Chapter 6 9Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Value Maps: 1
A value map relates the values expressed by different services
Key properties Totality Order preservation Consistent inversion
Chapter 6 10Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Value Maps: 2
A++
Aaa
A.M. Best Moody’s
A+
Aa1
A
Aa2
A-
Aa3
B++
A1
B+
A2
B
A3
B-
Baa1
C++
Baa2
C+
Baa3
C
Ba1
C-
Ba2
D
Ba3
E
B1
F
B2
B3
Caa
Ca
C
A++
Aaa
A.M. Best Moody’s
A+
Aa1
A
Aa2
A-
Aa3
B++
A1
B+
A2
B
A3
B-
Baa1
C++
Baa2
C+
Baa3
C
Ba1
C-
Ba2
D
Ba3
E
B1
F
B2
B3
Caa
Ca
C
(a) A consistent value map (b) A value map that violates consistent inversion
Chapter 6 11Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Ontology A specification of a conceptualization or a set of
knowledge terms for a particular domain, including
The vocabulary: concepts and relationships The semantic interconnections: relationships among
concepts and relationships Some simple rules of inference and logic
Some representation languages for ontologies: Uniform Modeling Language (UML) Resource Description Framework Language
Schema (RDFS) Web Ontology Language (OWL)
Some ontology editors: Protégé, Webonto, OilEd
Chapter 6 12Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Common Ontologies
A shared representation is essential to successful communication and interoperation For humans: physical, biological, and social world For computational agents: common ontology
(terms used in communication) Representative efforts are
Cyc (and Opencyc) WordNet (Princeton); LDOCE; OED Several upper-level ontologies, including by IEEE
Mostly stable concepts such as space, time, person, which can be used within various domains
Chapter 6 13Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Ontologies and Articulation Axioms
SeatingArrangement
Airplane
TransportationDevice
nonNegativeInteger
seats
nonNegativeInteger
range
numpassengers
Airliner
Flight
Airport
to from
equipment
CommercialTransportation
Device
PublicTransportation
Device
Itinerary
LocationClass ofService
classto Leg
from
uses
1*
Boeing777
JumboJet
CommonOntology
Travel Agent Service
User’s Agent
Mapping byhand, butwith toolsupport
Developing acommon ontology:• All at once• Incrementally viaconsensus
Chapter 6 14Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Knowledge Representation Expressive power Procedural (how) versus declarative
(what) Declarative pros: enables standardization,
optimization, improved productivity Declarative cons: nontrivial to achieve and
causes short-term loss of performance Trade-offs shifted by Web to favor
declarative modeling
Chapter 6 15Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Frames versus Descriptions
Frame-based approaches are intuitive but rely on names of classes and properties to indicate meaning
Description logics provide a computationally rigorous means to represent meaning; difficult for people
Managing this trade-off is a major challenge for Knowledge Representation
Chapter 6 16Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Exercise: Which Conceptualization is Most Expressive and Flexible?
awg22SolidBlueWire(ID5) blueWire(ID5, AWG22, Solid) solidWire(ID5, AWG22, Blue) wire(ID5, AWG22, Solid, Blue) wire(ID5)^size(ID5,
AWG22)^type(ID5, solid)^color(ID5, Blue)
Chapter 6 17Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Mappings among Ontologies Term-to-term (one-to-one), e.g.,
hookupWireO1 ´ wireO2
Many-to-one, e.g.,solidWireO1(x, size, color) Æ strandedWireO1(x, size, color)
´ wireO2(x, size, color, (Stranded|Solid))
Many-to-many, e.g.,solidBlueWireO1(x, size) Æ
solidRedWireO1(x, size) Æ
strandedBlueWireO1(x, size) Æ
strandedRedWireO1(x, size)
´solidWireO2(x, size, (Red|Blue)) Æ
strandedWireO2(x, size, (Red|Blue))
Chapter 6 18Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Unified Modeling Language (UML) for Ontologies
PurchaseOrder ShippingDetail
BillingDetailItemDetail
Seller Buyer Account
Organization Person
1 *
1*
1*
1* 1 *1 *
Class diagrams without members
Chapter 6 19Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Comparison of Modeling Languages
Chapter 6 20Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and
Michael Huhns
Chapter 6 Summary
Shared models are essential for interoperation Based on shared ontologies or
conceptualizations Good models must accommodate several
important considerations Modeling requires several subtle considerations
Declarative representations facilitate reasoning about and managing models
Formalization enables ensuring correctness of models and using them for interoperation
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