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Applying Semantics to Service Oriented Architectures
Oasis Symposium 2006
The Meaning of Interoperability 9-12 May, San Francisco
Presenters:Adrian Mocan Mick KerriganMichal Zaremba
Special Thanks to:Emilia CimpianThomas HaselwanterBrahmananda Sapkota
OASIS Symposium 2006 2
The Aims of this Tutorial
• Introduce the aims & challenges of Semantic Web Services (SWS) - the WSMO approach
• Describe how SOA can be used with Semantic Web Services – WSMX Approach
• Semantic SOA enables interoperability
OASIS Symposium 2006 3
Overview
• Introduction to SWS– WSMO
• Introduction to SOA– WSMX
• Means of Interoperability• Web Service Modeling Toolkit (WSMT)• Conclusions
OASIS Symposium 2006 4
Overview
• Introduction to SWS– WSMO
• Introduction to SOA– WSMX
• Means of Interoperability• WSMT• Conclusions
OASIS Symposium 2006 5
Introduction to Semantic Web Services
• Introduction to Semantic Web
• Introduction to Web services
Semantic Web Services
OASIS Symposium 2006 6
500 million user
more than 3 billion pages
Static WWWURI, HTML, HTTP
Semantic Web and Web Services – The Vision
OASIS Symposium 2006 7
Static WWWURI, HTML, HTTP
Serious Problems inSerious Problems ininformation finding,information finding,information extracting,information extracting,Information representing,Information representing,information interpreting and information interpreting and information maintaining.information maintaining.
Semantic WebRDF, RDF(S), OWL
Semantic Web and Web Services
OASIS Symposium 2006 8
Static WWWURI, HTML, HTTP
Bringing the Bringing the computer back computer back as a device for as a device for computationcomputation
Semantic WebRDF, RDF(S), OWL
Dynamic Web ServicesUDDI, WSDL, SOAP
Semantic Web and Web Services – The Vision
OASIS Symposium 2006 9
Static WWWURI, HTML, HTTP
Bringing Bringing the Web the Web to its full to its full potentialpotential
Semantic WebRDF, RDF(S), OWL
Dynamic Web ServicesUDDI, WSDL, SOAP
Intelligent WebServices
Semantic Web and Web Services – The Vision
OASIS Symposium 2006 10
Formal, explicit specification of a shared conceptualization
commonly accepted understanding
conceptual model of a domain
(ontological theory)
unambiguous terminology definitions
machine-readability with computational
semantics
Ontology Definition
OASIS Symposium 2006 11
Ontology Example
Concept conceptual entity of the domain
Attribute property of a concept
Relation relationship between concepts or properties
Axiom coherent description between Concepts / Properties / Relations via logical expressions
Person
Student Professor
Lecture
isA – hierarchy (taxonomy)
name email
studentnr.
researchfield
topiclecture
nr.
attends holds
holds(Professor, Lecture) Lecture.topic Professor.researchField
OASIS Symposium 2006 12
Ontology Languages
• Requirements: – ”expressivity“
• knowledge representation
• ontology theory support
– ”reasoning support“ • sound (unambiguous, decidable)
• support of reasoners / inference engines
• Semantic Web languages: – web compatibility – Existing W3C Recommendations:
• XML, RDF, OWL
OASIS Symposium 2006 13
Semantic Web Language Layer Cake
OASIS Symposium 2006 14
Web Services
• Web Services [Stencil Group]• loosely coupled, reusable components• encapsulate discrete functionality • distributed • programmatically accessible over standard internet
protocols• add new level of functionality on top of the current web
OASIS Symposium 2006 15
Using Web Services
OASIS Symposium 2006 16
Using Web Services
OASIS Symposium 2006 17
Lack of SWS standards
• Current technology does not allow realization of any of the parts of the Web Service usage process:– Only syntactical standards available– Lack of fully developed semantic markup languages– Lack of semantically marked up content and services– Lack of semantically enhanced repositories– Lack of frameworks that facilitate discovery, composition and
execution– Lack of tools and platforms that allow to semantically enrich
current Web content
OASIS Symposium 2006 18
Semantic Web Services
• Define exhaustive description frameworks for describing Web Services and related aspects (Web Service Description Ontologies)
• Support ontologies as underlying data model to allow machine supported data interpretation (Semantic Web aspect)
• Define semantically driven technologies for automation of the Web Service usage process (Web Service aspect)
OASIS Symposium 2006 19
Semantic Web Services (2)
Usage Process:
• Publication: Make available the description of the capabilities of a service
• Discovery: Locate different services suitable for a given task • Selection: Choose the most appropriate services among the
available ones • Composition: Combine services to achieve a goal• Mediation: Solve mismatches (in data or process) among the
combined services• Execution: Invoke services following programmatic conventions
OASIS Symposium 2006 20
Semantic Web Services (3)
Usage Process – execution support
• Monitoring: Control the execution process• Compensation: Provide transactional support and undo or mitigate
unwanted effects• Replacement: Facilitate the substitution of services by equivalent
ones• Auditing: Verify that service execution occurred in the expected way
OASIS Symposium 2006 21
Semantic Web Services =
Semantic Web Technology +
Web Service Technology
Summary
OASIS Symposium 2006 22
Overview
• Introduction to SWS– WSMO
• Introduction to SOA– WSMX
• Means of Interoperability• WSMT• Conclusions
OASIS Symposium 2006 23
Web Service Modeling Ontology (WSMO)
• A conceptual model for Semantic Web Services: – Ontology of core elements for Semantic Web Services
– a formal description language (WSML)
– execution environment (WSMX)
• … derived from and based on the Web Service Modeling Framework WSMF
• an European Semantic System Initiative – “ESSI Cluster” Working Group
– joint European research and development initiative
OASIS Symposium 2006 24
A Conceptual Model for SWS
A Formal Language for WSMO
A Rule-based Language for SWS
Execution Environment for WSMO
WSMO Working Groups
OASIS Symposium 2006 25
WSMO Design Principles
Web Compliance Ontology-Based
Strict DecouplingOf Modeling Elements
Centrality of Mediation
Ontological Role Separation
Description versus Implementation
Execution Semantics
WSMO
OASIS Symposium 2006 26
Objectives that a client wants toachieve by using Web Services
Provide the formally specified terminologyof the information used by all other components
Semantic description of Web Services: - Capability (functional)- Interfaces (usage)
Connectors between components with mediation facilities for handling heterogeneities
WSMO Top Level Notions
OASIS Symposium 2006 27
Non-Functional Properties
Every WSMO elements is described by properties that contain relevant, non-functional aspects
• Dublin Core Metadata Set: – complete item description
– used for resource management
• Versioning Information – evolution support
• Quality of Service Information – availability, stability
• Other – Owner, financial
OASIS Symposium 2006 28
Dublin Core Metadata Contributor Coverage Creator Description Format Identifier Language Publisher Relation Rights Source Subject Title
Type
Quality of Service Accuracy NetworkRelatedQoSPerformanceReliability RobustnessScalability Security Transactional
Trust
Other Financial Owner TypeOfMatch Version
Non-Functional Properties List
OASIS Symposium 2006 29
WSMO Ontologies
Provide the formally specified terminology
of the information used by all other components
Semantic description of Web Services: - Capability (functional)- Interfaces (usage)
Connectors between components with mediation facilities for handling heterogeneities
Objectives that a client wants to achieve by using Web Services
OASIS Symposium 2006 30
Ontology Usage & Principles
• Ontologies are used as the ‘data model’ throughout WSMO – all WSMO element descriptions rely on ontologies – all data interchanged in Web Service usage are ontologies – Semantic information processing & ontology reasoning
• WSMO Ontology Language WSML– conceptual syntax for describing WSMO elements – logical language for axiomatic expressions (WSML Layering)
• WSMO Ontology Design – Modularization: import / re-using ontologies, modular approach
for ontology design
– De-Coupling: heterogeneity handled by OO Mediators
OASIS Symposium 2006 31
Ontology Specification
• Non functional properties (see before)
• Imported Ontologies importing existing ontologies where no heterogeneities arise
• Used mediators OO Mediators (ontology import with terminology mismatch handling)
• Ontology Elements:Concepts set of concepts that belong to the ontology, incl.
Attributes set of attributes that belong to a concept
Relations define interrelations between several concepts
Functions special type of relation (unary range = return value)
Instances set of instances that belong to the represented ontology
Axioms axiomatic expressions in ontology (logical statement)
OASIS Symposium 2006 32
WSMO Web services
Provide the formally specified terminology
of the information used by all other components
Semantic description of Web Services: - Capability (functional)- Interfaces (usage)
Connectors between components with mediation facilities for handling heterogeneities
Objectives that a client wants to achieve by using Web Services
OASIS Symposium 2006 33
Web serviceImplementation(not of interest in Web Service Description)
Choreography --- Service Interfaces ---
Capability
functional description
WS
WS
- Advertising of Web Service- Support for WS Discovery
client-service interaction interface for consuming WS - External Visible Behavior- Communication Structure - ‘Grounding’
realization of functionality by aggregating other Web Services - functional decomposition - WS composition
Non-functional Properties
DC + QoS + Version + financial
- complete item description- quality aspects - Web Service Management
WS
Orchestration
WSMO Web service description
OASIS Symposium 2006 34
Capability Specification
• Non functional properties • Imported Ontologies • Used mediators
– OO Mediator: importing ontologies with mismatch resolution – WG Mediator: link to a Goal wherefore service is not usable a priori
• Pre-conditions – What a web service expects in order to be able to provide its service– Define conditions over the input.
• Assumptions – Conditions on the state of the world that has to hold before the Web Service can
be executed
• Post-conditions – Describes the result of the WS in relation to the input, and conditions on it
• Effects – Conditions on the state of the world that hold after execution of the – Web Service (i.e. changes in the state of the world)
OASIS Symposium 2006 35
VTAService
Date
Time
Flight, Hotel
Error
Confirmation
Hotel Service
Flight Service
Date, Time
Hotel
Error
Date, Time
Flight
Error
When the service is requested
When the service requests
Choreography & Orchestration
VTA example:
• Choreography = how to interact with the service to consume its functionality • Orchestration = how service functionality is achieved by aggregating other Web services
Confirmation
Confirmation
OASIS Symposium 2006 36
Choreography Aspects
• Interface for consuming Web Service
– External Visible Behavior• those aspects of the workflow of a Web Service where Interaction is required • described by workflow constructs: sequence, split, loop, parallel
– Communication Structure • messages sent and received • their order (communicative behavior for service consumption) • choreography related errors (e.g. input wrong, message timeout, etc.)
– Grounding • concrete communication technology for interaction
– Formal Model • reasoning on Web Service interfaces (service interoperability)• allow mediation support on Web Service interfaces
OASIS Symposium 2006 37
- decomposition of service functionality
- all service interaction via choreographies
Control Structure for aggregation of other Web Services
WS
Web S
ervice Business Logic
1
2
3
4
WS
State in Orchestration
Control Flow
Data Flow
Service Interaction
Orchestration Aspects
OASIS Symposium 2006 38
Orchestration Aspects
• Service interfaces are concerned with service consumption and interaction
• Choreography and Orchestration as sub-concepts of Service Interface
• Common requirements for service interface description: – represent the dynamics of information interchange during service
consumption and interaction – support ontologies as the underlying data model – appropriate communication technology for information interchange– sound formal model / semantics of service interface specifications in
order to allow operations on them.
OASIS Symposium 2006 39
Ontologies as data model: - every resource description based on ontologies - every data element interchanged is ontology instance
Formal description of service interfaces: - ASM-based approach - allows reasoning & mediation
workflow constructs as basis for describing service interfaces: - workflow based process models for describing behavior - on basis of generic workflow constructs (e.g. van der Aalst)
Choreography: - interaction of services / service and client - a „choreography interface“ describes the behavior of a Web Service for client-service interaction for consuming the service
Orchestration: - how the functionality of a Web Service is achieved by aggregating other Web Services - extends Choreography descriptions by control & data flow constructs between orchestrating WS and orchestrated WSs.
Grounding: - making service interfaces executable - currently grounding to WSDL
Conceptual models
User language - based on UML2 activity diagrams - graphical Tool for Editing & Browsing Service Interface Description
Choreography and Orchestration - Overview
OASIS Symposium 2006 40
WSMO Goals
Provide the formally specified terminologyof the information used by all other components
Semantic description of Web Services: - Capability (functional)- Interfaces (usage)
Connectors between components with mediation facilities for handling heterogeneities
Objectives that a client wants to achieve by using Web Services
OASIS Symposium 2006 41
Goals
• Ontological De-coupling of Requester and Provider
• Goal-driven Approach– derived from AI rational agent approach
– Requester formulates objective independently
– ‘Intelligent’ mechanisms detect suitable services for solving the Goal
– allows re-use of Services for different purposes
• Usage of Goals within Semantic Web Services– A Requester, that is an agent (human or machine), defines a Goal to be
resolved
– Web Service Discovery detects suitable Web Services for solving the Goal automatically
– Goal Resolution Management is realized in implementations
OASIS Symposium 2006 42
Goal Specification
• Non functional properties
• Imported Ontologies
• Used mediators
– OO Mediators: importing ontologies with heterogeneity resolution
– GG Mediator:
• Goal definition by reusing an already existing goal• allows definition of Goal Ontologies
• Requested Capability
– describes service functionality expected to resolve the objective
– defined as capability description from the requester perspective
• Requested Interface
– describes communication behaviour supported by the requester for consuming a Web Service (Choreography)
– Restrictions / preferences on orchestrations of acceptable Web Services
OASIS Symposium 2006 43
WSMO Mediators
Provide the formally specified terminology
of the information used by all other components
Semantic description of Web Services: - Capability (functional)- Interfaces (usage)
Connectors between components with mediation facilities for handling heterogeneities
Objectives that a client wants to achieve by using Web Services
OASIS Symposium 2006 44
Mediation
• Heterogeneity … – Mismatches on structural / semantic / conceptual / functional / level – Occur between different components that shall interoperate– Especially in distributed & open environments like the Internet
• Concept of Mediation (Wiederhold, 94): – Mediators as components that resolve mismatches– Declarative Approach:
• Semantic description of resources • ‘Intelligent’ mechanisms that resolve mismatches independent of content
– Mediation cannot be fully automated (integration decision)
• Levels of Mediation within Semantic Web Services (WSMF): (1) Data Level: mediate heterogeneous Data Sources (2) Functional Level: mediate mismatches between Web Service/Goal and Web Service/Goals
functionalities(3) Process/Protocol Level: mediate heterogeneous Business Processes/Communication
Patterns
• Layers of Mediators– Specification Layer – WSMO Mediators– Implementation Layer – Levels of Mediation
OASIS Symposium 2006 45
WSMO Mediators Overview
OASIS Symposium 2006 46
WSMO Mediator
uses a Mediation Service via
Source Component
Source Component
TargetComponent 1 .. n
1
Mediation Services
- as a Goal - directly- optionally incl. Mediation
Mediator Structure
Specification layer
Implementation layer
OASIS Symposium 2006 47
OO MediatorMediation Service
Train ConnectionOntology (s1)
Purchase Ontology (s2)
Train Ticket Purchase Ontology
Mediation Services
Discovery
Merging 2 ontologies
OO Mediator - Example
Goal:“merge s1, s2 and
s1.ticket subclassof s2.product”
OASIS Symposium 2006 48
GG MediatorMediation Service
Source Goal“Buy a ticket”
Target Goal “Buy a Train Ticket”
postcondition: “aTicket memberof trainticket”
GG Mediators
• Aim:– Support specification of Goals by re-using existing Goals – Allow definition of Goal Ontologies (collection of pre-defined Goals)– Terminology mismatches handled by OO Mediators
• Example: Goal Refinement
OASIS Symposium 2006 49
• WG Mediators:– link a Web Service to a Goal and resolve occurring mismatches
– match Web Service and Goals that do not match a priori
– handle terminology mismatches between Web Services and Goals broader range of Goals solvable by a Web Service
• WW Mediators:– enable interoperability of heterogeneous Web Services support automated collaboration between Web Services
– OO Mediators for terminology import with data level mediation
– Protocol Mediation for establishing valid multi-party collaborations
– Process Mediation for making Business Processes interoperable
WG & WW Mediators
OASIS Symposium 2006 50
Data Level Mediation
• Scope– Solving terminological mismatches
• Related Aspects / Techniques: – Ontology Integration (Mapping, Merging, Alignment) – Data Lifting & Lowering– Transformation between Languages / Formalisms
• Terminology Mismatches Classification – Conceptualization Mismatches
• same domain concepts, but different conceptualization• different levels of abstraction • different ontological structure • => resolution only includs human intervention
– Explication Mismatches • mismatches between:
– T (Term used), D (definition of concepts), C (real world concept)• => automated resolution partially possible
OASIS Symposium 2006 51
Functional Level Mediation
• Scope– Solving functional mismatches between goals and/or ws
• Related Aspects/Techniques– Discovery– Semantic Matchmaking
• Matchmaking Mismatches
= G/WS = G/WS
X
Exact Match Subsumption Match Intersection Match No MatchPlugIn Match
OASIS Symposium 2006 52
Process Level Mediation
• Scope– Resolves communication mismatches and establish behavior
compatibility
• Related Aspects/Techniques– Data and control flow composition
• Process Mismatches– Signature terminology mismatches (need for data level mediation)
– Communication/behavior mismatches
Business Partner1Business Partner1
Business Partner2Business A
B B
Business Partner1Business Partner1
Business Partner2Business Partner2
A B
B A
Business Partner1Business Partner1
Business Partner2Business Partner2
A and BA
B
Business Partner1Business Partner1
Business Partner2Business Partner2
A
BA and B
PM
PM
PM
PM
Business Partner1Business Partner1
Business Partner2Business Partner2
A
AckA
APM
OASIS Symposium 2006 53
WSMO Mediators and Mediation Levels
• ooMediator– Data Level Mediation
• ggMediator– Data Level Mediation– Functional Level Mediation
Ex:
• wgMediator– Data Level Mediation– Functional Level Mediation– Process Level Mediation
• wwMediator– Data Level Mediation– Functional Level Mediation– Process Level Mediation
internal business logic of
Web Service(not of interest in Service
Interface Description)
internal business logic of
Web Service(not of interest in Service
Interface Description)
WW
Med
iator
OASIS Symposium 2006 54
Overview
• Introduction to SWS– WSMO
• Introduction to SOA– WSMX
• Means of Interoperability• WSMT• Conclusions
OASIS Symposium 2006
Key Enablers
Information Technology versus Mission of Organizations
• People (e.g., organization structure, human capital)
• Business Processes• IT (e.g., systems)• Physical Infrastructure (e.g.,
facilities, workplace environment)
• Goals
• Objectives
• Strategy selection
• Value Proposition development
• Long term vision alignment
• Critical success factors for customers and service offerings
• Specific definition functional performance
Mission
Strategies
Capabilities
OASIS Symposium 2006 56
Existing Architectures do not scaleExisting Architectures do not scale
Existing IT architectures cannot support changing needs
AgilityAgility
IT assets cannot be easily repositioned in response to changing requirements
No solution for efficient intra- and inter-organization information sharing
Decision cycles are unnecessarily lengthened by data stovepipes
IT assets cannot be easily repositioned in response to changing requirements
No solution for efficient intra- and inter-organization information sharing
Decision cycles are unnecessarily lengthened by data stovepipes
Process HeterogeneityProcess Heterogeneity
Systems, organizations units and network of partners duplicate the same work
Information stovepipes require point-to-point integrations that limit flexibility and create maintenance overhead
More efforts spent connecting systems together than adding mission critical capabilities
Systems, organizations units and network of partners duplicate the same work
Information stovepipes require point-to-point integrations that limit flexibility and create maintenance overhead
More efforts spent connecting systems together than adding mission critical capabilities
Data HeterogeneityData Heterogeneity
Difficult to determine “what data means” fosters duplicate applications and data
Inability of applications to interoperate due to platform incompatibility Data used across an organization is often inconsistent and potentially inaccurate
Difficult to determine “what data means” fosters duplicate applications and data
Inability of applications to interoperate due to platform incompatibility Data used across an organization is often inconsistent and potentially inaccurate
CostsCosts
Duplicate data entry and manual data reunion require extra man power
Point-to-point integration shifts IT professionals towards repetitive employees to time consuming tasks
Integrating data stovepipes is expensive and wasteful
Operations and maintenance costs are a rising percentage of the budget
Duplicate data entry and manual data reunion require extra man power
Point-to-point integration shifts IT professionals towards repetitive employees to time consuming tasks
Integrating data stovepipes is expensive and wasteful
Operations and maintenance costs are a rising percentage of the budget
No agility, processes redundant, lack of system interactions, and everything is very costlyNo agility, processes redundant, lack of system interactions, and everything is very costly
OASIS Symposium 2006 57
SOA is an approach to organizing and using IT to match
and combine needs with capabilities in
support of the overall mission of an
enterprise
Capabilities performed by one for another to achieve a desired
outcome
Functionally aligning architecture to enable a collection of
independent services to be linked together to
solve a business problem
The fundamental organization of a system embodied in its capabilities,
their interactions, and the environment
Architecture
Oriented
Service
A Solution – Service Oriented Architectures
SOA - A paradigm that encourages organizations to re-think how their IT capabilities are organized
OASIS Symposium 2006 58
Traditional approach
to software architecture
Traditional approach
to software architecture
Analogy - traditional software architecture versus SOA
• No Agility to repair your car even for trivial tasks• A Process that is duplicative and inefficient• Costly to operate and maintain – keep many people
• Agility to repair cars quickly (next available mechanic takes care)• A Process that is efficient• Cost effective to operate and maintain
Service-Oriented Architecture
Service-Oriented Architecture
In garage every mechanic
specialize only in one type of car so it
does not matter what you want to repair you always have to wait for a
mechanic who knows your type of car; if he/she is sick
or on holiday you cannot repair your
car at all
You ask any mechanic in a
garage to repair your car –
model of your car does not
matter
“Separate Specialist” model “Service-Oriented” model
Mechanic does job himself or asks other
mechanics to take care of tasks he is not
capable to do
OASIS Symposium 2006 59
SOA Benefits
AgilityAgility
Focus more on core competencies
Creates a network of service requesters (consumers) and service providers (producers)
Enable enterprises to be more agile and respond quickly to changing requirements
Increase business flexibility through plug-and-play architecture and re-use of existing services
Focus more on core competencies
Creates a network of service requesters (consumers) and service providers (producers)
Enable enterprises to be more agile and respond quickly to changing requirements
Increase business flexibility through plug-and-play architecture and re-use of existing services
Process HeterogeneityProcess Heterogeneity
Allow interoperation with other systems without time consuming customization and point-to-point integration
Ensure system change is not a constraint on business or mission change
Facilitate integration with multiple solutions via open IT standards
Allow interoperation with other systems without time consuming customization and point-to-point integration
Ensure system change is not a constraint on business or mission change
Facilitate integration with multiple solutions via open IT standards
Data HeterogeneityData Heterogeneity
Improve semantics of data exchanged during business process execution
Maintain consistency of data across different systems
Remain platform, language, and vendor independent to remove IT barriers for using best-of-breed software packages
Improve semantics of data exchanged during business process execution
Maintain consistency of data across different systems
Remain platform, language, and vendor independent to remove IT barriers for using best-of-breed software packages
CostsCosts
Leverage existing IT infrastructure
Reduce costs of development of new functionalities by acquiring pre-built components/services
Lower maintenance costs
Leverage existing IT infrastructure
Reduce costs of development of new functionalities by acquiring pre-built components/services
Lower maintenance costs
SOA allows to align IT with mission of the organizationSOA allows to align IT with mission of the organization
Better agility, no redundancy, system interactions, and reduces overall costs of system maintenanceBetter agility, no redundancy, system interactions, and reduces overall costs of system maintenance
OASIS Symposium 2006 60
SOA Design Principles
• Strong Decoupling & Strong Mediation– autonomous components with mediators for interoperability
• Interface vs. Implementation– distinguish interface (= description) from implementation
(=program)
• Peer to Peer– interaction between equal partners (in terms of control)
OASIS Symposium 2006 61
Benefits of SOA
• Better reuse– Build new functionality (new execution semantics) on top of
existing Business Services
• Well defined interfaces – Manage changes without affecting the Core System
• Easier Maintainability– Changes/Versions are not all-or-nothing
• Better Flexibility
OASIS Symposium 2006 62
Semantically Empowered Service-oriented Architectures (SESA)
• Currently, computer science is in a new period of abstraction. • A generation ago we learnt to abstract from hardware and currently we
learn to abstract from software in terms of SERVICE oriented architectures (SOA).
• It is the service that counts for a customer and not the specific software or hardware that is used to implement the service.
• In a later stage, we may even talk in terms of problem-oriented architectures (or more positively expressed in terms of problem-solving oriented architectures) because SOAs are biased towards the service provider and not towards the customer that has a problem that needs to be solved.
OASIS Symposium 2006 63
Semantically Empowered Service-oriented Architecture (SESA)
• Service-oriented architectures will become quickly the leading software paradigm
• However, SOAs will not scale without significant mechanization of– Service discovery, service adaptation, negotiation, service
composition, service invocation, and service monitoring; and– Data and process mediation
• Therefore, machine processable semantics needs to be added to bring SOAs to their full potential
• Development of open standards (languages) and open source architectures and tools that add semantics to service descriptions
OASIS Symposium 2006 64
Semantic Web Services Infrastructure
• A service oriented architecture.• Reference implementation of WSMO
OASIS Symposium 2006 65
External SOA
SEE
Execution Management
(Execution Semantics)
Platform Service: Data Mediation
Platform Service:Discovery
Platform Service:[…]
User Service
User Service
User Service
User Service
User Service versus Platform Service in SWS Systems
OASIS Symposium 2006 66
Vertical and Horizontal Services
• Vertical services remain invisible to horizontal services, and during its execution, the horizontal services remain unaware that vertical services are executed together with them
• Vertical services invoke horizontal services, coordinating overall workflow, rather than horizontal service invoking the vertical
OASIS Symposium 2006 67
Overview
• Introduction to SWS– WSMO
• Introduction to SOA– WSMX
• Means of Interoperability• WSMT• Conclusions
OASIS Symposium 2006 68
WSMX Introduction
• Software framework for runtime binding of service requesters and service providers
• WSMX interprets service requester’s goal to– discover matching services– select (if desired) the service that best fits– provide mediation (if required)– make the service invocation
• Is based on the conceptual model provided by WSMO• Has a formal execution semantics• Service Oriented and event-based architecture
– based on microkernel design using technologies as J2EE, Hibernate, Spring, JMX, etc.
OASIS Symposium 2006 69
WSMX Motivation
• Provide middleware ‘glue’ for Semantic Web Services– Allow service providers focus on their business
• Provide a reference implementation for WSMO– Eat our own cake
• Provide an environment for goal based service discovery and invocation– Run-time binding of service requester and provider
• Provide a flexible Service Oriented Architecture– Add, update, remove components at run-time as needed
• Keep open-source to encourage participation– Developers are free to use in their own code
• Define formal execution semantics– Unambiguous model of system behaviour
OASIS Symposium 2006 70
WSMX Usage Scenario
OASIS Symposium 2006 71
WSMX Usage Scenario - P2P
• A P2P network of WSMX ‘nodes’• Each WSMX node described as a SWS• Communication via WSML over SOAP• Distributed discovery – first aim• Longer term aim - distributed execution environment
OASIS Symposium 2006 72
WSMX Usage Scenario - P2P
Peer
Internet
Message
Message
Internet
Message
MessagePeer
WSMX SWSARCHITECTURE
OASIS Symposium 2006 73
WSMX Usage Scenario - P2P
Exe
cutio
n M
an
ag
em
en
t
Ve
rtic
al S
erv
ice
s e
.g.
Se
curi
ty
Storage Reasoning
Communication (external)
Fault Handling Monitoring
Data MediationProcess
Mediation
Discovery Adaptation Composition Choreography
Application Services Layer
Problem Solving Layer
Base Services Layer
End User Tools Developer Tools
Internet
Message
MessagePeerPeer
Internet
Message
Message
OASIS Symposium 2006 74
Design Principles
• Strong Decoupling & Strong Mediation– autonomous components with mediators for interoperability
• Interface vs. Implementation– distinguish interface (= description) from implementation (=program)
• Peer to Peer– interaction between equal partners (in terms of control)
WSMO Design Principles == WSMX Design Principles
== SOA Design Principles
OASIS Symposium 2006 75
Benefits of SOA
• Better reuse– Build new functionality (new execution semantics) on top of
existing Business Services
• Well defined interfaces – Manage changes without affecting the Core System
• Easier Maintainability– Changes/Versions are not all-or-nothing
• Better Flexibility
OASIS Symposium 2006 76
WSMX Architecture
MessagingMessaging
Application Management
Application Management
Service Oriented
Architectures
Service Oriented
Architectures
WSMX
System Interface
WSMX ManagerWSMX Manager Core
Administration Framework Interface
Data and C
omm
unication Protocols Adapters
Adapter 1Adapter 2
Adapter n... Grounding
CM Wrapper
CommunicationManager
Interface
Invoker Receiver
RMWrapper
Resource Manager
Interface
ParserWrapper
Parser
Interface
DiscoveryWrapper
Discovery
Interface
SelectorWrapper
Selector
Interface
DMWrapper
DataMediator
Interface
PMWrapper
ProcessMediator
Interface
ChoreographyWrapper
Choreography
Interface
Reasoner Interface
Reasoner
Resource Manager Interface
WSMO Objects Non WSMO Objects
WSMT – Web Services Modeling Toolkit
Service Providers
Web Service 1
Web Service 2
Web Service p
...
Service Requesters
Back-End Application
Agent acting on behalf of service
requester
WSML EditorWSMX Monitor Ontology VisualizerWSMX Managment Mapping Tools
ComponentWrapper
New Component
Interface
OASIS Symposium 2006 77
Selected Components
• Adapters• Parser• Invoker• Choreography • Process Mediator• Discovery• Data Mediator• Resource Manager
• Reasoning E
xecu
tion
Ma
na
ge
me
nt
Ve
rtic
al S
erv
ice
s e
.g.
Se
curi
ty
Storage Reasoning
Communication (external)
Fault Handling Monitoring
Data MediationProcess
Mediation
Discovery Adaptation Composition Choreography
Application Services Layer
Problem Solving Layer
Base Services Layer
End User Tools Developer Tools
Internet
Message
MessagePeerPeer
Internet
Message
Message
OASIS Symposium 2006 78
Adapters
• To overcome data representation mismatches on the communication layer
• Transforms the format of a received message into WSML compliant format
• Based on mapping rules
OASIS Symposium 2006 79
Parser
• WSML compliant parser– Code handed over to wsmo4j initiative
http://wsmo4j.sourceforge.net/
• Validates WSML description files• Compiles WSML description into internal memory model• Stores WSML description persistently
(using Resource Manager)
OASIS Symposium 2006 80
Communication Manager – Invoker
• WSMX uses – The SOAP implementation from Apache AXIS
– The Apache Web Service Invocation Framework (WSIF)
• WSMO service descriptions are grounded to WSDL• Both RPC and Document style invocations possible• Input parameters for the Web Services are translated from WSML to
XML using an additional XML Converter component.
Network
InvokerApache
AXISXML
ConverterMediatedWSML Data
XML WebService
SOAP
OASIS Symposium 2006 81
Choreography
• Requester and provider have their own observable communication patterns– Choreography part of WSMO
• Choreography instances are loaded for the requester and provider– Both requester and provider have their own WSMO descriptions
• Choreography Engine– Evaluation of transition rules
• Prepares the available data
– Sends data to the Process Mediator• The Process Mediator filters, changed or even replaced data
– Receive data from PM and forwards it to the Communication manager
• Data to be finally sent to the communication partner
OASIS Symposium 2006 82
Process Mediator
• Requester and provider have their own communication patterns
• Only if the two match precisely, a direct communication may take place
• The Process Mediator provides the means for runtime analyses of two choreography instances and uses mediators to compensate possible mismatches
OASIS Symposium 2006 83
Discovery
• Responsible for finding appropriate Web Services to achieve a goal (discovery)
• Current discovery component is based on simple matching– Keywords identified in the NFP of the goal– Matched against NFPs of the published WSs – Variable set of NFPs to be considered for this process– To be extended
• Values in NFPs might be concepts from ontologies
• More elaborate string matching algorithms
• Advanced semantic discovery in prototypical stage
OASIS Symposium 2006 84
Data Mediator
• Ontology-to-ontology mediation
• A set of mapping rules are defined and then executed
• Initially rules are defined semi-automatic
• Create for each source instance the target instance(s)
Target Ontology
Source Ontology
Storage
Mappings
Mappings
Source Instance
Target Instance
Run-time ComponentDesign-time Component
Data Mediation
OASIS Symposium 2006 85
Resource Manager
• Stores internal memory model to a data store• Decouples storage mechanism from the rest of WSMX• Data model is compliant to WSMO API• Independent of any specific data store implementation
i.e. database and storage mechanism
OASIS Symposium 2006 86
Reasoner
• Mins – Datalog + Negation + Function
Symbols Reasoner Engine– Features
• Built-in predicates • Function symbols • Stratified negation
• WSMO4J– validation, serialization and parsing
• WSML2Reasoner– Reasoning API
• mapping fromWSML to a vendor-neutral rule representation
– Contains: • Common API for WSML Reasoners• Transformations of WSML to tool-specific input data
(query answering or instance retrieval)
• WSML-DL-Reasoner– Features:
• T-Box reasoning (provided by FaCT++) • Querying for all concepts • Querying for the equivalents, for the children, for the
descendants, for the parents and for all ancestors of a given concept
• Testing the satisfiability of a given concept with respect to the knowledge base
• Subsumption test of two concepts with respect to the knowledge base
• Wrapper of WSML-DL to the XML syntax of DL used in the DIG interface
OASIS Symposium 2006 87
System Entry Points
• achieveGoal (WSMLDocument): Context
• getWebServices (WSMLDocument): Context
invokeWebService(WSMLDocument, Context): Context
OASIS Symposium 2006 88
Define “Business” Process
OASIS Symposium 2006 89
Generate Wrappers for Components
Discovery Wrapper
ChoreographyWrapper
Communication Manager Wrapper
Registry of known components
OASIS Symposium 2006 90
Context Data
PROCESS CONTEXT
Discovery Wrapper
Data Mediator ChoreographyWrapper
Communication Manager Wrapper
Registry of known components
Choreography objectMediated objects ,
Web Services entities
ErrorsExceptions
OASIS Symposium 2006 91
Event-based Implementation
OASIS Symposium 2006 92
WSMX Conclusions
• Conceptual model is WSMO • End to end functionality for executing SWS• Has a formal execution semantics• Real implementation • Open source code base at SourceForge• Event-driven component architecture
Exe
cutio
n M
ana
gem
ent
Ver
tical
Ser
vice
s e
.g. S
ecur
ity
Storage Reasoning
Communication (external)
Fault Handling Monitoring
Data MediationProcess
Mediation
Discovery Adaptation Composition Choreography
Application Services Layer
Problem Solving Layer
Base Services Layer
End User Tools Developer Tools
Internet
Message
MessagePeerPeer
Internet
Message
Message
OASIS Symposium 2006 93
Overview
• Introduction to SWS– WSMO
• Introduction to SOA– WSMX
• Means of Interoperability• WSMT• Conclusions
OASIS Symposium 2006 94
Means of Interoperability
• Format and Language heterogeneity– Adaptors to/from WSML
• Interface/communications formalism– Choreography and Orchestraton
• Ontology heterogeneity– Data Mediation
• Interface/communication patterns heterogeneity– Process Mediation
OASIS Symposium 2006 95
Adapter Framework
• Overview– Overcomes mismatches at the communication layer– Is based on Java Connector Architecture (JCA)– Is based on SOA design principles– Adapters function independently– Adapters are built based on mapping rules– Is developed in Java
• Motivation– WSMX does not recognize message formats other than WSML– Backend applications that do not use WSML cannot
communicate with WSMX without the help of adapters that transforms the format of a received message to WSML format
– Provide a unified framework for developing and using adapters
OASIS Symposium 2006 96
Features
• Adapters can be added and removed at run time• Secure pluggability• Supports both synchronous and asynchronous
communication• Handles communication protocol heterogeneity, i.e.,
allow to communicate using HTTP(S), TCP/IP, UDP• Provides simple operations:
– Deploy: adds adapter to the adapter pool– Undeploy: removes adapter from the adapter pool, subject to
security constraints– Send: send legacy message to WSMX– Receive: receive legacy message from WSMX
OASIS Symposium 2006 97
Adapter Framework - Architecture
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
......2WSML WSML2
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2Dir
ect
Com
munic
atio
nD
irec
t C
omm
unic
atio
n
Indir
ect
Com
munic
atio
n
Metadata Repository
OASIS Symposium 2006 98
Adapter Framework – Deploy adapter
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
deploy (adapterName,
someAdaper.adapter)
Request sent to deploy an adapter
OASIS Symposium 2006 99
Adapter Framework – Deploy adapter
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
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RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
deploy (adapterName,
someAdaper.adapter)
Communication type scanned
OASIS Symposium 2006 100
Adapter Framework – Deploy adapter
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
deploy (adapterName,
someAdaper.adapter)
Fingerprint for this adapter created
OASIS Symposium 2006 101
Adapter Framework – Deploy adapter
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
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RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Metadata updated
OASIS Symposium 2006 102
Adapter Framework – Deploy adapter
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
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Man
ager
Com
munic
atio
n M
anag
er
WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
adapterName2WSML
Adapter stored
OASIS Symposium 2006 103
Adapter Framework – Deploy adapter
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
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l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Fingerprint returned in a requested communication mode
OASIS Symposium 2006 104
Adapter Framework – Deploy adapter
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Fingerprint returned in to backend application
D749 9163 9E5E BDFC 8018 E6B8 49DD 3252 ACF6
7294
OASIS Symposium 2006 105
Adapter Framework – Send
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Message send to WSMX via Adapter Framework
send (adapterName, message, fingerprint)
OASIS Symposium 2006 106
Adapter Framework – Send
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Communication type scanned
send (adapterName, message, fingerprint)
OASIS Symposium 2006 107
Adapter Framework – Send
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Fingerprint checked, valid fingerprint
send (adapterName, message, fingerprint)
OASIS Symposium 2006 108
Adapter Framework – Send
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Message format checked, valid fingerprint
send (adapterName, message, fingerprint)
OASIS Symposium 2006 109
Adapter Framework – Send
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Internal request sent to select adapterName2WSML
send (adapterName, message, fingerprint)
OASIS Symposium 2006 110
Adapter Framework – Send
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
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atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
adapterName2WSML selected looking into metadata repository
send (adapterName, message, fingerprint)
OASIS Symposium 2006 111
Adapter Framework – Send
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Message translated and sent to WSMX
achieveGoal (WSMLDocument)
OASIS Symposium 2006 112
Adapter Framework – Undeploy adapter
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Request sent to undeploy an adapter together with its fingerprint
undeploy (adapterName, D749
9163 9E5E BDFC 8018 E6B8 49DD 3252 ACF6
7294)
OASIS Symposium 2006 113
Adapter Framework – Undeploy adapter
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Fingerprint checked, valid fingerprint
undeploy (adapterName, D749
9163 9E5E BDFC 8018 E6B8 49DD 3252 ACF6
7294)
OASIS Symposium 2006 114
Adapter Framework – Undeploy adapter
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
toco
l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
adapterName2WSML WSML2adapterName
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Metadata updated
OASIS Symposium 2006 115
Adapter Framework – Undeploy adapter
Bac
ken
d
Applica
tion
WSM
X
Lis
tener
Pro
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l Han
dle
r (S
ync,
Asy
nc)
Secu
rity
Man
ager
Com
munic
atio
n M
anag
er
RosettaNet2WSML WSML2RosettaNet
EDI2WSML WSML2EDI
UBL2WSML WSML2UBL
Inward Outward
Adapter Pool
Adapter Manager/ Selector
Validator (Message, Protocol)
... .........
...
...
2WSML
2WSML
2WSML
WSML2
WSML2
WSML2
Metadata Repository
Adapter removed
10 May 2006 OASIS Symposium 2006
VTAService
Date
Time
Flight, Hotel
Error
Confirmation
Hotel Service
Flight Service
Date, Time
Hotel
Error
Date, Time
Flight
Error
When the service is requested
When the service requests
Choreography & Orchestration
VTA example:
• Choreography = how to interact with the service to consume its functionality • Orchestration = how service functionality is achieved by aggregating other Web
services
Confirmation
Confirmation
10 May 2006 OASIS Symposium 2006
Abstract State Machine
• Formality – a rigid framework to express dynamics.
• Maximality – expressive enough to model any aspect around computation
• Minimality – minimal set of modeling primitives – minimal ontological
commitment
10 May 2006 OASIS Symposium 2006
Choreography outline
• NFPs – The same as in WSML
• State Signature– Defines the state ontology used by the service together with the
definition of the types of modes the concepts and relations may have
• Transition Rules– Express changes of states
Class choreography hasNonFunctionalProperties type nonFunctionalProperties
hasStateSignature type stateSignature
hasTransitionRules type transitionRules
10 May 2006 OASIS Symposium 2006
States Signatures
Class stateSignature
hasNonFunctionalProperties type nonFunctionalProperties
importsOntology type ontology
usesMediator type ooMediator
hasStatic type mode
hasIn type mode
hasOut type mode
hasShared type mode
hasControlled type mode
Class mode subClass {concept, relation}
hasGrounding type grounding
10 May 2006 OASIS Symposium 2006
Transition Rules
• if φ then T endIf• forall V with ψ do T′ endForall• choose V with ψ do T′ endChoose
• φ is a first order formula with no free variables• V is a set of variables• ψ is a first order formula where the free variables are interpreted as
parameters and all free variables in ψ occur in V• T is a set of transition rules• T′ is a set of transition rules and/or non-ground update rules, where
each variable which occurs in any non-ground update rule in T′, occurs also in V
10 May 2006 OASIS Symposium 2006
Update rules
• add(a)• delete(a)
where a is a WSML atomic formula, which possibly includes – parameter variables, or – non-primitive update rules of the form:
• update(anew)• update(aold => anew)
• SU = S \ {a|delete(a) Є U} U {a|add(a) Є U}
where O is an ontology O, S a state and U an update set
10 May 2006 OASIS Symposium 2006
Machine behaviour
Given C = (O, T, S)
• S0 = S
• for 0 ≤ i ≤ n-1,– Si ≠ Si+1
– U = {add(a) | a Є Si+1 \ Si} U {delete(a) | a Є Si \ Si+1} is an update set associated with Si, O and T
– Si+1 is consistent with O, and Si
• run terminated
OASIS Symposium 2006 123
Data Mediator
• Ontology-to-ontology mediation
• A set of mapping rules are defined and then executed
• Initially rules are defined semi-automatic
• Create for each source instance the target instance(s)
Target Ontology
Source Ontology
Storage
Mappings
Mappings
Source Instance
Target Instance
Run-time ComponentDesign-time Component
Data Mediation
OASIS Symposium 2006 124
Design-time
• Inputs– Source Ontology and Target Ontology
• Features– Graphical interface– Set of mechanism towards semi-automatic creation of mappings– Capturing the semantic relationships identified in the process– Storing these mappings in a persistent storage
• Output– Abstract representation of the mappings
OASIS Symposium 2006 125
Design-time Phase
OASIS Symposium 2006 126
Design-time Phase - Approach, Decomposition and Mapping Context
• Bottom-up -> training set• Top-down -> decomposition, context
OASIS Symposium 2006 127
Design-time Phase - Suggestion Algorithms
• Eligibility Factor = f(Lexical Factor, Structural Factor)
• Lexical Factor:– WordNet
• Synonyms, hyponyms, hipernyms
– string analyzing algorithms• Tokenizer and string distance
• Structural Factor– Decomposition, EF for the composing concepts
• Based on the already done mappings
OASIS Symposium 2006 128
Run-Time Data Mediator
• Main Mediation Scenario: Instance Transformation
• Inputs– Incoming data
• Source ontology instances
• Features– Completely automatic process– Grounding of the abstract mappings to a concrete language
• F-Logic, WSML
– Uses a reasoner to evaluate the mapping rules• MINS
• Outputs– Mediated data
• Target ontology instances
OASIS Symposium 2006 129
Run Time Component - Architecture
Abstract Mappings
Repr.
RulesGenerator
Instance
Source
ReasoningEnvironment
Mapping Rules
Mappings
Instance
Target
Ontologies
OASIS Symposium 2006 130
Run Time Component – Features
• Grounding the abstract mappings• Associate a formal semantics to the mappings
– Obtain rules in a concrete language
• Why not during design time?– Offers a grater flexibility– Different groundings for the same mappings set– Different execution environments for the grounded mappings– Easier to maintain the abstract mappings– Important point of alignment
• Caching mechanism can be used
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Ontology Mapping Language
• Language Neutral Mapping Language – mapping definitions on meta-layer (i.e. on generic ontological constructs) – independent of ontology specification language – “Grounding” to specific languages for execution (WSML, OWL, F-Logic)
• Main Features: – Mapping Document (sources, mappings, mediation service) – direction of mapping (uni- / bidirectional) – conditions / logical expressions for data type mismatch handling, restriction of
mapping validity, and complex mapping definitions – mapping constructs:
• classMapping, attributeMapping, relationMapping (between similar constructs) • classAtrributeMapping, classRelationMapping, classInstanceMapping• instanceMapping (explicit ontology instance transformation)
– mapping operators: • =, <, <=, >, >=, and, or, not • inverse, symmetric, transitive, reflexive • join, split
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Ontology O2
Mapping Language Example
Human - name
Adult Child
Person- name - age
mick memberOf Person- name = Mick Kerrigan- age = 27
classMapping(unidirectional o2:Person o1.Adult attributeValueCondition(o2.Person.age >= 18))
This allows to transform the instance ‘mick’ of concept person in ontology O2 into a valid instance of concept ‘adult’ in ontology O1
Ontology O1
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Process Mediator
• Requester and provider have their own communication patterns
• Only if the two match precisely, a direct communication may take place
• The Process Mediator provides the means for runtime analyses of two choreography instances and uses mediators to compensate possible mismatches
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Compatibility
• Two business partners are compatible if their public processes are matching
Business Partner1
Business Partner2
A
B
C
D
E
A
B
C
D
E
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Compatibility
• Two business partners are compatible if their public processes are matching
Business Partner1
Business Partner2
A
B
C
D
E
E
B
C, D
A
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Process Mediator – Addressed Mismatches
Business Partner1Business Partner1
Business Partner2Business A
B B
Business Partner1Business Partner1
Business Partner2Business Partner2
A B
B A
Business Partner1Business Partner1
Business Partner2Business Partner2
A and BA
B
Business Partner1Business Partner1
Business Partner2Business Partner2
A
BA and B
PM
PM
PM
PM
Business Partner1Business Partner1
Business Partner2Business Partner2
A
AckA
APM
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Process Mediator – Unsolvable Mismatches
Business Partner1Business Partner1
Business Partner2Business
A
Business Partner1Business Partner1
Business Partner2Business Partner2
A B
B A
Business Partner1Business Partner1
Business Partner2Business Partner2
PM
PM
PM
A
Ack
?
?
?
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itinerary[origin, destination, date]
time
price
origin
destination
itinerary[origin, destination]
date
ticket[route,date, time, price]
REQUEST
SERVICE
Processes Mediator
Process Mediation Example
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time
pricedate
REQUEST
SERVICE
Processes Mediator
Process Mediation Example
itinerary[origin, destination, date]
origin
destination
itinerary[origin, destination]
ticket[route,date, time, price]
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time
pricedate
REQUEST
SERVICE
Processes Mediator
Process Mediation Example
itinerary[origin, destination, date]
origin
destination
itinerary[origin, destination]
ticket[route,date, time, price]
OASIS Symposium 2006 141
time
pricedate
REQUEST
SERVICE
Processes Mediator
itinerary[origin, destination, date]
origin
destination
itinerary[origin, destination]
ticket[route,date, time, price]
Process Mediation Example
OASIS Symposium 2006 142
time
pricedate
REQUEST
SERVICE
Processes Mediator
itinerary[origin, destination, date]
origin
destination
itinerary[origin, destination]
ticket[route,date, time, price]
Process Mediation Example
OASIS Symposium 2006 143
Overview
• Introduction to SWS– WSMO
• Introduction to SOA– WSMX
• Means of Interoperability• WSMT• Conclusions
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Web Services Modeling Toolkit
• The aim of the Web Services Modeling Toolkit (WSMT) is to provide high-quality tools for designing, mediating and using Semantic Web Services, through the WSMO paradigm.
• The focus is currently on the following areas:– Creation of ontologies, web services, goals and mediators in
WSMO– Creation of mappings between pairs of ontologies to allow
runtime instance transformation– Management of Execution Environments for Semantic Web
Services like WSMX and IRSIII
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WSML Perspective
• Perspectives in the Eclipse framework allow for a number of Editors and views to be grouped and positions.
• The WSML perspective offers editors and views related to engineering of semantic descriptions in WSMO through the WSML language.
• Other General features include:– WSML file validation– Problems view (errors and warnings on files in the workspace)– Label highlighting (marking of errors and warnings in navigator
view)
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WSML Editors and Views in the WSML perspective
EditorsWSML Text Editor
WSML Conceptual Editor
WSML Visualizer
ViewsNavigator view
Problems view
WSML Reasoner
OASIS Symposium 2006 147
Editors and Views in the WSML perspective
EditorsWSML Text Editor
WSML Conceptual Editor
WSML Visualizer
ViewsNavigator view
Problems view
WSML Reasoner
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Editors and Views in the WSML perspective
EditorsWSML Text Editor
WSML Conceptual Editor
WSML Visualizer
ViewsNavigator view
Problems view
WSML Reasoner
OASIS Symposium 2006 149
Editors and Views in the WSML perspective
EditorsWSML Text Editor
WSML Conceptual Editor
WSML Visualizer
ViewsNavigator view
Problems view
WSML Reasoner
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Editors and Views in the WSML perspective
EditorsWSML Text Editor
WSML Conceptual Editor
WSML Visualizer
ViewsNavigator view
Problems view
WSML Reasoner
OASIS Symposium 2006 151
Editors and Views in the WSML perspective
EditorsWSML Text Editor
WSML Conceptual Editor
WSML Visualizer
ViewsNavigator view
Problems view
WSML Reasoner
OASIS Symposium 2006 152
Editors and Views in the WSML perspective
EditorsWSML Text Editor
WSML Conceptual Editor
WSML Visualizer
ViewsNavigator view
Problems view
WSML Reasoner
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Editors, Views for the Abstract Mapping Language
EditorsAML Text Editor
AML Conceptual Editor
AML View Based Editor
ViewsConcept 2 Concept View
Attribute 2 Attribute View
Concept 2 Attribute View
Attribute 2 Concept View
Status View
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Editors, Views for the Abstract Mapping Language
EditorsAML Text Editor
AML Conceptual Editor
AML View Based Editor
ViewsConcept 2 Concept View
Attribute 2 Attribute View
Concept 2 Attribute View
Attribute 2 Concept View
Status View
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Editors, Views for the Abstract Mapping Language
EditorsAML Text Editor
AML Conceptual Editor
AML View Based Editor
ViewsConcept 2 Concept View
Attribute 2 Attribute View
Concept 2 Attribute View
Attribute 2 Concept View
Status View
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Editors, Views for the Abstract Mapping Language
EditorsAML Text Editor
AML Conceptual Editor
AML View Based Editor
ViewsConcept 2 Concept View
Attribute 2 Attribute View
Concept 2 Attribute View
Attribute 2 Concept View
Status View
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Editors, Views for the Abstract Mapping Language
EditorsAML Text Editor
AML Conceptual Editor
AML View Based Editor
ViewsConcept 2 Concept View
Attribute 2 Attribute View
Concept 2 Attribute View
Attribute 2 Concept View
Status View
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Editors, Views for the Abstract Mapping Language
EditorsAML Text Editor
AML Conceptual Editor
AML View Based Editor
ViewsConcept 2 Concept View
Attribute 2 Attribute View
Concept 2 Attribute View
Attribute 2 Concept View
Status View
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Editors, Views for the Abstract Mapping Language
EditorsAML Text Editor
AML Conceptual Editor
AML View Based Editor
ViewsConcept 2 Concept View
Attribute 2 Attribute View
Concept 2 Attribute View
Attribute 2 Concept View
Status View
OASIS Symposium 2006 160
Editors, Views for the Abstract Mapping Language
EditorsAML Text Editor
AML Conceptual Editor
AML View Based Editor
ViewsConcept 2 Concept View
Attribute 2 Attribute View
Concept 2 Attribute View
Attribute 2 Concept View
Status View
OASIS Symposium 2006 161
Overview
• Introduction to SWS– WSMO
• Introduction to SOA– WSMX
• Means of Interoperability• WSMT• Conclusions
OASIS Symposium 2006 162
Conclusions
• Semantic Enabled SOA combines the benefits of semantics with best practices from industry
• WSMO - conceptual model for Semantic Web Services – Ontology of core elements for Semantic Web Services
• Clear separation between layers– Specification and realization– Interface and implementation
• WSMX/SEE – a Semantic Enabled SOA– Service Oriented Architecture– Reference implementation of WSMO
• Semantic Enabled SOA offers multiple means for interoperability– Mediation framework– Interface/communication disambiguation
• WSMT – emerging tool to handle semantics– High-quality tools for designing, mediating and using Semantic Web
Services
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References
• The central location where WSMO work and papers can be found is WSMO Working Group: http://www.wsmo.org
• WSMO languages – WSML Working Group: http://www.wsml.org
• WSMO implementation – WSMX working group : http://www.wsmx.org– WSMX open source can be found at: https://sourceforge.net/projects/wsmx/
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References
• [WSMO Specification]: Roman, D.; Lausen, H.; Keller, U. (eds.): Web Service Modeling Ontology, WSMO Working Draft D2, final version 1.2, 13 April 2005.
• [WSMO Primer]: Feier, C. (ed.): WSMO Primer, WSMO Working Draft D3.1, 18 February 2005.
• [WSMO Choreography and Orchestration] Roman, D.; Scicluna, J., Feier, C. (eds.): Ontology-based Choreography and Orchestration of WSMO Services, WSMO Working Draft D14, 01 March 2005.
• [WSMO Use Case] Stollberg, M.; Lausen, H.; Polleres, A.; Lara, R. (ed.): WSMO Use Case Modeling and Testing, WSMO Working Drafts D3.2; D3.3.; D3.4; D3.5, 05 November 2004.
• [WSML] de Bruijn, J. (Ed.): The WSML Specification, WSML Working Draft D16, 03 February 2005.
• [Arroyo et al. 2004] Arroyo, S., Lara, R., Gomez, J. M., Berka, D., Ding, Y. and Fensel, D: "Semantic Aspects of Web Services" in Practical Handbook of Internet Computing. Munindar P. Singh, editor. Chapman Hall and CRC Press, Baton Rouge. 2004.
• [Berners-Lee et al. 2001] Tim Berners-Lee, James Hendler, and Ora Lassila, “The Semantic Web”. Scientific American, 284(5):34-43, 2001.
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References
• [Bussler, 2003] Bussler, C. (2003): B2B Integration. Berlin, Heidelberg: Springer.
• [Cimpian and Mocan, 2005] Emilia Cimpian, Adrian Mocan: WSMX Process Mediation Based on Choreographies, 1st International Workshop on Web Service Choreography and Orchestration for Business Process Management (BPM 2005), September 2005, Nancy, France
• [Chen et al., 1993] Chen, W., Kifer, M., and Warren, D. S. (1993). HILOG: A foundation for higher-order logic programming. Journal of Logic Programming, 15(3):187-230.
• [Haller et al., 2005] A. Haller, E. Cimpian, A. Mocan, E. Oren, and C. Bussler. WSMX - A Semantic Service-Oriented Architecture. International Conference on Web Services (ICWS 2005), July 2005.
• [Kerrigan, 2006] Mick Kerrigan: Web Service Selection Mechanisms in the Web Service Execution Environment (WSMX), Proceedings of the 21st Annual ACM Symposium on Applied Computing (SAC), April, 2006, Dijon, France
• [Mandell and McIIraith, 2003] Daniel J. Mandell and Sheila A. McIlraith. Adapting BPEL4WS for the Semantic Web: The Bottom-Up Approach to Web Service Interoperation. In Proceedings of the Second International Semantic Web Conference (ISWC2003)
• [Mocan and Cimpian, 2005] Adrian Mocan, Emilia Cimpian: Mapping Creation Using a View Based Approach, 1st International Workshop on Mediation in Semantic Web Services (Mediate 2005), December 2005, Amsterdam, Netherlands
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References
• [Domingue et al., 2004] Domingue, J. Cabral, L., Hakimpour, F., Sell D., and Motta, E., (2004) IRS-III: A Platform and Infrastructure for Creating WSMO-based Semantic Web Services WSMO Implementation Workshop (WIW), Frankfurt, Germany, September,2004
• [Feier et al., 2005] C. Feier, A. Polleres, R. Dumitru, J. Domingue, M. Stollberg, and D. Fensel. Towards intelligent web services: The web service modeling ontology (WSMO). International Conference on Intelligent Computing (ICIC), April 2005.
• [Fensel, 2001] Dieter Fensel, “Ontologies: Silver Bullet for Knowledge Management and Electronic Commerce”, Springer-Verlag, Berlin, 2001.
• [Fensel and Bussler, 2002] Fensel D. and Bussler C., "The Web Service Modeling Framework, WSMF," Electronic Commerce Research and Application, vol. 1, 2002
• [Fensel, 2004] D. Fensel: Triple Space computing - Semantic Web Services based on persistent publication of information. In Proceedings of IFIP International Conference on Intelligence in Communication Systems, Pages 43-53, Bangkok, Thailand, November 2004.
• [Gruber, 1993] Thomas R. Gruber, “A Translation Approach to Portable Ontology Specifications”, Knowledge Acquisition, 5:199-220, 1993.
• [Grosof et al., 2003] Grosof, B. N., Horrocks, I., Volz, R., and Decker, S. (2003). Description logic programs: Combining logic programs with description logic. In Proc. Intl. Conf. on the World Wide Web (WWW-2003), Budapest, Hungary.
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References
• [Haselwanter et al., 2005] Haselwanter, T.; Zaremba, Ma.., Zaremba Mi.: Enabling Components Management and Executions Semantics in WSMX. In Proceedings of the 2nd International WSMO Implementation Workshop (WIW 2005), Innsbruck, Austria, June 2005.
• [Keller et al., 2004] Keller, U.; Lara, R.; Polleres, A. (Eds): WSMO Web Service Discovery. WSML Working Draft D5.1, 12 Nov 2004.
• [Keller et al., 2005] Keller, U.; Lara, R.; Lausen, H.; Polleres, A.; Fensel, D.: Automatic Location of Services. In Proc. of the 2nd European Semantic Web Symposium (ESWS2005), Heraklion, Crete, 2005.
• [Kifer et al., 1995] Kifer, M., Lausen, G., and Wu, J. (1995). Logical foundations of object-oriented and frame-based languages. JACM, 42(4):741-843.
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• [Li and Horrocks, 2003] Lei Li and Ian Horrocks. A software framework for matchmaking based on semantic web technology. In Proc. of the Twelfth International World Wide Web Conference (WWW 2003), 2003
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References
• [Pan and Horrocks, 2004] Pan, J. Z. and Horrocks, I. (2004). OWL-E: Extending OWL with expressive datatype expressions. IMG Technical Report IMG/2004/KR-SW-01/v1.0, Victoria University of Manchester. Available from http://dl-web.man.ac.uk/Doc/IMGTR-OWL-E.pdf.
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Acknowledgements
We would like to thank to all the members of the WSMO, WSML, and WSMX working groups for their advice and input into this tutorial.
The WSMO working groups are funded by the European Commission under the projects ASG, DIP, Knowledge Web, SEKT, SemanticGov, SWWS, AKT and Esperonto; by Science Foundation Ireland under the DERI-Lion project; and by the Austrian government under the FIT-IT program