kmi.open.ac.uk Semantic Execution Environments Service Engineering and Execution Barry Norton and Mick Kerrigan
kmi.open.ac.uk
Semantic Execution Environments
Service Engineering and Execution
Barry Norton and Mick Kerrigan
kmi.open.ac.uk
Plan for the Day
• Review and reinforcement of WSMO model for services
and Semantic SOA Reference Ontology
• Semantic Execution Environment (SEE) Reference Architecture
• Semantic Web Service Engineering Scenarios
• Web Service Modelling Toolkit (WSMT)
• Hands-on with SEE and WSMT
• The Future for Service Engineering
2
kmi.open.ac.uk
Plan for the Day
• Review and reinforcement of WSMO model for services
and Semantic SOA Reference Ontology
• Semantic Execution Environment (SEE) Reference Architecture
• Semantic Web Service Engineering Scenarios
• Web Service Modelling Toolkit (WSMT)
• Hands-on with SEE and WSMT
• The Future for Service Engineering
3
kmi.open.ac.uk
Web Service Description
• WSMO Web Services describe abilities of deployed services…
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
Web Service
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Web Service Description
• Their Capabilities describe their functional abilities…
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
Web Service
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Web Service Description
• Preconditions express guarantees they expect from clients, purely over information they communicate…
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
Web Service
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Web Service Description
• Assumptions express general guarantees they expect of clients, involving the environment outside communications…
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
Web Service
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Web Service Description
• Postconditions express guarantees they make over information communicated back, providing the preconditions and assumptions are met by the client…
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
Web Service
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Web Service Description
• Effects express the general guarantees made, outside information directly communicated, providing the preconditions and assumptions are met by the client
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
Web Service
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Web Service Description
• The interfaces of web services describe their behavioural characteristics, i.e. the communications they engage in
Capability
InterfaceChoreography
Orchestration
State Signature
Transition Rules
Web Service
PreconditionAssumption
Postcondition
Effect
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Web Service Description
• The choreography expresses communications the service engages in with its clients…
Capability
InterfaceChoreography
Orchestration
State Signature
Transition Rules
Web Service
PreconditionAssumption
Postcondition
Effect
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Web Service Description
• The state signature describes these communications semantically, by linking modes to ontological concepts
Capability
InterfaceChoreography
Orchestration
State Signature
Transition Rules
Web Service
PreconditionAssumption
Postcondition
Effect
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Web Service Description
• The state signature describes these communications semantically, by linking modes to ontological concepts:
– IN modes describe communications the service is able to receive
Capability
InterfaceChoreography
Orchestration
State Signature
Transition Rules
Web Service
PreconditionAssumption
Postcondition
Effect
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Web Service Description
• The state signature describes these communications semantically, by linking modes to ontological concepts:
– IN modes describe communications the client would like to receive;– OUT modes describe communications the service is able to send
Capability
InterfaceChoreography
Orchestration
State Signature
Transition Rules
Web Service
PreconditionAssumption
Postcondition
Effect
14
kmi.open.ac.uk
Web Service Description
• The state signature describes these communications semantically, by linking modes to ontological concepts:
– IN modes describe communications the client would like to receive;– OUT modes describe communications the service is able to send;– modes may be grounded to physical communications, most usually WSDL messages
but also REST resource methods, and in the IRS LISP and Java functions.
Capability
InterfaceChoreography
Orchestration
State Signature
Transition Rules
Web Service
PreconditionAssumption
Postcondition
Effect
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Web Service Description
• Transition rules link communications into a stateful interaction
Capability
InterfaceChoreography
Orchestration
State Signature
Transition Rules
Web Service
PreconditionAssumption
Postcondition
Effect
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Web Service Description
• Transition rules link communications into a stateful interaction:– Transition rules may be used in matching and (process) mediation against goals,
Capability
InterfaceChoreography
Orchestration
State Signature
Transition Rules
Web Service
PreconditionAssumption
Postcondition
Effect
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Web Service Description
• Transition rules link communications into a stateful interaction:– Transition rules may be used in matching and (process) mediation against goals, or
for – In process mediation between IRS-III/WSMX broker and the deployed service
Capability
InterfaceChoreography
Orchestration
State Signature
Transition Rules
Web Service
PreconditionAssumption
Postcondition
Effect
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Web Service Description
• Orchestrations describe how composite services achieve their behaviour in terms of communications between its components, which may be goals or services, together with mediators.
Capability
InterfaceChoreography
Orchestration
State Signature
Transition Rules
Web Service
PreconditionAssumption
Postcondition
Effect
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Goal Description
• Goals describe requirements from client perspective…
Goal
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
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Goal Description
• Their Capabilities describe the functional requirements…
Goal
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
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Goal Description
• Preconditions express guarantees client can make, purely over information they can communicate, in order that functional requirements are met…
Goal
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
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Goal Description
• Assumptions express general guarantees client can make, involving the environment, in order that functional requirements are met…
Goal
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
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Goal Description
• Postconditions express guarantees client would like over information communicated back in order that functional requirements are met…
Goal
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
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Goal Description
• Effects express the general guarantees the client would like after the goal has been achieved
Goal
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
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Goal Description
• Capabilities can be used for one or more of: representing a client-oriented perspective, advertising and service discovery.
Goal
Capability
Interface
PreconditionAssumption
Postcondition
Effect
Choreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
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Goal Description
• The interfaces of goals describe the behavioural requirements of clients, i.e. constraints over communication
Goal
Capability
InterfaceChoreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
PreconditionAssumption
Postcondition
Effect
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Goal Description
• The choreography expresses communications the client is able to engage in…
Goal
InterfaceChoreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
Capability
PreconditionAssumption
Postcondition
Effect
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Goal Description
Goal
InterfaceChoreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
• The state signature describes these communications semantically, by linking modes to ontological concepts
Capability
PreconditionAssumption
Postcondition
Effect
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Goal Description
• The state signature describes these communications semantically, by linking modes to ontological concepts:
– IN modes describe communications the client would like to receive
Goal
InterfaceChoreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
Capability
PreconditionAssumption
Postcondition
Effect
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Goal Description
• The state signature describes these communications semantically, by linking modes to ontological concepts:
– IN modes describe communications the client would like to receive;– OUT modes describe communications the client is able to send.
Goal
InterfaceChoreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
Capability
PreconditionAssumption
Postcondition
Effect
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Goal Description
Goal
InterfaceChoreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
• Transition rules link communications into a stateful interaction
Capability
PreconditionAssumption
Postcondition
Effect
32
kmi.open.ac.uk
Goal Description
Goal
InterfaceChoreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
• Transition rules link communications into a stateful interaction:– Transition rules can be used to constrain the stateful behaviour of matching services,
or be used in process mediation should the goal be linked to a service which is not directly behaviourally compatible.
Capability
PreconditionAssumption
Postcondition
Effect
33
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Goal Description
Goal
InterfaceChoreography
Orchestration
State Signature
Transition Rules
State Signature
Transition Rules
• Orchestrations govern over the composite behaviour that is required to go into meeting the goal – the technology to exploit this is not yet available
Capability
PreconditionAssumption
Postcondition
Effect
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Web Service Description
• WG-Mediators describe which goals are met by a web service
WG-Mediator Mediation Service
OO-Mediator
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Mediation Goal
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Web Service Description
• WG-Mediators describe which goals are met by a web service;• the descriptions may have some mismatch to be mediated
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WG-Mediator Mediation Service
OO-Mediator
Mediation Goal
kmi.open.ac.uk
Web Service Description
• WG-Mediators describe which goals are met by a web service;• the descriptions may have some mismatch to be mediated:
– an oo-mediator may be supported by mapping rules between dissimilar ontologies
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WG-Mediator Mediation Service
OO-Mediator
Mediation Goal
kmi.open.ac.uk
Web Service Description
• WG-Mediators describe which goals are met by a web service;• the descriptions may have some mismatch to be mediated:
– an oo-mediator may be supported by mapping rules between dissimilar ontologies;– a mediation service identifies a web service capable of resolving the mismatch
38
WG-Mediator Mediation Service
OO-Mediator
Mediation Goal
kmi.open.ac.uk
Web Service Description
• WG-Mediators describe which goals are met by a web service;• the descriptions may have some mismatch to be mediated:
– an oo-mediator may be supported by mapping rules between dissimilar ontologies;– a mediation service identifies a web service capable of resolving the mismatch;– a mediation goal describes the capability of resolving the mismatch without identifying
a web service (in which case discovery might be recursively applied)
39
WG-Mediator Mediation Service
OO-Mediator
Mediation Goal
kmi.open.ac.uk
Plan for the Day
• Review and reinforcement of WSMO model for services
and Semantic SOA Reference Ontology
• Semantic Execution Environment (SEE) Reference Architecture
• Semantic Web Service Engineering Scenarios
• Web Service Modelling Toolkit (WSMT)
• Hands-on with SEE and WSMT
• The Future for Service Engineering
40
kmi.open.ac.uk
WSMO, WSML and WSMX
Conceptual Model for SWS
Ontology & Rule Language for the Semantic Web with built-in
support for WSMO
Semantic Execution Environment
41
kmi.open.ac.uk
WSMO, WSML and SEE
Conceptual Model for SWS
Ontology & Rule Languages Semantic Execution Environments
OWL, OCML, SWRL etc.
42
kmi.open.ac.uk
WSMO, WSML and SEE
Conceptual Model for SWS
Ontology & Rule Languages Semantic Execution Environments and
independent broker services
OWL, OCML, SWRL etc.
43
Glue 2
kmi.open.ac.uk
Semantic Execution (Developing) Standards
Conceptual Model for SWS
Ontology & Rule Language for the Semantic Web with built-in
support for WSMO
Semantic SOAReference Ontology
SEEReference Architecture
44
Glue 2Semantic Execution Environments and
independent broker services
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Semantic SOA Reference Ontology
Objectives that a client wants to achieve
Formally specified terminology used by all other components
Semantic description of Services, which advertise and allow access to capabilities: - Capability description (functional description of capability)- Interfaces (usage via service)
Connectors between components with mediation facilities for handling heterogeneities
SOAReference Model
http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=semantic-ex
Aligned with
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WSDL/SOAP Web Services
Web ServiceWeb
Service
WSDLWSDL
Describes Service
Service Consumer
Service Consumer
FindsServices
UDDIRegistry
UDDIRegistry
Points to Description
Points toService
Communicate withXML Messages
SOAPSOAP
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Semantic Web Services
Web ServiceWeb
Service
Communicate withXML Messages
SOAPSOAP
47
WSDLWSDL
Describes Service
SemanticWeb
Service
SemanticWeb
Service
Service Consumer
Service Consumer
SemanticGoal
SemanticGoal
Describes Requirements
SemanticExecution
Environment
SemanticExecution
Environment
SWSRegistry
SWSRegistry
Published to
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Service Oriented Architecture
48
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
ServiceWeb
ServiceWeb
ServiceWeb ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service Web ServiceWeb
Service
CustomApplication
CustomApplication
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Semantically Enabled SOA
49
Semantic Execution Environment
Semantic Execution Environment
DiscoveryDiscovery Ranking &SelectionRanking &Selection CompositionComposition
MediationMediation Grounding &Invocation
Grounding &Invocation
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
ServiceWeb
ServiceWeb
ServiceWeb ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service
Web ServiceWeb
Service Web ServiceWeb
Service
GoalGoal
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SEE Reference Architecture
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SEE Reference Architecture
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• Base services, providing storage and reasoning support, underlie all broker services
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SEE Reference Architecture
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• Vertical services are invoked by both base and broker services• Their purpose is orthogonal to the individual purposes of the other
services
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SEE Reference Architecture
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• Broker services are otherwise independent and atomic behaviours expected of a SEE
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SEE Reference Architecture
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• Composite services may also be formed over these broker services to meet requester-oriented needs
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Reference Architecture Base Services
Storage:
‘create/retrieve/update/delete’ (CRUD) operations on:
• ontological definitions;• goal descriptions;• service descriptions;• mediator descriptions;• mapping documents.
Reasoning:
Accepts logical expressions as queries and assertions over both ontological definitions and service-related descriptions.
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Reference Architecture Vertical Services
Monitoring:
Each core SEE service is associated with concepts in an events ontology
When invoked, services may raise events of the appropriate concepts at various points during the behaviour, such as:
• commencement; • completion;• exceptional conditions.
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Reference Architecture Broker Services
Discovery:
Concerns finding services that meet a given goal.
Ranking:
Involves ordering candidate services according to how well they meet a goal.
Selection:
Provides automated means by which candidate services may be discounted
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Discovery
• Find Semantic Web Services that can totally or partial fulfil the end users Goal
GoalDescription
GoalDescription
DiscoveryService
DiscoveryService
SWSRegistry
SWSRegistry
Web ServiceDescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescription
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Discovery
G WS
Exact Match
WSGPlug-in Match
G WSSubsumption Match
G WS
Intersection Match
G WS
No Match
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Ranking
• Ordering candidate Web Services according to the match to the goal
• A particularly useful form of ranking is based on non-functional requirements
GoalDescription
GoalDescription
RankingServiceRankingService
Web ServiceDescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescription
Web ServiceDescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescription
1
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Quality of Service Aspects
• 16 ontologies have been recommended for modeling WSMO
Non-functional aspects of Web services
61
LocativeOntologyLocativeOntology
TemporalOntologyTemporalOntology
AvailabilityOntology
AvailabilityOntology
ObligationOntology
ObligationOntology
PriceOntology
PriceOntology
PaymentOntologyPaymentOntology
DiscountsOntologyDiscountsOntology
RightsOntology
RightsOntology
TrustOntology
TrustOntology
Quality of Service
Ontology
Quality of Service
Ontology
SecurityOntologySecurity
Ontology
IntellectualPropertyOntology
IntellectualPropertyOntology
RewardsOntologyRewardsOntology
ProviderOntologyProviderOntology
MeasuresOntologyMeasuresOntology
CurrencyOntologyCurrencyOntology
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Selection
• Choosing, or narrowing the choice among, the most appropriate Web Service(s) to the goal
• This may simply be based on ranking but may also take into account instance data where the goal is generic
GoalDescription
GoalDescription
SelectionService
SelectionService
Web ServiceDescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescription
Web ServiceDescriptionWeb ServiceDescription
Instance Data
Instance Data
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Reference Architecture Broker Services
Composition:
Concerns forming an orchestrated service to meet a given goal.
Data Mediation:
Transforms instances from a representation in one ontology to another.
Process Mediation:
Creates an executable process model that resolves inconsistencies between two otherwise incompatible processes.
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Composition
• Combine a number of Semantic Web Services together to fulfil the end users Goal
GoalDescription
GoalDescription
CompositionService
CompositionService
Web ServiceDescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescription
Composite Web ServiceDescription
Composite Web ServiceDescription
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Composition
• Composed Web Service descriptions advertise services that are realized through the execution of other services
• Orchestration specifies how to invoke these other services to fulfill the advertised functionality
65
Web ServiceWeb Service
Web ServiceWeb Service
Web ServiceWeb Service
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Data Mediation
• Data Mediation in general concerns resolving terminological mismatches and enabling interoperability at the data level via:
– Ontology Merging– Ontology Alignment– Instance Transformation
• As a service data mediation effects the latter of these aspects
Data MediationService
Data MediationService
Web ServiceDescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescriptionOntology InstancesOntology Instances
Web ServiceDescriptionWeb ServiceDescriptionWeb Service
DescriptionWeb ServiceDescriptionOntology InstancesOntology Instances
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Process Mediation
• Process Mediation for resolving communication mismatches, establishing behavioural compatibility and allowing interoperability at the process level
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Reference Architecture Broker Services
Process Execution:
Involves interpreting a process model and, at each step, producing the conceptual communications produced or allowed.
Lifting & Lowering:
Respectively:• Produces the conceptual representation of a web service communication (for instance a SOAP message);• Produces a web service communication corresponding to its conceptual representation.
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Reference Architecture Composite Services
At an internal level broker services are composed to form services such as:
Choreography-based execution:
Given a goal and a service description:• if the choreographies are directly compatible then the service choreography is executed;• if there exist mismatches then process mediation is applied and the resulting process is executed.
Orchestration-driven execution:
Given a service description with an orchestration:
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Reference Architecture Composite Services
At an internal level broker services are composed to form services such as:
Choreography-based execution
Orchestration-driven execution:
Given a service description with an orchestration:
• any contained goals are resolved using discovery, ranking and selection;• the choreographies of all component services are folded into the orchestration to form a single process;• this process is executed.
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Reference Architecture Composite Services
At an internal level broker services are composed to form services such as:
Choreography-based execution
Orchestration-driven execution
Goal-driven execution:
Given a goal description:• if it can be resolved to a service using discovery, ranking and selection then this service is executed according to choreography-based execution or orchestration-driven execution• if it cannot composition may be applied and the resulting composite service executed according to orchestration-driven execution.