kmi.open.ac.uk semantic execution environments service engineering and execution barry norton and...

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

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Plan for the Day








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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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• Their Capabilities describe their functional abilities…

Capability

Interface


Postcondition

Effect

Choreography

Orchestration

State Signature

Transition Rules

Web Service

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• Preconditions express guarantees they expect from clients, purely over information they communicate…

Capability

Interface


Postcondition

Effect

Choreography

Orchestration

State Signature

Transition Rules

Web Service

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• Assumptions express general guarantees they expect of clients, involving the environment outside communications…

Capability

Interface


Postcondition

Effect

Choreography

Orchestration

State Signature

Transition Rules

Web Service

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• Postconditions express guarantees they make over information communicated back, providing the preconditions and assumptions are met by the client…

Capability

Interface


Postcondition

Effect

Choreography

Orchestration

State Signature

Transition Rules

Web Service

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• Effects express the general guarantees made, outside information directly communicated, providing the preconditions and assumptions are met by the client

Capability

Interface


Postcondition

Effect

Choreography

Orchestration

State Signature

Transition Rules

Web Service

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• 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


Postcondition

Effect

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• The choreography expresses communications the service engages in with its clients…

Capability


Orchestration

State Signature

Transition Rules

Web Service


Postcondition

Effect

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• The state signature describes these communications semantically, by linking modes to ontological concepts

Capability


Orchestration

State Signature

Transition Rules

Web Service


Postcondition

Effect

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• The state signature describes these communications semantically, by linking modes to ontological concepts:

– IN modes describe communications the service is able to receive

Capability


Orchestration

State Signature

Transition Rules

Web Service


Postcondition

Effect

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– IN modes describe communications the client would like to receive;– OUT modes describe communications the service is able to send

Capability


Orchestration

State Signature

Transition Rules

Web Service


Postcondition

Effect

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– 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


Orchestration

State Signature

Transition Rules

Web Service


Postcondition

Effect

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• Transition rules link communications into a stateful interaction

Capability


Orchestration

State Signature

Transition Rules

Web Service


Postcondition

Effect

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• Transition rules link communications into a stateful interaction:– Transition rules may be used in matching and (process) mediation against goals,

Capability


Orchestration

State Signature

Transition Rules

Web Service


Postcondition

Effect

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• 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


Orchestration

State Signature

Transition Rules

Web Service


Postcondition

Effect

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• 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


Orchestration

State Signature

Transition Rules

Web Service


Postcondition

Effect

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Goal Description

• Goals describe requirements from client perspective…

Goal

Capability

Interface


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


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


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


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


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


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


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


Orchestration

State Signature

Transition Rules

State Signature

Transition Rules


Postcondition

Effect

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Goal Description

• The choreography expresses communications the client is able to engage in…

Goal


Orchestration

State Signature

Transition Rules

State Signature

Transition Rules

Capability


Postcondition

Effect

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Goal Description

Goal


Orchestration

State Signature

Transition Rules

State Signature

Transition Rules

• The state signature describes these communications semantically, by linking modes to ontological concepts

Capability


Postcondition

Effect

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Goal Description


– IN modes describe communications the client would like to receive

Goal


Orchestration

State Signature

Transition Rules

State Signature

Transition Rules

Capability


Postcondition

Effect

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Goal Description


– IN modes describe communications the client would like to receive;– OUT modes describe communications the client is able to send.

Goal


Orchestration

State Signature

Transition Rules

State Signature

Transition Rules

Capability


Postcondition

Effect

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Goal Description

Goal


Orchestration

State Signature

Transition Rules

State Signature

Transition Rules

• Transition rules link communications into a stateful interaction

Capability


Postcondition

Effect

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Goal Description

Goal


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


Postcondition

Effect

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Goal Description

Goal


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


Postcondition

Effect

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• 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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• WG-Mediators describe which goals are met by a web service;• the descriptions may have some mismatch to be mediated

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OO-Mediator

Mediation Goal

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• 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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OO-Mediator

Mediation Goal

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– an oo-mediator may be supported by mapping rules between dissimilar ontologies;– a mediation service identifies a web service capable of resolving the mismatch

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OO-Mediator

Mediation Goal

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– 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)

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OO-Mediator

Mediation Goal

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Plan for the Day








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WSMO, WSML and WSMX

Conceptual Model for SWS

Ontology & Rule Language for the Semantic Web with built-in

support for WSMO

Semantic Execution Environment

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WSMO, WSML and SEE


Ontology & Rule Languages Semantic Execution Environments

OWL, OCML, SWRL etc.

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WSMO, WSML and SEE


Ontology & Rule Languages Semantic Execution Environments and

independent broker services

OWL, OCML, SWRL etc.

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Glue 2

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Semantic Execution (Developing) Standards


Ontology & Rule Language for the Semantic Web with built-in

support for WSMO

Semantic SOAReference Ontology

SEEReference Architecture

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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

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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

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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

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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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• Base services, providing storage and reasoning support, underlie all broker services

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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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• Broker services are otherwise independent and atomic behaviours expected of a SEE

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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







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Quality of Service Aspects

• 16 ontologies have been recommended for modeling WSMO

Non-functional aspects of Web services

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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 ServiceDescription

Instance Data

Instance Data

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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




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

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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


DescriptionWeb ServiceDescriptionOntology InstancesOntology Instances


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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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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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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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.

kmi.open.ac.uk semantic execution environments service engineering and execution barry norton and...

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