Service-Oriented Software Engineering Lecture

7/27/2019 Service-Oriented Software Engineering Lecture

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Service-Oriented

Software Engineering

An Introductory Lecture

Toni Ruokolainen

2006


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Contents

n Introduction

n Challenges & motivation

n Service-Oriented Computing paradigm

n Characteristics of Service-Oriented SoftwareEngineering

n Model-Driven Engineering

n Current state, trends, challenges


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Introduction Business networking

perspective

Introduction - Electronic Business Networking

eCommerceTarget areas:

- Consumer sales

Technologies:

- Web Shops- portals

eBusinessTarget areas:

- sales

- procurement

- distribution

Technologies:

- XML

- EAI platforms

- Web Services

- Software Components

eCollaborationTarget areas:

- networked processes

- network wide forecasting

- collaborative planning

- network wide product & production

design

Technologies:

- eBusiness standards

- Integration platforms

- Semantic Web

- SOA

Time

Development

level

Jyrki Haajanen, VTT


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Introduction - Development of

distributed computing technology

n Centralized Client-server Peer-to-peerCollaborative

n From technological integration to federation

n From tightly coupled to loosely coupled

n

From centralised to distributed controln Collaborative systems

n Autonomous participants, heterogenenous resources,dynamic environments

n B2B, P2P, MAS,

n Maturation of communication technology

n Can now consider semantic & pragmaticinteroperability


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Vision: Collaborative computing

customer

selllerwarehouse

logisticsbank

order

invoice receipt

delivery order

order

docket

VISA

LorryService IncPressH

ouse X

EnsoPaper IncPrimary storehouse

Partner discovery

interoperability

Collaboration contract

(business network model,partners,

Technical details, contractbreach recoverymechanisms)

Contract breachmanagement

Copyright 2006 by Lea Kutvonen


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Challenges

n Establishing interoperability in collaborative systems

n Autonomy, heterogeneity, dynamism

n Bridging the semantic gap between domain conceptsand technology

nManaging the complexity of computing platformsn Maintainability of software

n (Re)configuration

n Platform evolution

n Providing agility

n

Agile development methodologiesn On-the-fly collaboration establishment

n Flexibility of software systems


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Motivation for research

n Support for prevailing business modelsn Outsourcing, globalisation

n Emphasizes agility and low time-to-market

n Enhance modularity & reusability of systemsn Provide meaningful abstractions for SE

n Separation of concernsn

Functional & non-functional aspectsn Establish more robust & effective software development

n Model-driven engineering: productivity, agility, fail-safety

n Enhancing maintainability of EISn From monolithic systems to more flexible service-oriented systems

n Increase ROI

n Open service marketsn Fertilizes / enhances new kinds of business models?

n SMEs role and possibilitiesn Virtual enterprisesn Clustering


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Service-Oriented Software

Engineeringn Emerging software-engineering

discipline

n Considers services as theprimary elements of design andproduction

n Utilisation of Service-Oriented

Computing paradigm throughoutthe development process

n Emphasizes the role ofmeta-information

n Development throughservice discovery &composition

n SOSE = SOC paradigm + SEprocess / methodology + SOA-based tool-chain

Service-Oriented

Computing

Software

Engineering

process

SOA based

Tool-

chain

SOSE


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Service-Oriented Computing

n (SOC) is the computingparadigm that utilizes servicesas fundamental elements fordeveloping applications

n Conceptsn Service descriptionsn Service compositionn Service-Oriented Architecture

n Characteristicsn Loose couplingn Description-centricityn Autonomyn Collaborative computing

n Service life-cyclen Define, describe, find, bind

Copyright 2003 by M. Papazoglou &

D. Georgakopoulos


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Service Descriptions

n Two kinds of descriptions

n Service types

n Service offers

n Service type characterises common properties for a

kind of servicesn Defines syntax and semantics of a service interface

n Ontologies, common vocabularies

n Service offer advertises a service implementation

n Published by service provider

n Conforms to a service type


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Service Composition

n Based on service descriptions

n Results in a composite servicen Added value (e.g. Travel company)

n Composition synthesis

n Composition execution

n Prevalent types of service compositionn

Process-based composition (Enterprise computing, workflow systems)n Orchestration, choreography

n WS-BPEL, WS-CDL

n Ad-hoc composition (Roman model)n FSM-based automaton synthesis

n Logic-based composition (AI, Semantic Web)n Pre-/post-condititions, planning

n Architectural composition (ADL:s, CBSE)n Components & connectors


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Service-Oriented Architecture

n An architectural style


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Service-Oriented Software

Engineering process

n Traditional software engineering process

1. Analysis

2. Design

3. Validation and verification

4. Implementation5. Maintenance

n Is this applicable for SOSE?

n What methods / techniques are feasible in eachphase?

n What are the methods and techiques of a SOSE-process?

n Is a SOSE process different wrt. CBSE?


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Service-oriented analysis

n Identify the conceptual services and collaboration patterns

n Define service requirements

n Services are coarse-grained objects / components

n Technology driven: wrapping legacy systems behind uniformservice interfaces

n Bottom-up approachn Providing new servicesn Identifying existing services

n Service as a conceptn Ideology driven: bridging the gap between business and

technology

n Top-down approach

n Start from business values and modelsn Meet-in-the-middle

n Impact of legacy systems


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Service-oriented analysis

n Example activities

n Identifying roles

n Identifying interactions

n

Identifying service capabilitiesn Functionality

n NFA

n Identifying collaborations (or service-oriented

system architectures)

n Identifying pre-existing service types


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Service-oriented design

n Use domain specific vocabulary to define and describe conceptsgiven by preceeding analysis phase

n Example activities

n Creating / selecting ontologies

n Vocabulary to be used

n Modelling service interfacesn Modelling behaviour

n Service interface behaviour

n Business processes

n Modelling business roles

n Service interfaces

n Service compositionsn Discovery & Selection of services

n If pre-existing services are available


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Validation and verification of service-

oriented software systemsn Validation

n Testing service designs against design requirementsn Simulating

n Test generation

n Validating conformancen NFA

n Composite properties

n Verification of designsn Interoperability with prescribed collaborations and services

n Formal verification of properties

n Correctness of service compositions

n Most of the standard validation procedures only applicable at runtimen Need of service monitoring

n Need of contract-driven collaboration

n To which extent is validation of service-oriented systems possiblestatically?


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Implementing service-oriented systems

n Model-Driven Development

n Both SOC and MDE emphasize to role of

models as first-class entities

n

Needed: A SOC-programming languagen Native XML-based messaging primitives

nA few research prototypes exist

n Implementation technologies

n Web Servicesn Local deployment target (J2EE, BPEL,)


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Maintenance of service-oriented

software systems

n Deployment of services

n Configuration of services

n Establishment of collaborations

n Runtime managementn Monitoring

n Evolution support

n Platform / service evolution

n Evolution at different levels of abstraction


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PSMWS specific

platform models

PSMEJB specific

platform models

PSM.NET specific

platform models

Execution infrastructures

.NET/COMEJB/J2EEWS Others

PSMother specific

platform models

Model to code

Transformation

NFA ModelsDomain Models PIM PIM

Model Transformation

Architecture style

Platform Description

Model (PDM)

Architecture

model

Model Transformation

UML profiles for : CCM, EJB, .NET,

SOA

Copyright 2004 by Philippe Millot (slightly edited by TR)

Overview of Model-Driven Engineering


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Hierachy of models

n MDE considers models as primaryengineering artifacts

n Models are representations ofreality for a given purpose

n Models conform to a meta-model

n Provides a typing scheme for

model elementsn Formal specification of an

abstraction

n Metamodels are described withmetametamodels

n A language for definingmetamodels

n E.g. OMGs MOF (UML is basedon MOF)

Metamodel

Model

System

conformsTo

representedBy


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MDE principles

n Three principles of MDE

n Direct representation

n Automation

n Standards

MDE

Direct

representation

Standards Automation

Adapted from David Frankel: An MDA Manifesto

MDA Journal, May 2004

http://www.bptrends.com
http://www.bptrends.com/http://www.bptrends.com/


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MDE: Direct representation

n Direct representationn Direct coupling of problems to solutions

n Domain-Specific (Modeling) Languages (DSML, DSL)

n DSML defines for a particular domainn Primary concepts and vocabulary

n Relationships between conceptsn Precise semantics for concepts and relationships

n E.g. specific languages for avionics, online financialservices, inter-enterprise computing,

n Big players in DSML fieldn

UML (2.x) & UML Profiles (OMG)n Software Factories (Microsoft)


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UML as a DSML

n Lightweight extension with profiles

n Extends the elements of the UML meta-model

n Profile = Set of stereotypes & Tagged values

n Does not provide means for precisely defining

semantics associated with extensions!France, Ghosth, Dinh-Trong: MDD Using UML 2.0:

Premises and Pitfalls, Computer, February 2006, IEEE

n Heavyweight extension via MOF

n Extends the UML-meta-model itself

n All the modeling mechanisms and semantics of MOFare applicable


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MDE: Automation

n Automation

n Facets of DSLs areintended to be automaticallyprocessed

n Transformations

n Model-to-Model (M2M)

n Transformation languagesn QVT, ATL, YATL, MTL,

GReAT,

n Code generation

n Model-to-Text (M2T)

n E.g. PSM-to-Java, EDOC-to-EJB,

n QVT M2T RFP, MOFScript

CIM

PIM

PSM

M2M

M2M

PDM

Model

weaving

Text (code)

M2T

MODELS

PLATFORMS


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MDE: Standards

n Use of open standards to establish interoperability

n Model interoperability

n MOF, XMI

n Meta-model bridging through unified meta-metamodel

n Infrastructure interoperabilityn Middleware infra (CORBA, WS)

n Messaging (XML-standards, SOAP, GIOP/IIOP)

n Communication platforms (TCP/IP)


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MOF

Picture taken from http://de.wikipedia.org/wiki/Meta-Object_Facility
http://de.wikipedia.org/wiki/Meta-Object_Facilityhttp://de.wikipedia.org/wiki/Meta-Object_Facility


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Web Services

Copyright 2004 by Lawrence Wilkes


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MDE buzzwords

n MDD = Model-Driven Development

n Use of (prescribed) models and transformations duringsoftware development

n Also used commonly as a synonym for MDE

n MDA = Model-Driven Architecture

n OMG initiative

n UML + MOF + QVT + few other standards..

n Software factories

n Microsoft Domain-Specific Language Tools

n Software factory = model-driven product line

n Combines model-driven & component-basedtechniques with product-line principles


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SOC & Model-Driven Engineering

n SOC provides feasible abstractions

n SOC complements the MDA approach by providing a

template for structuring business systems and

integration solutions, the service paradigm(Piccinelli

and Skene, SOSE-book, 2005)

n Both emphasize the role of meta-information

n The MDA complements SOC by promoting the early

modeling of systems to understand their operation, a

necessary prerequisite when wrapping a system with a

service interface(Piccinelli and Skene, SOSE-book,

2005)


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Tools needed for SOSE

n Service-oriented analysis techniques

n Domain-specific modeling language (family)

n Supporting viewpoints and modeling aspects

n E.g. ODP viewpoints

n Validation & verification tools

n Preferably weaved to design and implementation toolstransparently

n A SOC programming language

n Native support (type system) at least for messaging andXML-handling

n A software-engineering tool-chain natively paired with SOCinfrastructure

n

Discovery of available service types / offersn Publication of new service types / offers

n Deployment & configuration of service implementations


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A SOA tool chain


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ModelBus

Copyright 2004 by Philippe Millot

MODELWARE (MODELing solution for softWARE systems)

EU Information Society Technology (IST) Project

http://www.modelware-ist.org
http://www.modelware-ist.org/http://www.modelware-ist.org/


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Trends in research

n Concepts of SOSE

n SOC concepts

n Service composition

n SOSE specific SE processes / phases

n Service & collaboration modelling languagesnApplication of formal methods

n Model-Driven Engineering

n Model-weaving, transformation semantics

n Technology for SOCn Web Services


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Research questions (1/4)

nAnalysis & design

n What are the concepts and methods to beused?

nAre component-based analysis and design

methods adequate?n What would a service-oriented analysis

method look like?

n What are the quality attributes for services?

n Low coupling & high cohesing; How should these

be interpreted in the context of service-orientedcomputing?


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n Validation & verification

n How can service-oriented designs be validated forconformance against the requirements?!

n What kind of testing methods are applicable?

n Simulation is quite natural choice..

n What kind of verification methods should be used?

n Role of verification during different phases of SOSEprocess?

n Verification methods before / during / afterimplementation Design verification

SOC programming language type systems

Dynamic model checking / conformance validation


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n Implementation

n What kind of facilities are needed?

n What kind of meta-information repositories?

n Support for different composition frameworks

n Implementation models (MDE)

n Programming languages for SOC

n Static / dynamic aspects of service developmentn SOC is inherently dynamic environment

n What can be done before / during maintenance phase?

n How to identify ths distinction during the engineering process?

n How to address dynamic aspects? Are they modeled explicitly? Left implicit and dealt in the platform level?

n MDE challenges

n Viewpoint modelling & correspondences / relationships between viewsn Aspect languages & model weaving (esp. NFA)

n Static & dynamic use of meta-information


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n Maintenance

n Deployment of service-oriented systems

n Deployment of complex systems is painfull Especially if configurations are to be changed often

n What kind of configuration mechanisms are needed?

n Establishment and maintenance of service-orientedcollaborations

n Facilities for establishing and upholding contracts

n Evolution management

n What kind of changes can be tolerated?

n How? At which points of time?n At which level? (implementation, model, meta-model)


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Conclusion

n SOSE is still an open fieldn Results stemming primarily from OOSE & CBSE

n There is no complete SOSE process available, yet?

n SOC has been quite techonology drivenn Strong role of industry in Web Services standardisation

n The role of SOC infrastructure in the software engineering process hasbeen left quite vague

n MDE is a good fit for SOSEn Both emphasize the role of meta-information

n Quite easy to generate (at least simple) skeleton code for service-interfaces

n In infancy: model (aspect) weaving, compositionality, separation ofconcerns (viewpoints)

n SOC & SOSE emphasize convergence between business &infrastructuren There is no strict phasing of a SOSE process but inter-dependecies

instead?


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Practicalities

n Contact: [email protected]

n Room: D219

n Timetable for the next few weeks

n 12.09.2006 No session

n 19.09.2006 Abstracts due!

n PDF-format, 1-2 pages (look at the seminar page formore information)

n 26.09.2006 No session

n 03.10.2006 First presentation

n Reservation of time-slots

n Now..

n Opponents(?)
mailto:[email protected]:[email protected]

Service-Oriented Software Engineering Lecture

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