A Survey of Software Architecture

Viewpoint Models

Nicholas May

nick_may@netlink.com.au

Tuesday, 29th March 2005 A Survey of Software Architecture Viewpoint Models Slide 2

Surveyed five similar approaches to documenting software architecture

To identify:

•Their strengths and weaknesses

•An optimum approach to documenting software architecture

Overview

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Background:

• Software architecture

• Documentation approaches Survey:

• Comparison Framework

• Review of the five approaches Conclusions Questions

Contents

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What is Software Architecture?

Structures = Components and Connectors

Styles = Constraints on Composition.

Rationale = Non-Functional Requirements

Background

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Adapted from “IEEE Recommended Practice for Architectural Description of Software Intensive Systems”. IEEE (2000)

Background - IEEE Standard 1471-2000

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Viewpoint models utilize perspectives to separate the concerns.

Perspectives are variously called views, viewtypes, and viewpoints.

Different viewpoint models focus on the different uses of documentation.

• Communication.

• Design.

• Re-use.

Other frameworks exist for classifying documentation.

Background - Viewpoint Models

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Framework• based on IEEE 1471-2000, IEEE (2000).

Viewpoint Models:• “4+1” View Model, Kruchten, P. (1997).

• SEI View Model, Clements, P. et al. (2002b).

• ISO RM-ODP, ISO (1994).

• Siemens Four View Model, Soni, D. et al. (1995).

• Rational ADS, Norris, D. (2004).

Survey

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Stakeholderseg. Architects, Testers, Managers.from “Documenting Software Architectures: views and beyond” (Clements et al, 2002a, page 10).

Concernseg. Performance, Implementation, Privacy. from “Software Engineering” (Sommerville, 2000, page 101).

Structureseg. Decomposition, Layer, Process from “Software Architecture in Practice” (Bass et al., 2003, page 39).

Survey - Comparison Framework

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StakeholdersImplementers: Programmers and

Systems Engineers.

ConcernsReliability: Quality of Service, Fault Tolerance,

Availability, and Failure Modes.

StructuresDeployment: Hardware and Software

components.

Survey – Example Translations

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Survey – Summary of Models

Focus Features Viewpoints

SEI Communication Independent viewpoints 3 viewpoints

“4+1” Design Iterative design process 5 views

Siemens DesignFlow of information through viewpoints

4 views

RM-ODP Re-useDefines a common vocabulary

5 viewpoints

Rational ADS DesignDefined mappings between views

4 viewpoints

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0

2

4

6

8

10

12 "4+1"

SEI

RM-ODP

Siemens

RationalADS

Total

Stakeholders

Structures Concerns

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Conclusions - Viewpoint Groups

“4+1”model

SEImodel

Siemensmodel

RationalADS

FunctionalLogical

viewModule

viewtypeModule

view-

BehaviouralProcess

viewC&C

viewtypeExecution

view-

ExternalDevelopment

viewAllocationviewtype

Codeview

Realizationviewpoint

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Rational ADS - Requirements viewpointSEI - Module viewtypeSEI - C&C viewtypeSEI - Allocation viewtype

Conclusions - Optimum Set

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Map Stakeholders to Concerns

Determine Implicit Stakeholders

Verify Optimum Viewpoint Set using Case Studies

Conclusions - Future Work

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Software Architecture can be documented using different approaches

Viewpoint models use multiple perspectives based on the separation of concerns

Surveyed five viewpoint models

Identified their relative strengths and weaknesses

Identified an optimum set of viewpoints

Finale - summary

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Thankyou

Questions

Finale

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Adapted from “Architectural Blueprints – the 4+1 view model of software architecture”, Kruchten, P. (1997)

Survey - “4+1” View Model

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Module Viewtype

Component & Connector Viewtype

Allocation Viewtype

Survey - SEI View Model

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Enterprise View

Information View

Computational View

Engineering View

Technology View

Survey - RM-ODP

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Adapted from “Applied Software Architecture”, Hofmeister, C. et al. (2000).

Survey - Siemens Four View Model

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Adapted from “Communicating Complex Architectures with UML and the Rational ADS”, Norris, D. (2004).

Survey - Rational ADS

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Conclusions – Number of viewpoints addressing Structures

0 5 10 15 20

Number of Viewpoints

Decomposition

Uses

Layered

Abstraction

Process

Concurrency

Shared Data

Client-Server

Deployment

Implementation

Work Assignment

"4+1" SEI RM-ODP Siemens Rational ADS

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Conclusions – Number of viewpoints addressing Concerns

0 5 10 15 20

Number of Viewpoints

Usability

Performance

Space

Reliability

Portability

Delivery

Implementation

Standards

Interoperability

Ethical

Privacy

Safety

"4+1" SEI RM-ODP Siemens Rational ADS

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Conclusions – Number of viewpointsaddressing Stakeholder Roles

0 5 10 15 20

Number of Viewpoints

Architects /Requirements Engineers

Sub- System Architects /Designers

Implementers

Testers /Integrators

Maintainers

External System Architects /Designers

Managers

Product Line Managers

Quality Assurance Team

End User

Standard Writers

"4+1" SEI RM-ODP Siemens Rational ADS

Tuesday, 29th March 2005 A Survey of Software Architecture Viewpoint Models Slide 25

Bass, L. et al. (2003). Software Architecture in Practice. Addison Wesley, Boston, MA, USA, 2nd edition. ISBN 0-321-15495-9.

Clements, P. et al. (2002a)

Documenting Software Architecture: Views and Beyond. Addison Wesley, Boston, MA, USA, 1st edition. ISBN 0-201-70372-6.

Clements, P. et al. (2002b)

A practical method for documenting software architectures. http://www-2.cs.cmu.edu/afs/cs/project/able/ftp/icse03-dsa/submitted.pdf viewed on 20th September, 2004. Draft.

Hofmeister, C. et al. (2000).

Applied Software Architecture. Object Technology Series. Addison Wesley, Boston, MA, USA, 1st edition. ISBN 0-201-32571-3.

IEEE (2000) IEEE Recommended Practice for Architectural Description of Software-Intensive Systems. Institute of Electrical and Electronics Engineers. IEEE Std 1471-2000.

References

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ISO (1994) Reference Model of Open Distributed Processing (RM-ODP). International Organization for Standardization. Technical Report 10746.

Kruchten, P. (1997) Architectural Blueprints - The “4+1” View Model of Software Architecture. IEEE Software, 12(6):42–50.

Norris, P(2004)

Communicating Complex Architectures with UML and the Rational ADS. In Proceedings of the IBM Rational Software Development User Conference, 2004. Copyright 2004 IBM Australia.

Sommerville, I. (2000)

Software Engineering. Addison Wesley, Boston, MA, USA, 6th edition. ISBN 0-201-39815-X.

Soni, D. et al. (1995) Software architecture in industrial applications. In International Conference on Software Engineering, pages 196–207.

References - Continued