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Review

V&V

actions tobe carried

out

(entry criteria) (exit criteria)

inputs

ProjectControl info

info for

management

outputs

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systemengineering

AnalysisProject planning

design

code

testing &integration

Installation &

maintenance

-software part of some larger system-establish requirements for all elements of the system; assign some

to software

-understand information domain, functions, performance

and interfacing. Project plans made

-translate requirements into s/w architecture, data structures

and procedural details. A detailed design step can be added

-programming

-test logic and function interfaces

-deployment; make changes for

-Errors, performance-changes in requirement

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Problemdefinition

Feasibilitystudy

Analysis Systemdesign

Detaileddesign

Implemen-tation

Mainten-ance

Total accumulated cost

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Requirementsgathering

Quick

design buildprototype

evaluate &refine

Engineerproduct

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Evolutionary Development model [SE-7, Fig 4.2]

ValidationFinal

version

DevelopmentIntermediate

versions

Specification Initialversion

Outline

description

Concurrent

activities

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Evolutionary Development..

Main characteristics:

The phases of the software construction are interleaved

Feedback from the user is used throughout the entire process

The software product is refined through many versions

Types of evolutionary development:

Exploratory development

Throw-away prototyping

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Evolutionary Development

Advantages:

Deals constantly with changes

Provides quickly an initial version of the system

Involves all development teams

Disadvantages:

Quick fixes may be involved

Invisible process, not well-supported by documentation

The systems structure can be corrupted by continuous change

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Evolutionary Development

Disadvantages [contd]:

Special tools and techniques may be necessary

The client may have the impression the first version is very close to the final

product and thus be less patient

Applicability:

When requirements are not well understood

When the client and the developer agree on a rapid prototype that will be

thrown away

Good for small and medium-sized software systems

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Component-based Software Engineering

Requirementsspecification Componentanalysis

Developmentand integration

System designwith reuse

Requirementsmodification

Systemvalidation

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Component-based Software Engineering..

Main characteristics:

Makes intensive use of existing reusable components

The focus is on integrating the components rather than on creatingthem from the scratch

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Component-based Software Engineering.

Advantages:

Reduces considerably the software to be developed in-house

Allows faster delivery

In principle, more reliable systems, due to using previously tested

components

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Component-based Software Engineering

Disadvantages:

Compromises in requirements are needed

Less control over the systems evolution

Applicability:

When there is a pool of existing components that could satisfy the

requirements of the new product

Emerging trend: integration of web services from a range of suppliers

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1. Determine objectives,Alternatives, constraints

2. Evaluate alternatives,identify and handle risks

4. Plan next step 3. Develop the software

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Spiral Model

Main characteristics:

Also a hybrid model that support process iteration

The process is represented as a spiral, each loop in the spiral representing a process

phase Four sectors per loop: objective setting, risk assessment and reduction, development

and validation, planning

Risk is explicitly taken into consideration

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Spiral Model

Advantages:

Risk reduction mechanisms are in place

Supports iteration and reflects real-world practices

Systematic approach

Disadvantages:

Requires expertise in risk evaluation and reduction

Complex, relatively difficult to follow strictly

Applicable only to large systems

Applicability:

Internal development of large systems

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The Rational Unified Process

Phase iteration

Incept ion Elaborat ion Const ruct ion Transit ion

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Classification of CASE technology [SE-7, Fig 4.14]

Single-methodworkbenches

General-purposeworkbenches

Multi-methodworkbenches

Language-specificworkbenches

Programming Test ingAnalysis anddesign

Integratedenvironments

Process-centredenvironments

Filecomparators

CompilersEditors

EnvironmentsWorkbenchesTools

CASEtechnology

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