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Software Reusability

Main issues:

Why is reuse so difficult

How to realize reuse

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Reuse dimensions

Things being reused: components, concepts,

Scope: horizontal vs vertical

Approach: systematic or opportunistic

Technique: compositional or generative

Use: black-box or white-box

Product being reused: source code, design,

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Success criteria for component libraries

Well-developed field, standard terminology

Small interfaces

Standardized data formats

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Requirements forcomponent libraries

Searching for components

Understanding/evaluating components found

Adapt components if necessary

Compose systems from components

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Component evaluation, useful information

Quality information

Administrative information (name developer,modification history, etc)

Documentation

Interface information

Test information

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Reuse process models

Software development with reusePassive

Component library evolves haphazardly

Software development for reuse

Active

Reusable assets are developed, rather than found by accident

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Software development with reuse

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Software development for reuse

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Software development for reuse

Often two separate development processes:

Development of components (involving domain analysis)

Development of applications, using the available components

Specific forms hereof:Component-based software development

Software factory

Software product lines

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Reuse tools and techniques

Languages to describe compositions

Module Interconnection Language (MIL)

Architecture Description Language (ADL)

Middleware (CORBA, JavaBeans, .NET)

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Characteristics of successful reuseprograms

Extensive management support

Organizational support structure

Incremental implementation

Significant success

High incentives

Domain analysis done

Attention to architectural issues

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Non-technical aspects of software reuse

Economics: it is a long term investment

Management: it does not happen spontaneously

Psychology: people do not want to reuse someoneelses code

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Reuse devils loop

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Summary

We can reuse different things: code, design,

Reuse can be systematic (software developmentfor reuse), or opportunistic (software development

with reuse)

Reuse does not just happen; it needs to be planned

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