Reuse

Basic concepts

Rationale for reuse

Save calendar time Save person hours Reduce process risk Increased quality Standards compliance

What is re-used?

Software: Application reuse Component reuse Object and function reuse Test cases Test data Document content

Experience: Design patterns Architectural styles Processes Documents Conventions and standards

Classification of reuse

Product Scope Vertical – within domain Horizontal – across domains

Mode Planned Opportunistic

Intention Black-box Clear-box

Technique Compositional Generative

Techniques

Program libraries COTS Design patterns Middle-ware integration frameworks Legacy system wrapping Service-oriented systems Software product lines Commonalities Variation points

Program generators Software/Experience Factory

CORBA

Source: http://www.cs.wustl.edu/~schmidt/

Object-oriented frameworks

Object Oriented Framework Developmentby Marcus Eduardo Markiewicz and Carlos J.P. Lucena

Simple framework - JUnit

Object Oriented Framework Developmentby Marcus Eduardo Markiewicz and Carlos J.P. Lucena

Web-services

Source: H. Voormann ,Wikipedia

Service-oriented architecture

Design: Florian Lindner

Meta-data describes functionaland non-functional properties.

planetary1=110/50

C4=0.12 C5=0.12

planetary2=110/50

C6=0

.12

bearing2

C8=0.12

demultiplex

shaftS=2e-3S

planetary3=120/44

C11=0.12

shaftS1=2e-3S

C12=

0.12

bearing1bearing4

Modelica Visual Programming:Decomposition and Abstraction of an Automatic Gearbox

inertialx

y

axis1

axis2

axis3

axis4

axis5

axis6r3Drive1

1r3Motor

r3ControlqdRef1

S

qRef1

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k2

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qddRef cut joint

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qd

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Jmotor=J

gear=i

spring=c

fric

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Srel

joint=0

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Vs

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emf

La=(250/(2*D*wm

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Rd2=100

C=0.004*D/w m

-

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Rd1=100

Ri=10

Rp1=200

Rp2=

50

Rd4=100

hall2

Rd3=

100

g1

g2

g3

hall1

g4

g5

rw

qd q

rate2

b(s)

a(s)

rate3

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rate1

b(s)

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tacho1

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Kd

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w Sum

-

sum

+1

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pSum

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0.3

tacho2

b(s)

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Srel = n*n' + (identity(3) - n*n')*cos(q) - skew(n)*sin(q);wrela = n*qd;zrela = n*qdd;Sb = Sa*Srel';r0b = r0a;vb = Srel*va;wb = Srel*(wa + wrela);ab = Srel*aa;zb = Srel*(za + zrela + cross(wa, wrela));fa = Srel'*fb;ta = Srel'*tb;

Hierarchical Composition of a Modelica Model of anIndustrial Robot

Experience factory

Cost of reuse

Development for reuse Long-term increased maintenance costs Lack of tool support Non-invented-here (NIH)-syndrome Creating and maintaining a repository Finding, understanding and adapting reusable components Conflict project and line management

Experience 14

Characteristic HP project 1 HP project 2

size(ncss)

1100 700

quality 51% fault reduction 24% fault reduction

productivity 57% increase 40% increase

time-to-market - 42% reduction

Experience 24

HP products Air traffic control system

Menu- and forms management system

Graphics firmware

Relative cost to create reusable code (%)

200 120-480 111

Relative cost to reuse (%)

10-20 10-63 19

Experience 34

NEC: Reuse templates and algorithms 3 times better quality metrics

Hitatchi Reuse templates generated – total code ratio: 60-98%

Fujitsu Experience factory + job rotation Projects completed at time: Before: 20% After: 70%

Experience 44

Display HTML-tables 500 LOC two versions highly reused

Discussion forum 3000 LOC iteratively developed hard to understand

Contact-based network 10000 LOC 3 earlier versions needs technical skills instantiation easy

Experience: Start with small components Frequent releases Rewrite complicated code Well-known areas Document with examples Careful maintenance of repository Requires a re-use company

culture

Source: Ericsson: LiTG-IDA-Ex-01/19

Bottom-line is reuse worth the investment?

time

money

investment

income rest value

NPV = Σ CFi/(1+k)i - I0

k reflects: Compensation for waiting Compensation for inflation Compensation for risk

cash flow per time unit