from legacy to state-of-the-art; architectural refactoring · example of refactoring goals +...

From Legacy to State-of-the-art; Architectural Refactoringby Gerrit Muller University of South-Eastern Norway-NISE

e-mail: [email protected]

Abstract

The market of electronic appliances shows a fast increasing diversity. Manufac-turers must be able to combine existing functions and new applications in a shorttime frame. A large amount of accumulated SW code (legacy) has to be reusedin new ways.The architecture(s) must be adapted to these new ways of working. Revolu-tionary adaptations have proven to be extremely risky. Opportunistic extensionand integration decrease the quality of the code base, making it increasingly moredifficult to continue. Architectural refactoring is a feedback based method to evolvean architecture.

Distribution

This article or presentation is written as part of the Gaudí project. The Gaudí projectphilosophy is to improve by obtaining frequent feedback. Frequent feedback is pursued by anopen creation process. This document is published as intermediate or nearly mature versionto get feedback. Further distribution is allowed as long as the document remains completeand unchanged.

June 21, 2020status: finishedversion: 1.3

TV domain HW Computin

g HW

TV domain platform

TV computing

Infra- structure

TV applications

TV Hybrid TV Digital TV

"All-in-one" combi TV

Set Top Box domain HW

Set Top Box Platform

M H P

Set Top Box

functions 3 rd party stack(s)

Computing HW TV domain HW

Computin g HW

TV domain platform

TV computing

Infra- structure

TV applications

Digital Video Platform SW


M H P

Set Top Box



TV domain platform

TV computing

Infra- structure

TV applications



Digital TV UI


TV domain HW Computing HW


M H P

Set Top Box functions

TV domain platform

TV computing

Infra- structure


3 rd party stack(s)

TV applications

storage domain HW

Storage applications

Digital TV UI

Storage srvices

PDP DVR

DVD RW

Set top

elec. Digital Cable

Gate way

ADSL TV2

re- ceiver

portable media- screen

trans mitter

game console

Today’s Audio Video Consumer Products

DVD

VCR

Audio Mini

Audio

Audio Portable

CD man

TV

Walkman Hard Disk

From

: CO

PA

tuto

rial,

Rob

van

Om

mer

ing

From Legacy to State-of-the-art; Architectural Refactoring2 Gerrit Muller

version: 1.3June 21, 2020

ARproductsRvO

Trend: Convergence of separate worlds

Telecom

Consumer

Computer



LWAconvergence

Integration and Diversity

mp3

dvd

set top box

flat display

pen

speech

cable

modem

firewall

Ambient Intelligence

living room

car

car navigation

pda

surveillance

camera

camera

GSM phone

computerCommunicator

television

games

sailboat

audio

microset

headphone

garment

watch



LWAintegrationAndDiversity

Today’s Video Products

Conventional TV

Set Top Box

Video Recorder

DVD Player

Cable Modem

PC



ARcurrentProducts

Evolution of Video Products

TV VCR

DVD

Set top

TV VCR

DVD

PDP VCR

DVD

Set top

elec.

Digital Cable

Digital Cable

Analog Cable

PDP DVR

DVD RW

Set top

elec. Digital Cable

Gate way

ADSL TV2

Multiple inputs Multiple stores Multiple displays Multiple applications Multiple formfactors

1

2

3

4 re-

ceiver


trans mitter

game console



ARproductEvolution

Distribution Scenario’s

Network

Thin Clients

All-in-one Server

All-in-one Combi's

Thin Servers

Clients

Network

Network

B A C

Network

Server

Server

Server

Client

Client

Client

D "All-in-one"

Combi's "Thin Servers"

"All-in-one" Home server

"Modular"



ARproductScenarios

Product Packaging Options

TV2

PDP DVR

DVD RW

Set top

elec. Digital Cable

Gate way

ADSL TV2

4A re-

ceiver


trans mitter

game console

PDP DVR

DVD RW

Set top

elec. Digital Cable

Gate way

ADSL TV2

4B re-

ceiver


trans mitter

game console

PDP DVR

DVD RW

Set top

elec. Digital Cable

Gate way

ADSL

4D re-

ceiver


trans mitter

game console

PDP DVR

DVD RW

Set top

elec. Digital Cable

Gate way

ADSL TV2

4C re-

ceiver


trans mitter

game console

"All-in-one" Digital TV

"Thin Servers" "All-in-one" Home server

"Modular"

TV2


version: 1.3June 21, 2020ARpackaging

Moore’s law

1965 1979

2000 1990

1 kB

64 kB2 MB

Moore's law

Fro

m: C

OP

A tu

toria

l, R

ob

va

n O

mm

erin

g



LWAmooresLawRvO

Problem: increasing SW size, decreasing reliability?

1000

100

10

man

year

s p

er

prod

uct

1990 1995 2000 2005

1000

10000

typi

cal a

mou

nt o

f er

rors

per

pro

duct



ARproblem

The Holy Grail: Reuse

REUSE

time

$$

Prom

ise

Reality



ARtheHolyGrail

Simplistic Architecting: Digital TV



MHP

Set Top Box


Computing HW

TV domain HW Computing

HW

TV domain platform

TV computing

Infra- structure

TV applications




analog TV Set top box

Digital Video Platform





MHP

Set Top Box


TV domain platform

TV computing

Infra- structure

TV applications

Digital TV UI

Digital TV

Merge

glue



ARdigitalTelevisionSimplisticArchitecture

Available Code Assets

>100 Myr

>100 Myr

>200 Myr >100 Myr





MHP

Set Top Box


TV domain platform

TV computing

Infra- structure

TV applications

Digital TV UI

"Legacy" code > 500 Myr

glue



ARdigitalTelevisionCodeAssets

Merge problems

tuner tuner MPEG MPEG

Duplication

Architectural mismatch : wrappers, translators, conflicting controls

Poor performance; additional resource usage

additional code and complexity,

no added value

UI UI

non problem Problems Architecture Reuse



ARmergeProblems

Solution: Architectural Refactoring

Refactoring

within short term business goals

with limited but substantial refactoring goals

clear product clear value proposition

feedback on direction

limited investment based on long term architecture vision



ARsolution

Example of Refactoring Goals

+ Decrease Code Size

+ Decrease Resource Usage * power * memory * silicon area

+ Increase Performance * response time * throughput

Qua

lity

time

0%

10%

20%

Improvement investment as percentage of total budget

+ Increase quality * decrease fault density



ARrefactoringGoals

Architectural vs Code refactoring

optimize() ...

add(a) ...

remove() ...

move() ...

accelarate() ...

add(a) ...

remove() ...

optimize() ...

move() ...

accelarate() ... add(a)

... remove()

...

Code Refactoring

old

new

old

new

new

Architectural Refactoring Function, Structure, Rationale

Mechanisms, Technologies

return( error )

free, alloc

raise( exception )

garbage collection

old



ARcodeVersusArchitecturalRefactoring

Prerequisite 1

Frequent feedback



Feedback

3 months

25 months

Start

Target

stepsize:

elapsed time:



LWAfeedbackLarge

Feedback (2)

3 months

25 months

2 months

12 months

Start Start

Target Target

stepsize:

elapsed time



LWAfeedbackMedium

Feedback (3)

3 months

25 months

2 months

12 months

1 month

8 months

Start Start Start

Target Target Target

stepsize:

elapsed time

Small feedback cycles result in Faster Time to Market



LWAfeedbackSmall

Prerequisite 2

Awareness of dynamics



Myth: Platforms are Stable

Architecture

Platform

Dynamic Market

Fast changing Technology

How stable

is a platform

or an architecture?

Components



LWAplatformStability

Platform Evolution (Easyvision 1991-1996)

1991

1992

1994

1991

1994

Last changed in:

Growth

Change

3rd

generation components are mature, active maintenance needed.

Growth and change continues, some "old" components become obsolete

1992

1996



LWAplatformEvolution

Prerequisite 3

Long Term Vision



Example Long Term Vision

Computing Infrastructure

Domain Infrastructure

Services Applications

Config

urati

on

i.e. In

terna

tiona

lizati

on

perso

naliz

ation

i.e. tu

nes,

themes

Framework

Long Term Vision: Reference Architecture + Sample implementation of Framework and Components

Reference Architecture



ARlongTermVisionExample

Don’t do

PDP DVR

DVD RW

Set top elec. Digital

Cable

Gate way ADSL TV2

re- ceiver


trans mitter

game console

PDP

DVR

DVD RW

Set top

elec.

Gate way

re- ceiver

trans mitter

Digital TV

Opportunistic Legacy

Integration

Proclaimed reuse

Set Top Box domain HW TV domain HW Computing HW



MHP

Set Top Box

functions

3 rd

party stack(s)

TV domain platform

TV computing

Infra- structure

TV applications

Digital TV UI

glue



ARtheWrongWay

Conclusion: Refactoring the Architecture is a must

TV domain HW Computin

g HW

TV domain platform

TV computing

Infra- structure

TV applications

TV Hybrid TV Digital TV

"All-in-one" combi TV



M H P

Set Top Box



Computin g HW

TV domain platform

TV computing

Infra- structure

TV applications



M H P

Set Top Box



TV domain platform

TV computing

Infra- structure

TV applications



Digital TV UI




M H P

Set Top Box functions

TV domain platform

TV computing

Infra- structure


3 rd party stack(s)

TV applications

storage domain HW

Storage applications

Digital TV UI

Storage srvices

PDP DVR

DVD RW

Set top

elec. Digital Cable

Gate way

ADSL TV2

re- ceiver


trans mitter

game console


version: 1.3June 21, 2020ARrefactoring

from legacy to state-of-the-art; architectural refactoring · example of refactoring goals +...

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