s/w architecture

8/18/2019 s/w architecture

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Slide 1

Introduction toSoftware Architecture

TV Prabhakar


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Antecedents of Software Architecture


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What is Software Architecture?

• 150+ definitions• What are they?

• Both a rocess and a roduct

http://architecture%20definitions.ppt/http://architecture%20definitions.ppt/


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Slide 10

What tye of re!uire"ents dri#earchitectura$ desi%n?

Answer& 'ua$ity attribute re!uire"ents are theri"ary dri#ers for architecture desi%n(

)o you a%ree?


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Slide 13

Architecture and *unctiona$ity

• Functionality is largely orthogonal to qualityattribute requirements.

• Functionality is the ability of a system to do thework it was intended to do.

• Systems are decomposed into elements toachieve a variety of purposes other thanfunction.– Architectura$ choices ro"ote certain !ua$ities as

we$$ as i"$e"ent the desired functiona$ity(


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Slide 14

ffects of Architectura$ )ecisionson 'ua$ity Attributes

The degree to which a system meets it’s quality attributerequirements is dependent on architectural decisions.

• change in structure improving one quality oftenaffects the other qualities.

• rchitecture is critical to the reali!ation of qualityattributes.

• These product qualities should be designed into the

• architecture.

• rchitecture can only permit" not guarantee" any qualityattribute.


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Slide 15

Architecture,centric de#e$o"ent?

• rchitecture#centric development involves– -reatin% the business case for the syste"– .nderstandin% the re!uire"ents

– -reatin% or se$ectin% the architecture

– )ocu"entin% and co""unicatin% the architecture– Ana$y/in% or e#a$uatin% the architecture

– I"$e"entin% the syste" based on the architecture

– nsurin% that the i"$e"entation confor"s to the

architecture– aintainin% the architecture

The architecture "ust be both rescriti#e anddescriti#e(


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Slide 22

Attribute,)ri#en )esi%n

• The ttribute#$riven $esign %$$& method"developed at the S'(" is an approach to defininga software architecture that bases the

decomposition process on the quality attributesthe software must fill.

• a recursive decomposition process where" ateach stage in the decomposition" tactics and

architectural patterns are chosen to satisfy aset of quality scenarios.


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Slide 24

A)) ethods Inuts and 2ututs

• (nputs– constraints

– functiona$ re!uire"ents

– !ua$ity attribute re!uire"ents

• )utputs– first se#era$ $e#e$s of "odu$e deco"osition

– #arious other #iews of the syste" as aroriate

– set of e$e"ents for functiona$ity and theinteractions a"on% the"


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Slide 25

Architecture )ocu"entation

• rchitecture documentation is important if andonly if communication of the architecture isimportant.– 3ow can an architecture be used if it cannot beunderstood?

– 3ow can it be understood if it cannot beco""unicated?

• $ocumenting the architecture is the crowning

step to creating it.• $ocumentation speaks for the architect" todayand *+ years from today.


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I Add d b


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Issues Addressed byan Architectural Design

• 4ross deco"osition of a syste" into interactin% co"onents

– typically hierarchical– using rich abstractions for component interaction%or system ,glue-&

– often using common design idiomsstyles

• "er%ent syste" roerties– performance" throughput" latencies

– reliability" security" fault tolerance" evolvability• ationa$e and assi%n"ent of function to co"onents

– relates requirements and implementations

• n#e$oe of a$$owed chan%e– ,load#bearing walls-" limits of scalability and adaptation

– design idioms and styles


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Slide 28

Schoo$s of Thou%ht

• 6 + 1 View

• 7ach"ann *ra"ework

• , 2)P

• I

• 24• T24A*

• Product 8ines


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6 + 1 #iew• Phi$is 9ruchten: ationa$ Software: Architectura$ B$uerints ,

The 6+1 View 0ode$ of Software Archtecture : I Software:1;;5

– /se case view

– 0ogical view

– 1rocess view

– (mplementation view– $eployment view


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6+1 #iew


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What do the #iews do?

• $o%ica$ #iew is the ob:

• process #iew catures the concurrency andsynchroni/ation asects of the desi%n:

• physical #iew which describes the "ain%=s> of the

software onto the hardware and ref$ects its distributedasect:

• development #iew describes the static or%ani/ation ofthe software in its de#e$o"ent en#iron"ent

• i$$ustrated by a few se$ected use cases: or scenarios


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Taono"y of Sty$es

• )ata *$ow– 2atch Sequential

– $ataflow 3etwork%pipes 4 filters&5 acyclic" fanout" pipeline" /ni6

– 7losed loop control• -a$$,and,return

– 8ain programsubroutines

– (nformation hiding%$T" )b9ect na:ve clientserver&


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Taono"y((

• Interactin% Processes– 0; processes" distributed ob9ects

– 'vent systems5 implicit invocation" pure events

• )ata,oriented reository– Transactional databases

5 True clientserver

5 2lackboard

5 8odern compiler


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Slide 34

Taono"y((

• )ata,sharin%– compound documents

–


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Architectura$ Sty$es

• An architectura$ sty$e consists of&– componentconnector types" topology

– constraints on the topology and behavior

– an informal description of the costs and benefits of

the style" e.g. ,use the pipe and filter style whenreuse is desired and performance is not a toppriority-


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Sty$es: Patterns and Idio"s

• P2SA: Busch"ann eta$

• 42*

http://posa.ppt/http://posa.ppt/


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eferences

• sei(c"u(edu

• I

• 24

• P2SA

• 42*

• WWISA

• www(cetus,$inks(or%

• Brede"eyer(co"
http://www.cetus-links.org/http://www.cetus-links.org/

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