Socio Technical

8/19/2019 Socio Technical

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SOCIO-TECHNICALSYSTEMS

Software Engineering (RPL)


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OBJECTIVES

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St!ent n!er"tan! w#at i" So$io-te$#ni$a% S&"te' an!ieren$e" wit# Te$#ni$a% Co'ter-*a"e! S&"te'

• St!ent n!er"tan! a*ot t#e $on$et of E'ergent "&roertie" "$# a" Re%ia*i%it&+ Perfor'an$e+ Safet& an!

• St!ent a*%e to e,%ain a$tiitie" of Software Engineerro$e""e"

• St!ent a*%e to e,%ain w#& organi.ationa% $onte,t of ae$t" it" !e"ign an! "e

• St!ent n!er"tan! a*ot /Lega$& S&"te'0 an! w#& "are $riti$a% to t#e oeration of 'an& *"ine""e"


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CATE1ORY O2 SYSTEM 3ITHSO2T3ARE•

Te$#ni$a% Co'ter Ba"e! S&"te'S&"te' w#i$# in$%!e #ar!ware an! "oftware *t not ro$ean! ro$e""e"4 2or e4g45 TV+ Mo*i%e 6 PC

• So$io-te$#ni$a% S&"te'S&"te' in$%!e" one or 'ore te$#ni$a% "&"te'" *t $r$ia%in$%!e 7now%e!ge of #ow "&"te' "#o%! *e "e! to a$#ie*roa!er o*8e$tie4 S&"te'" #ae !e9ne! oerationa% ro$ein$%!e eo%e a" in#erent art of t#e "&"te'+ goerne! *&r%e" w#i$# are ae$te! *& e,terna% $on"traint"


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A:TOMOBILE SOCIO-TECHNICALSYSTEMS


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ESSENTIAL CHARACTERISTICS O2 SOCIO- TECHNICAL SYSTEM

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It" e'ergent roertie" a" a whole not in!ii!a% a"&"te'. T#e e'ergent roertie" !een! on *ot# t"&"te' $o'onent" an! t#e re%ation"#i *etween t$an on%& *e ea%ate! on$e t#e "&"te' #a" *een a"

• T#e& are often non-!eter'ini"ti$4 2or a "e$i9$ in'a& not a%wa&" ro!$e t#e "a'e ott+ !een!in

#ow t#e "&"te' i" *eing "e!• It" "ef%ne"" of t#e "&"te' !oe" not on%& !een! o

"&"te' it"e%f *t a%"o t#e "ta*i%it& of t#e "itation w"&"te' i" *eing "e! "$# a" t#e re%ation"#i an! $*etween organi.ationa% o*8e$tie"


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EMER1ENT SYSTEM PROPERTIES

•

E'ergent Proertie" (C#e$7%an!+


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E@AMPLES O2 EMER1ENTPROPERTIESPROPERTY DESCRIPTION

Vo%'e T#e o%'e" or $aa$itie" of a "&"te' arie" !een!ing$o'onent" are arrange! an! $onne$te!

Re%ia*i%it& een! on $o'onent re%ia*i%it& *t ne,e$te! intera$$a"e new t&e" of fai%re w#i$# ae$t t#e re%ia*i%it& of t

Se$rit& A $o'%e, roert& t#at $annot *e ea"i%& 'ea"re!4 Attaneer *e anti$iate! *& t#e "&"te' !e"igner" w#i$# !efein "afegar!

Reaira*i%it& It re%ate! to #ow ea"& it i" to reair t#e "&"te'+ #ow ea"a$$e"" t#e fa%t& $o'onent"+ 'o!if& an! re%a$e t#e'

:"a*i%it& How ea"& it i" to "e t#e "&"te' w#i$# !efen! on t#e te$"&"te' $o'onent"+ it" oerator" an! oerating eniron


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OVERALL SYSTEM RELIABILITY

•

T#ree re%ate! in;en$e" on oera%% "&"te' re%ia*


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SYSTEM EN1INEERIN1

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S&"te' engineering i" t#e a$tiit& of specifyingdesigning+ implementing+ validating+ deployan! maintaining "o$io-te$#ni$a% "&"te'"

S&"te' engineer" are not 8"t $on"ent wit# "oftw

a%"o #ar!ware+ it" oerator an! eniron'ent4 A "oengineer" nee! n!er"tan!ing of "&"te' enginee*e$a"e ro*%e' of "oftware engineering often a "&"te' engineering !e$i"ion" (T#a&er+


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SYSTEM EN1INEERIN1

ATC F Airort TraG$ ContrS&"te' Engineering Pro$e""e"


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DIFFERENCES OF SYSTEM VS SOFTWARE

ENGINEERING PROCESSES


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SYSTEM RE:IREMENT E2INIT

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T#i" a$tiit& "e$i9e" w#at "&"te' "#o%! !o an! w#at it" e"an! !e"ira*%e "&"te' roertie" "#o%! *e t#ere4 Si'i%ar to "reire'ent ana%&"i"+ $reating "&"te' reire'ent !e9nitionino%e" $on"%tation wit# "&"te' $"to'er" an! en!-"er"4

• It "a%%& $on$entrate" on t#e fo%%owing t#ree t&e" of reir


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1OO VS BA SYSTEM RE:IREMENE@AMPLE

Proi!e a 9re an! intr!er a%ar' "&"te' for *i%!t#at wi%% roi!e interna% an! e,terna% warning of 9nat#ori.e! intr"ionK

To en"re t#at t#e nor'a% fn$tioning of t#e wor$arrie! ot in t#e *i%!ing i" not "erio"%& !i"rteeent" "$# a" 9re an! nat#ori.e! intr"ionK *roa!en an! %i'it t#e !e"ign $#oi$e" at t#e "a'e3it# t#i" o*8e$tie+ it a%%ow" intr!er rote$tion w%o$7ing te$#no%og& wit#ot a%ar' *t it 'a& a%"o

t#e "e of "rin7%er" for 9re rote$tion a" it ae$t


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SYSTEM ESI1N

T#e "&"te' !e"ign ro$e""

SPIRAL 'o!e% of reire'ent


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SYSTEM ESI1N PROCESSES


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SYSTEM MOELLIN1

ring t#e "&"te' reire'ent" an! !e"ign a$ti"&"te' 'a& *e 'o!e%%e! a" a "et of $o'onentre%ation"#i w#i$# i" $a%%e! "&"te' ar$#ite$tre wgra#i$a% i%%"tration w#i$# gie rea!er an oet#e "&"te' organi.ation4

At t#i" %ee% !etai%"+ t#e "&"te' i" !e$o'o"e! inintera$ting "*-"&"te'"4 An! in t#i" "tage aroriate to $%a""if& "*-"&"te'" a$$or!ing fn$tion4


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A SYSTEM ARCHITECT:RE E@AM

A "i'%e *rg%ar a%ar' "&"te' an! it" $orre"on!ing "&"te' !e"$ri


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EXAMPLE OF MODELLING SYSTEM

ARCHITECTURE IN DETAIL

B%oia*e 'oof "


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S:B-SYSTEM EVELOPMENT

• ring t#e !ee%o'ent of a%% "*-"&"te'"+ anot#er "&"te' ero$e"" 'a& *e nee!e! an! "tarte! for a arti$%ar in!i"&"te'4

• O$$a"iona%%&+ a%% are *i%t fro' "$rat$# an! "o'e "*-"&"te'$o''er$ia%+ o-t#e-"#e%f (COTS) "&"te' to *e integrate!"&"te'4

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S*-"&"te'" are "a%%& !ee%oe! in ara%%e%• 3#en *i%!ing "&"te' ino%e e,ten"ie #ar!ware e

'o!i9$ation after it0" 'anfa$tre! "a%%& e,en"ie+ "o ofaron!"0 to $o'en"ate for t#e ro*%e' i" nee!e!4 A" "$#+ !"oftware nee! to $on"i!er ;e,i*i%it& "o new reire'ena$$o''o!ate! wit#ot e,$e""ie a!!itiona% $o"t"4


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SYSTEMS INTE1RATION

After t#e in!een!ent%& "*-"&"te'" #ae 9ni"#e! t#e !ee%$an *e integrate! "ing a /*ig *ang0 aroa$# w#ere t#e&0re at on$e at t#e "a'e ti'e4 Howeer for te$#ni$a% an! 'ro"e"+ an in$re'enta% integration ro$e"" of "*-"&"te'" aroa$# for two rea"on"5


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SYSTEM EVOL:TION

• Large an! $o'%e, "&"te'" are nor'a%%& #ae a er& %ong %ifering t#e %ifeti'e+ $#ange" to $orre$t error or i'%e'entingreire'ent are er& %i7e%& to #aene!4

• S&"te' eo%tion i" $o"t%& for "eera% rea"on"5


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SYSTEM ECOMMISSIONIN1

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e$o''i""ion i" w#ere t#e "&"te' i" ot of "erHar!ware 'ig#t nee! to *e t#rown awa& *t wit$#ara$teri"ti$ of "oftware w#i$# !oe" not wear o$o'onent" $o%! *e ta7en an! re-"e! in ot#er"&"te'"4


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SOCIO-TECHNICAL SYSTEM ES

• :on !e"igning a "o$io-te$#ni$a% "&"te'+ we nee! to n#ow t#e "&"te' i" going to *e "e! an! we nee! to n!it" organi.ationa% eniron'ent4 If we !on0t+ t#e "&"te' ''eet t#e *"ine"" nee!"+ an! t#erefore it 'a& get re8e$

• H'an an! organi.ationa% fa$tor" to $on"i!er5


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LE1ACY SYSTEM

•

Lega$& "&"te'" are "o$io-te$#ni$a% $o'ter-*a"&"te' t#at #ae *een !ee%oe! in t#e a"t+ of"ing o%!er or o*"o%ete te$#no%og&4 T#e"e "&"te'on%& "ing #ar!ware an! "oftware *t a%"o %ega$ro$e""e" an! ro$e!re"4

• Lega$& "&"te'" are often a *"ine""-$riti$a% "&"t T#e& are 'aintaine! *e$a"e it i" too ri"7& to ret#e'


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CRITICAL SYSTEM

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Criti$a% "&"te'" are te$#ni$a% or "o$io-te$#ni$a% "&"t#at eo%e or *"ine"" !een! on4 If t#i" "&"te' fa'a& in$rre! "erio" ro*%e' an! %o""e"4

• T#ree 'ain $riti$a% "&"te' t&e"5


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CRITICAL SYSTEM EMER1ENTPROPERTY• T#e 'o"t i'ortant e'ergent roert& of $riti$a% "&"

it" dependability 4

• T#e ter' dependability (Larie+


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CRITICAL SYSTEM MOST 2AIL:RECOMPONENTS

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S&"te' #ar!ware fai%re *e$a"e of 'i"ta7e" in 'anfa$tring error"+ or %i'ite! %ifeti'e rea$#e!

• S&"te' "oftware fai%re *e$a"e of 'i"ta7e" in"e$i9$ation+ !e"ign an! i'%e'entation

• H'an oerator" fai%re


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SYSTEM EPENABILITY

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T#ere are for rin$ia% !i'en"ion" to !een!a*"#own *e%ow5


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SYSTEM EPENABILITY


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OTHER CRITICAL SYSTEMPROPERTIES• Reaira*i%it&

How ea"& it0" to *e 9, w#en t#ere i" a error o$$rre!4 Bt ta7e note t#atn$o''on w#en !ee%oing "&"te' "ing t#ir!-art& *%a$7-*o, $o'on

• Maintaina*i%it&S&"te' t#at i" ea"& to a!at w#en t#ere i" new reire'ent $#ange" wiro*a*i%it& of intro!$ing new error"

• Sria*i%it&S&"te' w#i$# i" a*%e to $ontine !e%iering "eri$e w#i%"t n!er atta$7"

"trategie" to en#an$e "ria*i%it& w#i$# are Re"i"tan$e to Atta$7+ Atta$Re$ognition+ a'age Re$oer& after Atta$7 (E%%i"on+ et a%4


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AVAILABLITY AN RELIABILITY

• S&"te' aai%a*i%it& an! re%ia*i%it& are $%o"e%& re%ate! roert

*ot# $an *e e,re""e! a" n'eri$a% ro*a*i%itie"4 Bt we $aa""'e re%ia*%e "&"te' wi%% a%wa&" *e aai%a*%e an! i$e e

• E,a'%e in P#one e,$#ange "wit$# w#ere aai%a*i%it& i" 'ot#an re%ia*i%it&4 So+ w#i%e t#e "er e,e$t a !ia% tone to #aeaai%a*i%it& reire'ent+ t#e re-$onne$tion "#o%! a%"o *e ere$oer4 So+ aai%a*i%it& i" 'ore $on$ern !een!a*i%it& rei

rat#er t#an re%ia*i%it& in t#e"e t&e of "&"te'"4• S&"te' A w#i$# i" fai%e! on$e a &ear #a" a #ig#er re%ia*i%it&

to "&"te' B w#i$# i" fai%e! on$e a 'ont#4 Howeer+ a""'eA ta7e" t#ree !a&" to re$oer #a" a %ower aai%a*i%it& rate $oto "&"te' B on%& nee! 'inte" to re$oer4


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AVAILABLITY AN RELIABILITY

• Reliability i" t#e ro*a*i%it& of fai%re-free oer a"e$i9e! erio! of ti'e

• Availability i" t#e ro*a*i%it& of "&"te'+ at oint wi%% *e oerationa% an! a*%e to !e%ier ree"te!"eri$e"4


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APPROACHES TO IMPROVE SYSTEMRELIABILITY

• 2a%t aoi!an$eee%o'ent te$#nie" "e! to 'ini'i.e t#e o""i*i%it& of 'i"an!or tra 'i"ta7e" *efore t#e& re"%t in "&"te' fa%t"4 E,a'aoi!ing error-rone rogra''ing %angage $on"tr$t "$# a" nor "tati$ ana%&"i" to ai! rogra' ano'a%ie"e,$etion" (*e#afro' e,e$tation")4

• 2a%t !ete$tion an! re'oa%

T#e "e of eri9$ation an! a%i!ation te$#nie" to !ete$t an! fa%t" *efore t#e "&"te' i" "e!

• 2a%t to%eran$e Te$#nie" t#at en"re t#at fa%t" in a "&"te' !o not re"%t in "error" or fai%re"4 E,a'%e5 Power rote$tion (:PS)+ ata *a$7*a%an$er+ ei$e ato-%o$7ing+ :!ata*%e Anti Vir" "&"te'"+ et


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INPUT-OUTPUT MAPPING SOFTWARE SYSTE

(LITTLEWOOD, 1990)

• Oera%% re%ia*i%it& 'o"t%& !een!" on t#e n

$a"ing erroneo" ott"4

• Re'oing Q of 7nown error" %e! toon%& Q of re%ia*i%it& i'roe'ent(Mi%%" et a%4+ )

• Man& !efe$t" on ro!$t" were on%&%i7e%& to $a"e fai%re after #n!re!" ort#o"an!" of 'ont#" of ro!$t "age


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SA2ETY

• Safet&-$riti$a% "&"te'" are "&"te'" w#ere it i" et#at "&"te' oeration i" a%wa&" "afe4

• Safet&-$riti$a% "oftware fa%%" into tow $%a""e"5


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SA2ETY

• Rea"on" w#& "oftware "&"te'" t#at are re%ia*%e are not ne$e""ar&


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SEC:RITY

• Se$rit& i" t#e "&"te' attri*te t#at re;e$t" it" arote$t it"e%f fro' e,terna% atta$7"4

• T#ree t&e" of !a'age $a"e! *& e,terna% atta$


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SEC:RITY

• Aroa$#e" to a""re "e$rit& of t#e "&"te'5


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:ESTION


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E@ERCISE

• E,%ore an! "t!& an e,i"ting "o$io-te$#ni$a% "&"te' in &o

"rron!ing to i!entif& t#e fo%%owing attri*te"5

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