1. an introduction to systems analysis and modelling (1).pptx
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An Introduction toSystems Analysis
and Modelling
Dr Kristin Stock
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OutlineWhat, Why, When and Where?
Diferent levels o modelling (conceptual, low leveletc!
"odelling and Design # what is design, how does itrelate to what we will cover in this course?
$he systems development liecycleSystems development methodologies
Systems analyst roles and skills
%ro&ect management, especially re 'S) $ools
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What is Systems nalysisand "odelling?
*ow doprogrammersknow what to write
in their code?
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What is Systems nalysisand "odelling?Systems analysis and modelling is a process
o+identiying the prolem that needs to e
solved
analysing the current situation
identiying re-uirements or the new systemmodelling those re-uirements in a systematic
way
creating a clear speci.cation o what the
system must do
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What is Systems nalysisand "odelling?When we talk aout specifying what the
system must do, speci.cally this can include+What data is needed
$he rules that govern that data
$he rules or how that data will e processed
$he layout o user interaces, reports, etc/ules aout access constraints
)0pectations aout the perormance o thesystem
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1s it aout designing a
system?
Well2yes, utthere arediferentde.nitions o
design
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What is the diference etweenanalysis, modelling and design?
nalysis is prolem ocussed
Design is solution ocussed3ut one morphs into the other through the
process
$he tools we use or analysis are also used or
designWe model the e0isting process, and then we
model our design o the new process
We can sometimes use this to generate code2
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Why Systems nalysis and Design? $o ensure the system meets the
needs it is intended to meet
$here is a long history oe0pensive 1$ systems that ailed tomeet user needs
$o ensure system -uality
$o ensure a good .t with the 1$environment
4ltimately2 to provide value tothe organisation
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)0amples o %ro&ect 5ailures6ational *ealth Service, 4K http+77calleamcom7W$%57?p89::;
$ransit $icketing uthority, "elourne,ustraliahttp+77calleamcom7W$%57?p8>
http://calleam.com/WTPF/?p=2003http://calleam.com/WTPF/?p=455http://calleam.com/WTPF/?p=1881http://calleam.com/WTPF/?p=1881http://calleam.com/WTPF/?p=1881http://calleam.com/WTPF/?p=455http://calleam.com/WTPF/?p=455http://calleam.com/WTPF/?p=2003http://calleam.com/WTPF/?p=2003
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$he systemsanalyst+
translates,connects
communicates
ridges the gapetween the
users7organisation and the
technologicaldetails
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When?/ight at the eginning@
When the pro&ect idea
is .rst ormed, somesystems analysisactivities areappropriate
'an continuethroughout, dependingon SDA' methodology
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Where? $he systems analyst needs to spend
time with the users
6eed to oserve and understand thecurrent situation, systems andenvironment
$his is the oundation or a good
system speci.cation
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Diferent Aevels o
"odelling
'onceptual
Aogical
%hysical
1ncreasing levels o detail
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'onceptual nalysis and "odelling*igh level
Sketches out road concepts
'an work with users to de.ne high levelconcepts
eg 'oncept "apping
house street city
is inis in
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Aogical nalysis and
"odelling"uch more detailed
1ndependent o implementation
Does not depend on a particular operatingsystem, sotware or hardware
1mplementation decisions can e madeseparately, later
'hanges in the implementation do not afectthe logical design
%1" 8 platorm independent model
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%hysical nalysis and "odelling"oves rom logical design into design on a
particular operating system, hardware,sotware
)g 'reating the actual dataase tales,creating sotware classes etc
Some tools are availale to generate some
parts o the physical design rom the logicaldesign models
)g logical dataase design can e used togenerate speci.c Oracle, SBA Server
dataases
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Systems Development
Aie 'ycle (SDA'!
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$he SDA' %rocess
$he process consists o our phases
)ach phase consists o a series o steps)ach phase is documented
(deliverales!
%hases are e0ecuted se-uentially,incrementally, iteratively or in someother pattern
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Buestions to e
nswered%lanning phaseWhy should we uild this system?
What value does it provide?
*ow long will it take to uild?
nalysis phaseWho will use it?
What should the system do or us?Where C when will it e used?
Design phase*ow should we uild it?
1ncreasinglevels odetail
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SDA'+ $he %lanning
%hase> %ro&ect 1nitiationDevelop7receive a system
re-uest'onduct a easiility analysis
9 %ro&ect "anagementDevelop the work plan
Staf the pro&ect"onitor C control the pro&ect
Deliverale+ Work
%lan
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SDA'+ $he nalysis %hase> Develop an analysis strategy
"odel the current system
5ormulate the new system9 ather the re-uirements
Develop a system concept
'reate a usiness model to
represent+
3usiness data
3usiness processes
; Develop a system proposal
Deliverale+ nalysisand *ighE
AevelDesign
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SDA'+ $he Design %hase> Develop a design strategy
9 Design architecture and interaces
; Select hardware, sotware, networkinrastructure!
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word aout
speci.cations2/e-uirements speci.cationWhat is re-uired o the system?
*igh level
5unctional speci.cationWhat unctions must it provide?
What usiness processes must it support?
Design speci.cationDetails o design, including user interaces,
what each utton does etc
Do we need all three?
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SDA'+ $he 1mplementation
%hase
> 'onstruct the system
3uild it (write the programming code!
$est it
9 1nstall system
$rain the users; Support the system
(maintenance!
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SDA'+ "ethodologies"ethodology+ a ormaliFed approach to
implementing the SDA'
'ategories3y area o ocus%rocess orientedData centeredO&ectEoriented
3y se-uencing and emphasis o phases+Structured/apid action development
gile development
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'lasses o
"ethodologiesStructured DevelopmentWaterall Development
%arallel Development/apid pplication
Development%hased
%rototypinggile DevelopmenteGtreme %rogrammingS'/4"
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Structured "ethodologies4sed commonly in >H:s
/eplaced adEhoc approach
5ormal, se-uential, stepEyEstep
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Waterall Development%roceeds se-uentially rom one step to the ne0t
Aots o documentation, approved at each step
'anIt go ackwards
dvantages+
/e-uirements are identi.ed long eore programmingstarts
/e-uirements do not change
Disadvantages+
1 re-uirements are missed,e0pensive postEimplementation changesre-uired
Does not cater or changes in
the environment
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%arallel Developmentter a general high level design, suEpro&ects
are created
SuEpro&ects designed and implemented inparallel
SuEpro&ects integrated at the end
dvantages+
/educes time or total development, so lesschange in environment
Disadvantages+SuEpro&ects may e interdependent, so
integration is diJcult
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/apid pplication
DevelopmentStarted to e used in >HH:s
$ry to get some parts o the systemdeveloped -uickly and out to users oreedack
dvocate the use o 'omputer ided Sotware)ngineering ('S)! tools, oint pplication
Design (D! sessions, visual programmingtools, code generators
'an result in Lscope creepI # re-uirementschange and increase as users work with the
system
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%hased Development3egins with a high level design o the system concept
De.nes a series o versions, with ever increasingunctionality
5or each version, there is analysis, design,
implementation, release to users'ontinues until system complete or osolete
dvantages+ets something in the hands o the users -uickly, so early
value to organisation
'an also identiy prolems and changed re-uirements early
Disadvantages+4sers are working with an incomplete system
4ser e0pectation management
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%rototyping1terative
Mery preliminary design used to create .rst prototype
radually re.ned
nalysis, design and implementation perormed
concurrentlyll iterative
dvantages+)arly user involvement and eedack
Disadvantages+Such rapid change that methodological design and
analysis is diJcult
'an e very ineJcient
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$hrowaway %rototypingdopts a more
conventional waterallprocess overall, ut
prototypes are uilt alongthe way, then discarded
%rototypes address speci.cissues
)ach prototype has its ownanalysis, design,implementation cycle, andis used to re.ne thedesi n
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gile Development"ost recent
"ore ocussed around design philosophiesthan speci.c details o methodology
5ollow the >9 principles+Sotware is delivered early and continuously
'hanging re-uirements are emraced
'ustomers and developers work together5ace to ace communication is key
5ocus on technical e0cellence and good design
/egular reNection
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Drawacks o gile Development/e-uire coElocation o
development team
$he process i not highlymanaged (y de.nition!, so canturn into Lprogrammers gonewildI, hacking togethersolutions
Aittle documentation
Suitale or large, missioncritical systems?
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)0treme %rogramming'ommunication, simplicity, eedack,
courage
5eedack to users continuously
)mrace change
Buality .rst
$esting is continuous
)volutionary, incremental*eavy onEsite user input
/elies on a small, closeEknit team
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Scrum"ade up o ;: day sprints
)ach sprint delivers a system to the
user
6o re-uirements changes during a
sprintScrum meeting each day+%revious dayIs accomplishments
%lan or today
ny ostaclesgain, may not e suitale or large
pro&ects
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Which "ethodology to
4se?
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What kind o person is involvedin Systems nalysis?
gents o change
1dentiy ways to improve the organiFation"otivate C train others
ility to see oth technical and user sides oa prolem
3ig picture plus detail
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Skills needed or Systemsnalysis
Skills needed+ $echnical+ must understand the technology
3usiness+ must know the usiness processes
nalytical+ must e ale to solve prolems
'ommunications+ technical C nonEtechnicalaudiences
1nterpersonal+ leadership C management
)thics+ deal airly and protect con.dentialinormation
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os involving Systems nalysis3usiness nalyst5ocuses on the usiness issues
Systems nalyst
5ocuses on the 1S issues
1nrastructure nalyst5ocuses on the technical issues
'hange "anagement nalyst
5ocuses on the people and management issues
%ro&ect "anager
)nsures that the pro&ect is completed on time and withinudget
Systems rchitect
Data "odeller
4ser 1nterace71nteraction Designer
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1$ %ro&ect "anagement%ro&ect "anagement is the process o planning and
controlling system development within a speci.ed
time at a minimum cost with the right unctionality
pro&ect is a set o activities with a speci.edeginning and end point meant to create a systemthat rings value to the usiness
%ro&ect "anagers monitor and control all tasks androles that need to e coordinated
nalysis and "odelling are key to the success o 1$pro&ects
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Spectacular 1$ pro&ect
ailures4K prison 1$ system+http+77wwwFdnetcom7article7ukEprisonEitEmassiv
eEandEspectacularEailure
7See reading rom 6elson, 9:: on Stream
http://www.zdnet.com/article/uk-prison-it-massive-and-spectacular-failure/http://www.zdnet.com/article/uk-prison-it-massive-and-spectacular-failure/http://www.zdnet.com/article/uk-prison-it-massive-and-spectacular-failure/http://www.zdnet.com/article/uk-prison-it-massive-and-spectacular-failure/http://www.zdnet.com/article/uk-prison-it-massive-and-spectacular-failure/http://www.zdnet.com/article/uk-prison-it-massive-and-spectacular-failure/
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Why are ailures so
common?4nderestimating time and efort4nreasonale demands7e0pectations
4se o unknown7new technologies $oo much ocus on technology+Driven y technology rather than usiness
value
5ailing to take human, organisational, culturalaspects into account
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%ro&ect 1denti.cation usiness need is identi.ed # management,usiness unit, 1$ department, e0ternal (egpoliticians, senior management!
'ould result rom some prolem (losingmarket share etc!
Speculative pro&ect identi.cation
$he usiness need should drive the high levelre-uirements
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$he System /e-uest document that descries the reasons or and the
value added rom uilding a new system
'ontains = elements+• %ro&ect sponsor+ the primary point o contact or the
pro&ect
• 3usiness need+ the reason prompting the pro&ect
• 3usiness re-uirements+ what the system will do
• 3usiness value+ how will the organiFation ene.t romthe pro&ect
• Special issues+ nything else that should e considered
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What is a 3usiness 'ase?'ommonly (and loosely! used term to
descrie a document that &usti.es why asystem should e uilt7changed7upgraded
'an range rom a couple o paragraphs to alengthy document
1 you want to spend time or money on apro&ect, you will need to make the case to
management
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5easiility nalysis1s this pro&ect easile?What are the risks?
'an these risks e overcome?
"a&or components+ $echnical easiility ('an we uild it?!
)conomic easiility (Should we uild it?!
OrganiFational easiility (Will they use it?!
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$echnical 5easiility1dentiy risks in the ollowing areas+ $he unctional area+ re analysts amiliar
with this portion o the usiness? $he technology+ Aess amiliarity generates
more risk
%ro&ect siFe+ Aarge pro&ects have more risk
'ompatiility+ DiJcult integration increasesthe risk
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)conomic 5easiility('ostE3ene.t nalysis!
1dentiy the costs and the ene.ts
ssign values to the costs and ene.tsDetermine the cash Now
Determine the value using one or moremethods+
6et present value (6%M!/eturn on investment (/O1!
3reakEeven point
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5ormulas or Determining
Malue
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)0ample 'ostE3ene.t
nalysis
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)0ample 3reakE)ven
%oint
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OrganiFational 5easiilityWill the users accept the system?
1s the pro&ect strategically aligned with the
usiness?'onduct a stakeholder analysis%ro&ect champion(s!
OrganiFational management
System usersOthers
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%ro&ect Selection%ro&ects are approved, declined or delayed
ased on value added vs risks
%ro&ect portolio managementoals+"a0imiFe cost7ene.t ratio
"aintain an optimal mi0 o pro&ects ased on+/iskSiFe, cost C length o time to complete
%urpose, scope C usiness valueAimited resources re-uire tradeEofs
Selected pro&ects enter the pro&ectmanagement process
%ro&ect "anagement
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%ro&ect "anagement $oolsids in creating workplans
1dentiy all tasks, their se-uence and estimate thetime to complete each one
Work reakdown structures (W3S!+ a hierarchy otasks to identiy+Duration o each task'urrent status o each task $ask dependencies (shows which tasks must e
completed eore others can egin!antt charts+ horiFontal ar chart that shows the
W3S graphically
6etwork diagrams+ %)/$ and '%"
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antt 'harts
Show tasks, duration, start and end andresources (eg staf! in graphical ormat
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(ctivity
> Study conte0tual aspects that contri,ute to language use and interpretation in )nglish
9 Study use of spatial relations in "aori
; Study conte0tual aspects that contri,ute to language use and interpretation in "aori
< 'ompare )nglish and "aori spatial language models and conte0tual aspects
; Develop of Spatial 'onte0t Ontology
< Develop of model for conte0tual language use
= Develop of reasoning method
P )valuate models against test data and iteratively improve
Qear > Qear 9 Qear ;
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Scope "anagementScope RcreepOccurs ater the pro&ect is underway
/esults rom adding new re-uirements to the pro&ect
'an have a deleterious efect on the schedule $echni-ues to manage the pro&ect scope+ 1dentiy all re-uirements at the outset
llow only those changes deemed asolutely necessary
'areully e0amine the impact o suggested changesDelay some changes or Ruture enhancements
$ime o0ing
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)nvironment C 1nrastructure
"anagement
)nvironmentT'hoose the right set o tools4se appropriate 'S) tools to+
1ncrease productivity and centraliFe inormation (repository! 4tiliFe diagramsTmore easily understood
)stalish standards to reduce comple0ity
1nrastructureTDocument the pro&ect appropriately
Store deliverales C communications in a pro&ectinder
4se 4ni.ed %rocess standard documents
DonIt put of documentation to the last minute
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'ase Study+ ustralian 'apital $erritory SD"S
oal+ to automate, record, enale landadministration
$wo e0isting systems+'D system
Oracle ased te0tual system
/e-uirement+ a single integrated system tosupport all usiness unctions
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'ase Study+ ustralian 'apital $erritory SD"S
Waterall model
5irst analysed e0isting systems andprocesses
Designed new processes
Designed user interaces and applications to
support those processes
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'ase Study+ ustralian 'apital $erritory SD"S # Aessons Aearnt
"assive scope creep
"oved to phased methodology4ser involvement much too late in the
process
5ull set o speci.cations+ re-uirements,
unctional, designDesign spec impractical
Mery comple0 system technically andorganisationally
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What 6e0t?