MELJUN CORTES Manual SAD CSCI14

8/13/2019 MELJUN CORTES Manual SAD CSCI14

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CSCI14 System Analysis and DesignInstructor: MELJUN P. CORTES

CHAPTER ITHE NATURE OF SYSTEM

What is a SYSTEM?

- It is the integration of related parts which perform a specific task.- It is a regular interacting or interdependent group of elements forming a unified

whole.

CLASSIFICATION OF SYSTEM

1. usiness System- collection of procedures! policies! methods! people! machines and other

elements which interact and ena"le the organi#ation to reach its goals.

- It is profit oriented

$. Information System- collection of procedures! programs! e%uipment and methods that process

data and make it a&aila"le to help the management for decision making.- It is knowledge oriented

FUNDAMENTAL PARTS OF A SYSTEM

Subsyste ' smaller interrelated systems ser&ing speciali#ed functions

E!"i#$! e!t ' the people! facilities! rules! policies and regulation that surrounda system

Syste %$u!&a#y ' the perimeter! or line of demarcation! "etween a system and theen&ironment

1

()*I+,)-()

S/S (- I)0 S/S (- , 0

S/S (- , )DA+/

S/S (-

su"system

su"system

su"system


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Syste I!'ut ' item that enters the "oundary of the system from theen&ironment and is manipulated "y the system

' also called #a( &ata

Syste P#$)ess ' con&ersion of inputs to outputs

' if nothing is changed! then you may not "e identifying a processSyste Out'ut ' the product that results from processing or manipulating raw data

' also called i!*$# ati$!

+ENERAL SYSTEM PRINCIPLES

' In house software 2customi#ed3 &s. Commercially a&aila"le 2general3

, longer source code is much more difficult to de"ug and maintain

' a system is di&ided into smaller su"systems which performs specific functions

' there is no perfect system! it is always "ound to some re&isions or modifications' "ecause of newer technologies a&aila"le in the market! systems are also upgrading

2

The more specialized a system is, the less able it is toadapt to different circumstances.

The larger the system is, the more of its resources thatmust be devoted

to its everyday maintenance.

System are always part of larger systems, and they can

always be partitionedinto smaller systems.

System grows


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PLAYERS IN THE SYSTEM +AME

' A communication gap separates the user from the programmer

' he system analyst translates user needs into the technical specificationsneeded "y the programmer

Syste A!a-yst ' deals concurrently with the user group! technicalprofessionals and management

Use# ' anyone who interacts with an information system in theconte t of his or her work in the organi#ation

P#$ #a e# ' concerned with the technical aspect of the de&elopmentof the system

Ma!a e e!t ' concerned with the +eturned ,f In&estment 2+,I3 and thede&elopment of schedules

Othe# Pe$'-e ' system designer! encoder! operator! technician! de"ugger!tester! trainer

3

S(+ 0+,5+A--(+Communication 5ap

S(+ 0+,5+A--(+S/S (- A)A6/S

S(+ 0+,5+A--(+S/S (- A)A6/S

-A)A5(-()


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E/ERCISES0

1. Define the term system .

$. 6ist fi&e common e amples of a system.

7. Differentiate a "usiness system from an information system.

4. Compare and contrast data and information.

8. Discuss one general system principle.

9. ow does a system analyst resol&e the gap "etween the users and the programmers;

NAME0 SECTION0INSTRUCTOR0 DATE0

4


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CHAPTER IISYSTEM ANALYSIS

What is ANALYSIS?

' study of a pro"lem! prior to taking some action- study of "usiness area and application 2to a new system3- re%uires a arget Document

Su))ess*u- A!a-ysis Phase C$ '-eti$! ea!s0

1. Selecting an optimal target$. 0roducing detailed documentation of target7. 0roducing accurate predictions of the important parameters

Cha#a)te#isti)s $* A!a-ysis

1. he work is reasona"ly straightforward$. he interpersonal relationships are not &ery complicated7. he work is &ery definite4. he work is satisfying

Ma1$# P#$b-e s $* A!a-ysis

1. Communication 0ro"lems

- instead of te t! graphics are used to communicate- point of &iew and orientation of the users and system analyst

$. Changing )ature of Computer System +e%uirements

- at least two years for any changes- trying to free#e a target document means holding or ignoring any changes

wo +easons


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8. people! more complicated- large systems re%uires more screening! more thoughts! more time consuming

9. 0olitics

a. analyst?s political situation complicated "y communication failures or inade%uaciesof his methods

solution: tools of structured analysis 2e . Inter&iews! %uestionnaires! etc.3

". changing distri"ution of power and autonomy

What is a TAR+ET DOCUMENT 3TD4?

principal product of analysis' description of a system to "e implemented' ser&es as the model of the new system

S'e)i*i)ati$! $* Ta# et D$)u e!t

S(+ S/S (- A)A6/S D(*(6,0-() (A-

- "ridging the gap with the use of arget Document- &isually represented "y te tual > graphical description- the "usiness of putting arget Document together and getting it accepted "y all

parties- it should "e transparent to the reader - it should help the &endor product the system?s "eha&ior

ESTIMATION

5 Ma1$# Thi! s that Nee&s Esti ati$!0

1. 0eople ' ow many;20rogrammers>system analyst>designers>etc.3$. Schedule ' ow long; 2 ime =actor37. Staffing Schedule '


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SYSTEM ANALYSIS

What is SYSTEM ANALYSIS?

- the scientific study of the systems process! including in&estigation of inputs andoutputs! in order to find "etter! more economical and more efficient means ofprocessing

- to impro&e the producti&ity of the system

A&"a!ta es $* Syste A!a-ysis

1. 5reater (fficiency$. -a imi#ing 0rofits7. +esources used to the "est ad&antage4. +eduction of human effort8. =aster turnaround9. +educing or eliminating errors in data and informationB. Consistent operations and procedures

Li itati$!s $* Syste A!a-ysis

1. Some "usiness pro"lems are "eyond the scope of system analyst techni%ues$. System analysis efforts cost time and money7. he human element can cause complications4. (ffort is re%uired to sell a system

What is a SYSTEM ANALYST?- the one who uses his knowledge and skills to sol&e computer pro"lems and

helps an organi#ation to reali#e the ma imum "enefit from its in&estment ine%uipment! personnel and "usiness process.

7ua-ities $* a Syste A!a-yst

1. 0ro"lem sol&er $. 5ood Communicator 2"oth written and &er"al37. Systematic4. echnically updated

8.


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$. echnical Skills- an analyst must "e aware of modern computer systems! programming and

software concepts and the kinds of personnel needed to staff computer andinformation systems

7. -anagement and Interpersonal Skills

- an analyst must ha&e good communication skills and "e a"le to articulateconcepts clearly. e must also "e a"le to put ideas and concepts in writing ina clear and understanda"le form.

Res'$!sibi-ities $* the Syste A!a-yst

1. ser 6iaison he makes aware how the system will work

$. echnical =easi"ility ' he studies the specifications>re%uirements "oth forhardware and software

7. (conomic =easi"ility ' he studies the relati&e cost and "enefit of the system

4. ,perational =easi"ility ' he studies the possi"ility of implementation

8. (stimation ' he assesses the cost! duration and manpower needed inthe pro ect

8

8!$(-e& e $*%usi!ess

usiness 0racticesand 0rocedures

Te)h!i)a- S6i--s

ardware!Software and0rogramming

Concepts

Ma!a e e!t9

I!te#'e#s$!a-S6i--s

Communication Super&isionConcepts


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E/ERCISES0

1. Discuss the importance of the analysis phase in system de&elopment.

$.


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CHAPTER IIITOOLS OF THE SYSTEM ANALYST

Syste De"e-$' e!t Li*e Cy)-e 3SDLC4- A step "y step approach to sol&ing "usiness pro"lems

8e!&a-- a!& 8e!&a--:sSyste s De"e-$' e!t Li*e Cy)-e

PHASE ACTI;ITIES PEOPLE IN;OL;ED OUTPUT1. Identifying

0ro"lems!,pportunities

and ," ecti&es

- o"ser&ing! inter&iewing- summari#ing the knowledge

o"tained- estimating the scope of

pro ect- documenting the result

- system analyst- users- management

- 0ro"lemDefinition

$. DeterminingInformation+e%uirement

- sampling! in&estigating harddata > company reports

- conduct inter&iews >administer %uestionnaires

- system analyst- users- operations

manager

- the details of thecurrent systemfunctions of the"usiness under

1. Identifying problems, 2. DeterminingOpportunities, nd Inform tion re!uirementsOb"e#ti$es

7 % Implementing 3. &n ly'ingnd e$ lu ting t(e system

system needs

4. Designing t(e re#ommended system 6 % )esting nd * int ining

)(e system

5. De$eloping nd Do#umenting +oft re

1


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study 2how; work flow

- system analyst - System -odels

4. Designing the+ecommend'ed System

- de&ising the user interface!files and data"ases that willstore much of the dataneeded

- system analyst- system designer

' ser Interface2%uestions answers! on screenmenus! graphics3

8. De&eloping DocumentingSoftware

- coding of programs >modules

- de&elopment ofdocumentation 2proceduralmanuals! online help! Ereadme filesF

- system analyst- programmer

- 0rograms >-odules >-anuals

9. esting -aintainingthe System

- series of tests to pinpointpro"lems with the sampledata first e&entually with theactual data from the currentsystem

- updating of programs

- system analyst- programmer >

de"ugger - tester

- re&ised codes >modules >programs

B. Implementing (&aluating

the System

- in&ol&es training the users tohandle the new system

- con&erting files from oldformats to new one

- installing e%uipment- e&aluation of the new

system

- system analyst- users- management- system trainers

' 1GGH runningsystem

St#u)tu#e& Syste A!a-ysis

- a method for descri"ing system using figures and flow lines rather than written narrati&es.

T$$-s $* St#u)tu#e& A!a-ysis

1. -odeling System =unctions e . Data =low Diagram$. -odeling Stored Data e . (ntity +elation Diagram7. -odeling 0rogram Structure e . 0rogram =lowchart4. -odeling ime e . 5antt Chart

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Syste M$&e-

- representation of an in placed system or proposed system that descri"es the data flowthroughout the structure

Uses $* Syste M$&e-i! T$$-s1. o focus on important system features$. o discuss changes and corrections to the user?s re%uirements with low cost and minimal risk7. o &erify that the system analyst understand the user?s en&ironment and has documented it

for the system designers and programmers can "uild it.

Syste M$&e-i! T$$-s

Information pipes connect e ternal entities! process and data store elements' can "e one way or two ways

N$tati$! Na e E>a '-e

(ntity

=low 6ine Student )o!

0rocess

Data Store

12

Student

1.GSa&e

+ecordD1 Student =ile


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+ui&e-i!es *$# C$!st#u)ti! a C$!siste!t DFD

a. A&oid infinite sinks "u""le process that has inputs "ut no outputs.

". A&oid spontaneous generation processes processes that ha&e outputs "ut no inputs

c. eware of unla"eled flow lines and unla"eled processes and data store

d. A&oid hanging flow lines

e. A&oid connecting the entity with the data store! entity with another entity and data store withdata store

De"e-$'i! Data F-$( Dia #a s Usi! T$' D$(! A''#$a)h 3+e!e#a- t$ S'e)i*i)4

1. -ake a list of "usiness acti&ities and use it to determine the:

( ternal entitiesData =lows0rocessesData Store

13

0rocess

0rocess

Data Store(ntity (ntity (ntity

Data Store Data Store


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$. Create a Conte t Diagram which shows ( ternal (ntities and Data =lows to and from thesystem. Do not show any detailed processes or data stores.

7. Draw a 0arent Diagram! the ne t le&el. Show processes! "ut keep them general. Showdata stores at this le&el.

4. Create a Child Diagram for each of the processes in the 0arent Diagram

8. Check for errors and make sure the la"els you assign to each process and data flow aremeaningful

C$!te>t Dia #a 3Le"e- 4 An o&er&iew! which includes "asic input! the general system and the output!

ird?s eye &iew of data mo&ement on the system and the "roadest possi"leconceptuali#ation of the system

he highest le&el in a data flow diagram and contains one process! representingthe entire system

he process is gi&en the num"er G 2#ero3.

E>'-$&e& Dia #a-ore detailed than the Conte t Diagram "y Ee ploding the diagramsF

a. Pa#e!t Dia #a 3The Ne>t Le"e-4Inputs and outputs in the first diagram remains constant! howe&erthe rest of the original diagram is e ploded into close upsin&ol&ing 7 to processes and showing data stores and new lowerle&el data flows(ach process is num"ered with an integer.

b. Chi-& Dia #a 3M$#e Detai-e& Le"e-4(ach process in 0arent Diagram may in turn "e e ploded to createa more detailed child diagram

he processes on the child diagram are num"ered using theparent process num"er! a decimal point and a uni%ue num"er foreach child process

@0rimiti&e 0rocess a process that cannot "e e ploded anymore

E>a '-e $* Data F-$( Dia #a

14

Su a#y $* %usi!ess A)ti"ities *$# C$ 'ute#i@e& E!-ist e!t Syste

A. he student encodes his student num"er and password which will "e&erified in the Student Data"ase.

. he a&aila"le su" ects are then displayed which are located at the Su" ectSchedule Data"ase

C. he student chooses his su" ects which is stored in the (nlist Data"aseD. he student has the option of canceling his enlisted su" ects. he

cancellation is sa&ed in the (nlist Data"ase(. he printed form which contains the su" ects enlisted is gi&en to the student.


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The C$!te>t Dia #a

The E>'-$&e& Dia #a

. ENTITY RELATIONSHIP DIA+RAM 3ERD4

15

Student .

informationStudent

0rinted form

Student

G

Computeri#ed (nlistment

System

8.G

0rint=orm

D1 Student =ile

Student

information

Student *alid password

$.GDisplay

A&aila"le

Su" ects

1.G

*erify6ogin

Schedule of Su" ects

D$ Su" . Sched=ile

A&aila"le su" ects

(nlisted su" ects

(nlistedsu" ects

Cancelled su" ects

D7 (nlist =ile

(nlisted su" ects

Student information

4.G

CancelSu" ect

0rinted form

7.G(nlistSu" e

ct


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- Depicts the relationship "etween data o" ects.- A notation that is used to conduct data modeling acti&ity- he attri"utes of each data o" ect noted in the (+D can "e descri"ed using data o" ect

description.

E!tity , the element that makes up an organi#ational system

, may "e a person! a place! a thing! an e&ent.

( ample: passenger on an airplane! a destination! a plane! sales period

Re-ati$!shi' , the association that descri"es the interaction among the entities

Di**e#e!t Ty'es $* Re-ati$!shi'

a. one to one

". one to many

c. many to one

d. many to many

Di**e#e!t Ty'es $* E!tities

a. =undamental (ntity usually a real entity: a person! place! or thing

16

Student

teach

(mployee has(mployee)um"er

eacher teaches

Student

0rogrammer Isassign

ed

0ro ect

Destination


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( .

". Associati&e (ntity something created that oints two entities

( .

c. Attri"uti&e (ntity something useful in descri"ing attri"utes! especially repeatinggroups

( .

B. DATA DICTIONARY , a repository that contains description of all o" ects consumed or produced "y software.

, it is an organi#ed listing of all data elements that are pertinent to the system! with precise!definitions so that "oth user and system analyst will ha&e common understanding ofinputs! outputs! component of stores and intermediate calculations

' created "y e amining and descri"ing the contents of the data flow! data stores andprocesses.

Sy b$-s use& i! )$!st#u)ti! a Data Di)ti$!a#y

Sy b$- Na e N$tati$! Mea!i!(%ual J Is composed of 0lus K Andraces L M )th +epetition

rackets N O P (ither > ,r Situation

17

makes a reser&ation

makes a "ooking for 0atron Concert>Show

Ass$)iati"e

E!tity

makes a reser&ation

makes a "ooking

Is for a

holds0atron Concert>ShowRese

#,"ati$

n

Attri"uti&e(ntity

elongs to

has

makes a reser&ation

makes a "ooking

Is made for

has0atron Rese

#,"ati$

n

0erformance

Concert

> Show


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0arenthesis 2 3 ,ptional (lement

E>a '-e0

1. Student Information J Student )um"er K Student 0assword$. (nlisted Su" ect J Su" ect Code K Su" ect Description K Su" ect Schedule

7. Su" ect Schedule J Su" ect ime K Su" ect +oom

5. FLOWCHART

, a graphic representation of the steps in the solution of a pro"lem in which sym"olsrepresent operations! data flow! hardware and the system plan.

Ty'es $* F-$()ha#t

a. Syste F-$()ha#t diagrams illustrate the mo&ement of data in an organi#ation. hey showthe se%uence of process through which information mo&es.

' documents the o&erall system

b. P#$ #a F-$()ha#t shows the se%uence of steps performed in a computer program' deals with the information flow through the computer

M$st C$ $!-y Use& Sy b$-s

Sy b$- Use E>a '-e

Computer 0rocess

0redefined 0rocess

Input > ,utput

Decision Y N

erminator

Connector

-anual 0rocess

18

Compute)et 0ay

CallCompute(arnings+outine

+ead arecord

Q R1G

(5I)

A A

6ogname


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=low 6ines

0rinter 2document > report3

Secondary storage >Data"ase

E>a '-e $* Syste F-$()ha#t

19

Daily imesheets

(mployeeData"ase

(5I)0A/+,66 S/S (-

Super&isorsu"mittime

sheets

ime Sheets

0roduce payroll checksand register

(mployeeData"ase

6ognum"erof lastcheck

0ayroll

register

0ayroll checks

Distri"utechecks toemploye

es

()D0A/+,66 S/S (-


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E>a '-e $* P#$ #a F-$()ha#t

2

(5I) 0A/+,66C (C 0+,5+A-

Call Input Data

Call Compute5ross (arnings

Call Compute)et 0ay

Call ,utput

()D 0A/+,66C (C 0+,5+A-

A

C

D

A

+ead(mployee+ecord

(nd of=ile;

(QI

Compute gross pay2hours @ rate3

(QI

C

CalculateDeductions

Computenet pay

2gross pay deductions3

(QI

D

pdate(mployeeData"ase

0rint0ayrollCheck

(QI


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. Hie#a#)hi)a- I!'ut P#$)ess Out'ut 3HIPO4

an attempt to pro&ide programmers with "etter structured tools for dealing with systems

TYPES0

a. ;isua- Tab-e O* C$!te!ts 3;TOC4 chart shows a hierarchy in which le&el of detailincreases from the top of the chart to the "ottom! mo&ing from general to specific.

his is called opDown De&elopment

b I!'ut P#$)ess Out'ut 3IPO4 , chart shows the processing acti&ity for any gi&enmodule in the *isual a"le ,f Contents.

b.


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22

1.G

FILE

1.1

NEW

1.$

OPEN

1.7

SA;E

1.8

E/IT

1.4

PRINT

$.G

EDIT

$.1

UNDO

$.$

COPY

$.7

CUT

$.4

PASTE

7.G

;IEW

7.1

TOOL%AR

7.$

NORMAL

7.7

OOM

4.GFORMAT

4.1

FONT

4.$

TA%S


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E>a '-e $* a! I!'ut P#$)ess Out'ut

A. IPO O"e#"ie( Dia #a

INPUT PROCESS OUTPUT

%. IPO Detai-e& Dia #a

23

8.G

HELP

8.1

A%OUT

ey"oard-ouse Click

Data

Automated


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E>a '-e $* a Wa#!ie# O## Dia #a

. +ANTT CHART

' introduced "y enry 6. 5antt' a scheduling tool that diagrams starting and ending dates of tasks' marks off time periods in days! weeks or months! thus the system de&elopers can see at

a glance what acti&ities are to "e performed! when each "egins and when eachterminates

( ample of a 5antt Chart

AC I*I I(S Sept ,ct )o& Dec an =e" -ar Apr -ay un ul Aug


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1!$!70rogram0lanning 0rogram

6isting 0rogram

De"ugging

+e&ision +e&ision

,ral Defense =inal +e&ision

E/ERCISES0

Create the different system modeling tools for the gi&en 0ayroll System.

1. Data =low Diagram 2conte t and e ploded diagram3$. Data Dictionary7. System =lowchart4. 0rogram =lowchart

25

List $* %usi!ess A)ti"ities $* a Pay#$-- Syste

A. (ach employee has an (mployee ime +ecord which will "e stored in an(mployee ime =ile.

. (mployee ime =ile and (mployee -aster =ile is then looked up to calculatethe 5ross 0ay.

C. Calculate the


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NAME0 SECTION0INSTRUCTOR0 DATE0

CHAPTER I;FEASI%ILITY STUDY

A feasi"ility study "egins with pro"lems or with opportunities for impro&ement within a "usinessthat often comes up as the organi#ation adapts to change.

A. P#$b-e s (ithi! the O# a!i@ati$!

T$ i&e!ti*y P#$b-e s L$$6 *$# S'e)i*i) Si !s0Check output against performance criteria ' oo many errors

'


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- Is possi"le to accomplish with present organi#ational resources in the following threeareas:

Te)h!i)a- Feasibi-ity Add on to present system echnology a&aila"le to meet user?s needs

E)$!$ i) Feasibi-ity Systems analysts? time Cost of systems study Cost of employees? time for study (stimated cost of hardware Cost of packaged software>software de&elopment

O'e#ati$!a- Feasibi-ity


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MELJUN CORTES Manual SAD CSCI14