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Humboldt University Berlin, University of Novi Sad, University of Plovdiv,University of Skopje, University of Belgrade, University of Niš, University of Kragujevac

Version: Feb. 19, 2003 (D Jan, 30, 2003)

DAAD Project“Joint Course on Software Engineering”

Topic 16Structured design

Parts of this topic use material from the textbook H. Balzert, “Software-Technik”, Vol. 1, 2nd ed., Spektrum Akademischer Verlag, 2001

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16. Structured design

a) Overview

b) Description method: Structure chart

c) Example ‚Seminar Organization‘

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no abstraction

SC: -M / C: -S:

Class abstraction

Dataabstraction

Functionalabstraction

Data-abstraction

SC: Functions/Procedures

M / C: SDL: Pascal, C,

Fortran,Cobol L85, Basic,Assembler

SC: abstractdata objects

M / C: SD after Buhr

L: Modula-2

SC: ADT (abstractdata type)

M / C: Booch,OOSD

L: Ada

SC: ClassesM / C: OODL: Java, C++

Legend: SC = System component M / C = Method / ConceptL = Programming language

0 4321

time

Structured analysis

Object-oriented analysis

Analysis method flows into the suitable design method

Structured design

Object-oriented design

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Structured design (SD): Overview

Design methods in many variants: • /Stevens et al. 74/, /Stevens 81/• /Myers 75, 78/• /Yourdon, Constantin 79/• /Page-Jones 88/

Software architecture = Hierarchy of functional components(functions, procedures, subroutines)

Description method:• Structure charts

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Basic concepts of … software developmentBalzert vol. 1, 2nd edition 2001

Function tree

Data-Dictio-nary1979

Class diagram 1980/1990

Box diagram

1973

Program flowchart

1966

Pseudocode

Decision tables

1957

Rules Petri Net1962

Sequ-encediagram

1987

Stateautomaton1954

Entity Relation-ship Model1976

Data flow diagram1966

Use Case Diagram1987

Activity diagram

1997

Collabo-ration diagram

Functional View Data-Oriented View Object-Oriented View

Algorith-mic View

Functionalhierarchy

BusinessProcess

Infor-mationFlow

Class structures

Data Structures

Rule-Based View

State-Oriented View

Controlstructures

If-Thenstructures

Entity types and relations

Finite State Automaton

Concurrentstructures

Interactionstructures

Scenario-Based View

Structure Chart

Structured Analysis

Change of description

method

Structured design

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Structured design: assessment

Software architectures that predominantly consist of functional components, are rare: • Multi-pass compilers • Numerical algorithms• etc.

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History

Edward Yourdon*30.4.1944 Software engineering consultantNew YorkCo-inventor of structured design 1979 (Book: Structured Design,together with L. L. Constantine)Pioneer of object-oriented analysis 1990 (Book: Object-Oriented Analysis,together with P. Coad).

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16. Strustured design

a) Overview

b) Description method: Structure chart

c) Example ‚Seminar Organization‘

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Structure chartGraphical representation of functional abstractions and their cooperation (call relationships, parameter passing)Example of parameter passing: function for „calculation of interest“

a p date

1

date

2

inte

rest

Interestfunctional

abstraction

in out

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unit name

call arrow

input parameter

in

in/out

out

state

calling unit

unit (sub-routine,procedure, function, operation)

transient parameter

state after execution of B

output parameter

called unitB

A

Structure chart: call structure

Clarification of call structure and data flow between units (functions)

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16. Structured design

a) Overview

b) Description method: structure chart

c) Example ‚Seminar Organization‘

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DFD 4.3: Book Presen-tations(Detail)

regi

stra

tion

data

first

invo

ice

data

personalNo

presentationNo

registration date

registration receipt

notif

icat

ion

over

book

ed

notifica

tion

false

presen

tation

notification

paying delay

first invoice

data base seminars and customers

payi

ng d

elay

part

icip

ants

cur

rent

part

icip

ants

max

pres

enta

tionN

o

regi

stra

tion

date

Invo

ice

on

rece

ipt o

n

1 Record

registrations

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Invoice data sets

Regi

stra

tion

date

Registration data = PersonalNr + SeminarNr + Registration date

Paying delay

Client

Booking

Seminar presentation

Invoice data

Recordregistrations

1Notifaction payment delayNotification overbookedRegistr

ation receipt

Notific

ation

false

pres

entat

ion

PersonalNrRegistration

data

Personal-Nr

SeminarNr

Invo

ice on

Rece

ipt o

n

Participants max

PresentationNr

Particpants

current

DFD 4.3: towards database design

data base

seminars and customers

...

Databasedesign:

Database tables

*

*

*

*

*

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Registration date

Regist

ration

date

Recordregistrations

SQL-select payment delay

SQL-select/insert booked

Enternew client

Stat

usN

ame

Adre

ssSt

atus

Pers

onal

Nr

PersonalN

rPresentationN

r Status

StatusPersonalNr Paym

ent delaySQL-select client

read registration date

Presen

tation

Nr

Person

al-Nr

Pers

onal

-Nr

Nam

eAd

ress

Provide registration receipt

Provide notificationoverbooked

Provide notificationfalse presentation

Provide notificationpayment delay

SQL-select/update presentation

Status

Presentation data

PresentationNr

Notification payment delay

Notification false presentation

Notification overbooked

Registration receipt

Structure chart: record registrations

Pre-implemented function

User interfacefunctions Database

functions User definedfunctions

Part of software architecture according to structured design

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Comments on structure chart „record registrations“ (1)

„Record registrations “ is main functionAll other functions: help functions, local functions, which are called from main functionFunctions are called from left to right

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Comments on structure chart „record registrations“ (2)

Call relations and parameter passing:• ‚read registration date‘: read from user-interface• ‚SQL: select client‘:

- Search DB for client, using key ‚PersonalNr‘found: name, address, status = trueotherwise: status = false