© Minder Chen, 1999-2002 Structured design - 1 Produce Paycheck Retrieve Employee Record Global Data Store Offpage Calling Module Called Module System

© Minder Chen, 1999-2002 Structured design - 1Structured design - 1

Produce Paycheck

Retrieve Employee

Record

Global Data Store Offpage

Calling Module

Called Module

System Device

Module

Module Name

Normal Procedure (Subroutine) Call

Module Name

Library(Predefined) Module

Global Data Store Used by Page-Jones

Offpage

Used by Page-Jones

Sender

Receiver

Control Flag

DataData

Structure Chart NotationsStructure Chart Notations


Module Module1 ' The argument x is passed by value ' The argument y is passed by reference Public Sub ABC(ByVal x As Integer, ByRef y As Integer) ' If ABC changes x, the changes do not affect a. ' If ABC changes y, the changes affect b. x = x + 1 y = y + 1 End Sub

Public Sub Main() Dim a As Integer = 3 Dim b As Integer = 4 ABC(a, b) ' Call the procedure. Console.WriteLine("a = " & a) Console.WriteLine("b = " & b) ' You can force parameters to be passed by value, regardless of how ' they are declared, by enclosing the parameters in extra parentheses. ABC((x)) End Sub

End Module


Dim a As Integer = 3Dim b As Integer = 4ABC(a, b)Console.WriteLine("a = " & a)Console.WriteLine("b = " & b)

Public Sub ABC(ByVal x As Integer, ByRef y As Integer) x = x + 1 y = y + 1End Sub

x y

3a

4b

3x

y

3

5

Before After

Before After

4


A

A,1 A,2 A,3

Call A,1Call A,2Call A,3

SequenceStructured Chart NotationsStructured Chart Notations

A

A,4A,3A,2A,1

Call A,1IF Tx-Code = “A” Then Call A,2ELSE IF Tx-Code = “B” Then Call A,3

ELSE IF Tx-Code =“C” THEN Call A,4

Decision

A

A,1 A,2 A,3 A,4

Call A,1Repeat

Call A,2Call A,3Call A,4

Until EOF = “true”

AA

A,3A,3A,1A,1 A,2A,2 Statement X Statement T Statement Z

Statement X Statement T Statement Z

Call A,1 Statement X Statement Y StatementZ Call A,3

Call A,1 Statement X Statement Y StatementZ Call A,3

IterationIteration Lexical InclusionLexical Inclusion


Structured Chart Notations (Contd.)Structured Chart Notations (Contd.)

Notations used by Page-JonesNotations used by Page-Jones

DecisionDecisionIterationIteration

Lexical Inclusion (The Hat Symbol)

Lexical Inclusion (The Hat Symbol)


Structure Chart NotationsStructure Chart Notations

Interface Table

I/F# Input Output

1 A,B C

2 X Y,Z

Interface Table

1 2

Asynchronous Activation of a Subtask

Concurrent Activation Symbol

Information Cluster

A B C

D

Modules A, B, and C has exclusive access to Data D

Program X

Physical Packaging Boundary


Sample Structure Chart 2.0 Enter Customer payments

2.5 Display Customer payment

2.32 Verify Customer account

2.21 Get Customer record

2.11 Key invoice remittance

2.4 write Customer payment transaction

2.3 Update A/R master

2.2 Add Customer information

2.1 Key remittance

2.33 Rewrite A/R record

2.22 Verify Customer account

2.31 Get receivable record

2.12 Key monthly statement remittance

Structure chart for program 2.0. Enter customer payment Exercise - 3

Remittance

EOT

Customer-ID

Invoice-remittance

Monthly-Statement-remittance

Customer-sold-to-name

Remittance

Remittance

Customer-sold-to-name

Customer-payment

Customer-ID

Customer-ID

Customer-IDCustomer-number

Customer-record

Customer-record

No-record-on-file

Valid-account

A/R-record

Old-A/R-record

New-A/R-record

No-record-on-file

Valid account

Posting-ok


How would you partition this system?How would you partition this system?


Type of Coupling

Tightness of Coupling

Goodness of Design

Normal Coupling

Data Coupling Stamp Coupling

Control Coupling

Common Coupling

Content Coupling

Loose

Tight

Good

Bad


Normal CouplingNormal Coupling

A .

Call B .

A .

Call B using X,Y

.

B B

Module A and module B are normally coupled if - A calls B- B returns to A

All information passed between them are through parameter passing

XX YY


UPDATE CUSTOMER

MASTER FILE

GET VALID INPUT

VALIDATE CUSTOMER

TRANSACTION

UPDATE MASTER

PUT CUSTOMER

MASTER

GET INPUT

GET CUSTOMER

MASTER

GET CUSTOMER

TRANS

Transaction

Transaction

Transaction is valid

Transaction

Master Record

Master Record

Acct Number

Master Record

Updated Master RecordMaster

RecordValid Trans-action

Updated Master Record

Valid Trans-action


Data CouplingData CouplingCalculate

Monthly payment

of a House

Calculate Mortgage

Payment

Mortgage PaymentLoan Amount

Term

Interest Rate

Module A and module B are data coupled if - A calls B - B returns to A - All information passed between them are through parameter passing - Each parameter is a data element


Stamp CouplingStamp Coupling

Calculate

Monthly Payment

of a House

Calculate

Mortgage

Payment

Mortgage PaymentCustomer Loan Record

Two module A and B are data coupled if - A calls B - B returns to A - All information passed between them are through parameter passing - A composite piece of data is passed from one module to another


Control CouplingControl Coupling

Produce

paycheck

Retrieve Employee

Record

Produce

paycheck

Retrieve Employee

Record

Employee ID

Employee Record Employee Record

Employee ID

Tell the operator that “The Employee Record Is Not Found”

Employee Record Not Found

Control Flag Descriptive Flag


Scale of CohesionScale of Cohesion

Types of Cohesion Visibility Strength of Cohesion Maintainability

Functional Black box

Functional Black box Sequential Not-quite soSequential Not-quite so

Communicational black boxCommunicational black box

Procedural Gray Procedural Gray

Temporal boxTemporal box

Logical TransparentLogical Transparent

Coincidental or white box Coincidental or white box

StrongStrong

WeakWeak

GoodGood

BadBad


Structure Chart and DFD Structure Chart and DFD

This module is sequentially cohesive.This module is sequentially cohesive.

This module is communicationally cohesive.This module is communicationally cohesive.


Simplify Communicational Cohesion Simplify Communicational Cohesion

Get Employee Name

Calculate YTD Total Deduction

Get Employee Name

Calculate YTD Total Deduction Get Employee Name Get Employee Name Calculate YTD Total DeductionCalculate YTD Total Deduction

Employee NameEmployee Name

Employee YTD Total Deduction


Employee IDEmployee ID Employee IDEmployee IDEmployee IDEmployee IDEmployee YTD Total Deduction


Employee NameEmployee Name


Determine Module CohesionDetermine Module CohesionType of Cohesion Type of Cohesion

Does activities performed by the module related to a single problem-related task

Does activities performed by the module related to a single problem-related task

What relates the elements within the module ?

What relates the elements within the module ?

Neither data nor control

Neither data nor control

Is sequence important ?


DataData

Flow of control

Flow of control



Are the activities performed by the elements in the same category?

Are the activities performed by the elements in the same category?

YESYES

YES YES

YESYES

NONO

NONO

NONO

FunctionalFunctional

SequentialSequential

CommunicationalCommunicational

ProceduralProcedural

TemporalTemporal

LogicalLogical

CoincidentalCoincidental


DETERMINE CUSTOMER

DETAILS

DETERMINE CUSTOMER

DETAILS

Customer Account Number

Customer Name

Customer Loan Status

Customer Loan Status



Customer Name

Customer Name

A Communicationally Cohesive Module at the Bottom of a Structure Chart

A Communicationally Cohesive Module Halfway Up a Structure Chart

Each of These Functionally Cohesive Module is at the Bottom of a Structure

Customer Name


EVALUATE LOAN

STATUS

FIND CUSTOMER

NAME


A Functionally Cohesive Module Very High in a Structure Chart

Satellite Trajectory

Elevation

Ranges

AzimuthsTimes

GET RANGES

GET TIMES

GET AZIMUTHS

GET ELEVATION

GET SATELLITE

TRAJECTORY


The Impact of Module Numbers on CostThe Impact of Module Numbers on Cost

Inte

rmodule

Effe

cts (

Coupling)

Cost Due to

Cost Due toIntramodule Effects (Cohesion)

High

Low

Co

st

Number of ModulesSmall Large


Four Basic Types of ModulesFour Basic Types of Modules

Coordinate control

Transform (Process)

Transform (Process)

Efferent (Output)

Efferent (Output)

Afferent (Input)


Idea System Shape of a Structure ChartIdea System Shape of a Structure Chart

Afferent branch

Transform branch

Efferent branch


Boulding’s Explanation of GST

"(General Systems Theory) does not seek, ofcourse, to establish a single, self contained'general theory' of practically everything whichwill replace the theories of particular disciplines.Such a theory would be almost without content,for we always pay for generality by sacrificingcontent, and we can say about practicallyeverything is almost nothing. Somewhere howeverbetween the specific that has no meaning and thegeneral that has no content there must be, foreach purpose and at each level of abstraction, anoptimum degree of generality. It is the contentionof the General Systems Theorists that thisoptimum degree of generality is not alwaysreached by the particular sciences."

Source: http://cimru.nuigalway.ie/david/pdf/SE/Slides/Theory.PDFSource: http://cimru.nuigalway.ie/david/pdf/SE/Slides/Theory.PDF


Idea System Shape of a Structure ChartIdea System Shape of a Structure Chart

High fan-outHigh fan-out

High fan-inHigh fan-in


The Procedure of Deriving Structure Charts from Data Flow Diagrams

The Procedure of Deriving Structure Charts from Data Flow Diagrams

Evaluate a detailed DFD

Type of DFD

Identify central transform of the DFD

Map to transaction structure Map to transform structure

Refined the Structure Chart

Identify transaction types and transaction center of the DFD

Transaction Analysis Transform

Analysis


P

OUTPUTFUNCTION

C

P

INPUTFUNCTION

B

P

INPUTFUNCTION

D

P

OUTPUTFUNCTION

A

P

INPUTFUNCTION

C

POUTPUT

FUNCTIONB

P

TRANSFORMFUNCTION

A

P

TRANSFORMFUNCTION B

P

INPUTFUNCTION

A

BOUNDARYB

BOUNDARYA

D DATA STORE D

D DATA STORE B

D DATA STORE E

M

L

K

J

I

H

G

F

E

D

C

B

A

Afferent

CentralTransform

Efferent

Transform Analysis


TRANSFORMFUNCTION

A

TRANSFORMFUNCTION

B

INPUTFUNCTION

A

INPUTFUNCTION

D

INPUTFUNCTION

B

OUTPUTFUNCTION

A

INPUTFUNCTION

C

OUTPUTFUNCTION

C

BOSS

CENTRALTRANSFORMCONTROLLER

OUTPUTFUNCTION

B

E & F

J & I

J

G & H

E, F, & GI

J

G

I

F

K

E

C


Transaction Analysis

DFD

Get Customer Transactio

n


n


nGet

Customer Transactio

n Get Customer Transactio

n

Process Customer Transaction

Change Customer

Record

Add New Customer

Get Customer

Transaction

Delete Customer

Record

Tx-Code

Structure Chart

Customer Information System Main Menu

1. Add New Customer 2. Change Customer Record 3. Delete Customer Record

A Transaction Selection Screen


Determine Implementation BoundariesDetermine Implementation Boundaries

ManualManualReal-timeReal-time

Batch

On-line


Processor Model: Allocation of essential Model Components to Processors

Essential Model

Processor 1

Processor 2

Processor 3

Processor Level Implementation Model

Netware LAN

UNIX Server

T1

TCP/IP

Mainframe

Allocating processes and data stores to

processors


Source: Developing Web Applications with Microsoft Visual Basic .NET and Microsoft Visual C# .NET

Testing• Test plan objectives

– Is thoroughly tested– Meets requirements– Does not contain defects

• Test plan covers– Tools– Who– Schedule– Test result analysis– What is being tested?

• Test cases• Automated testing

– Reproducible – Measurable


Stubs and Drivers

Driver

Module 1 Module 2

Module M

Stub Module 2

• Stubs Stubs are non-functional components that provide the class, property, or method definition used by the other component. Stubs are a kind of outline of the code you will create later.

• To test two components that need to work together through a third component that has not been written yet, you create a driver. Drivers Drivers are simply test components that make sure two or more components work together. Later in the project, testing performed by the driver can be performed by the actual component.

The most common build problem occurs when one component tries to use another component that has not yet been written. This occurs with modular design because the components are often created out of sequence.


Test type Objectives

Unit testEach independent piece of code works

correctly

Integration test

All units work together without errors

Regression test

Newly added features do not introduce errors to other features that are already working

Load test (also called stress test)

The product continues to work under extreme usage

Platform testThe product works on all of the target

hardware and software platforms

Types of Tests


Regression and Regression Test

• Regression testing is the process of validating modified parts of the software and ensuring that no new errors are introduced into previously tested code.

• Unit and integration tests form the basis of regression testing. As each test is written and passed, it gets checked into the test library for a regularly scheduled testing run. If a new component or a change to an existing component breaks one of the existing unit or integration tests, the the error is called a regression.error is called a regression.



Documents

© Minder Chen, 1999-2002 Structured design - 1 Produce Paycheck Retrieve Employee Record Global Data Store Offpage Calling Module Called Module System