Methods and Modelling

Dr Steve Wade

The Vision

Business Computing

A Dog Kennel

Can be built by one person

Requires Minimal

modeling Simple process Simple tools

A House

Built most efficiently by a team

Requires Modeling Well-defined

process Power tools

But what about a skyscraper?

Or a magnificent structure like this...

What about the contents?

Stock controlLoansReservations

An information system for the library

..is no more easy to design than the library itself

How do we model an information system before constructing it?

Modelling Information Systems

What kind of blueprints are required?

We will produce blueprints of information systems using the Unified Modelling Language

It can be used by everyone on a development project

It consists of dozens of types of drawing

Different drawings are for different peoplee.g. managers, programmers, analysts, users etc.

An Object Oriented Fairy StoryAn Object Oriented Fairy Story

A gentle introduction to the Unified Modelling A gentle introduction to the Unified Modelling LanguageLanguage

Learning the basics of UML takes many weeks (longer than courting a princess)

Most IT degrees teach UML

We shall give a flavour of the language by using a Fairy Story as an illustration

Little Red Riding Hood

A story told in rhyme involving four characters and a basket

of groceries

The Little Red Riding Hood Project, editor, "Michael N. Salda,"

in

"The de Grummond Children's Literature Research Collection, University of Southern Mississippi,"

http://www-dept.usm.edu/~engdept/lrrh/lrrhhome.htm“

And Ken Lunn School of Computing and Engineering University of Huddersfield

Acknowledgements

A long time ago, in a house near a wood,As most pretty histories go,A nice little girl lived, called Red Riding Hood,As some of us already know.One day said her mother, "Get ready, my dear,"And take to your Granny some cakes,"And a pot of fresh butter to soothe her and cheer;"Ask after her pains and her aches."

Wood

butter cake

Red Riding Hood

near

Houselives in

grocery

takes

A Class Diagram

Red Riding Hood An object

lives inA one-way relationship

near A two-way relationship

A “kind of” relationship

The Notation

Customer Order

Product

A Class Diagram for Ordering

In the design of a system, the objects and relationships are drawn as above.Systems usually contain hundreds of objects.

The Vision (with some UML Jargon)

“Soft” Systems Models

Use Cases

Interaction Models

ClassDiagrams

Programs

Databases

BusinessComputing

The story continues ...

Out set Riding Hood, so obliging and sweet,And she met a great Wolf in the wood,Who began most politely the maiden to greet,In as tender a voice as he could.He asked to what house she was going, and why;Red Riding Hood answered him all:He said, "Give my love to your Gran; I will try"At my earliest leisure to call."

Red Riding Hood

ObligingnessSweetness

Wolf

Talk()

meet

Red Riding Hood has some “attributes”, she is obliging and sweet

And the wolf has some “operations” - he can talk

And they meet in the wood, so they have a “relationship”

A Class Diagram

Customer

NameAddressTelephone Number

Order()Pay()

Order

DateTotal Price

Dispatch()Deliver()PayFor()

Product

NameItem Price

AddToStock()TakeFromStock()

1..n

1..n1..n

A Class Diagram in a Business System

How could this be implemented in software?

The story continues ...

Off he ran, and Red Riding Hood went on her way,But often she lingered and played,And made as she went quite a pretty nosegayWith the wild flowers that grew in the glade.

Red Riding Hood

ObligingnessSweetness

Linger()Play()

flowerspicks

Nosegay

makes

So RRH has operations linger and play

And she makes a nosegay

That is made of flowers that she picks

A “made of” relationship

The story continues ...

But in the meanwhile the Wolf went, with a grin,At the Grandmother's cottage to call;He knocked at the door, and was told to come in,Then he eat her up--sad cannibal!Then the Wolf shut the door, and got into bed,And waited for Red Riding Hood;When he heard her soft tap at the front door, he said,Speaking softly as ever he could:

: Bed : Wolf : Cottage : Grandma

knockrouse

enter

eat

get in

A Sequence Diagram

: Print Invoice : Sales Items : Invoice : Customer Record

GetUnbilledItems( )

PrintCustName( )

PrintCustAddress( )

PrintLines( )

PrintTotal( )

PrintTermsConditions( )

GetName( )

GetAddress( )

A Sequence Diagram to Print an Invoice

The Vision

“Soft” Systems Models

Use Cases

Interaction Models

ObjectModels

Programs

Databases

BusinessComputing

The story continues ...

"Who is there?" "It is I, your dear grandchild; I've brought"Some butter and nice little cakes.""Pull the bobbin, my child, and come in, as you ought;"I'm in bed very bad with my aches."When she entered the room, the old Wolf hid himselfVery carefully (such was his plan):"Put your basket and things, little dear, on the shelf,"And come into bed to your Gran."

Character

GrandmaWolf

Talk()Eat()

Red Riding Hood

ObligingnessSweetness

Linger()Play()

InheritanceWe have three types of character in the story So we can have a

“Character” object

And all the other characters are “types” of Character

GrandmaWolf Red Riding Hood

ObligingnessSweetness

Linger()Play()

Character

Talk()Eat()

Inheritance

Now we can group common properties in Character

All characters “inherit” the properties of Character

So both Grandma and Red Riding Hood can Talk and Eat

The story continues ...

The obedient child laid her down by the sideOf her Grandmother dear (as she thought);But all at once, "Granny!" Red Riding Hood cried,"What very long arms you have got!"He answered, "The better to hug you, my child.""But, Granny, what very large ears!""The better to hear you;" the voice was still mild,But the poor little girl had her fears."Grandmother, you seem to have very large eyes!""The better to see you, I trow.""What great teeth you have got!" and the wicked Wolf cries,"The better to eat you up now!"

Red Riding Hood shrieked, and--bang! off went a gun,And shot the old Wolf through the head;One howl and one moan, one kick and one groan,And the wicked old rascal was dead.Some sportsman (he certainly was a dead shot)Had aimed at the Wolf when she cried;So Red Riding Hood got safe home--did she not?And lived happily there till she died.

At home

At Grandma's

In bed with Wolf

At home

RRH starts life at home

Then goes back and forth to Grandma’s

Until she climbs in bed with the Wolf

Then she goes home traumatised where she stays until she dies

A Statechart Diagram

waiting dispatch

on route to customer

delivered

billed

order payed for

waiting delivery

[ goods not in stock ][ goods in stock ]

order cancelled

Statechart diagram for an order

The End

So, what have we seen?

•We can describe things graphically•We can show how things relate•We can show how things cooperate•We can show what things do

The Vision

“Soft” Systems Models

Use Cases

Interaction Models

ObjectModels

Programs

Databases

BusinessComputing

Let’s get started