Modelling Information Systems

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Modelling Information Systems

• What are we going to do ?
• And why?

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• A Greek Urn

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How can I build this bridge?
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• A Greek Philosopher

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How can I get up this mountain?
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The Vision
Computing
Business
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Implementing the Vision
Computing
Business
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A Dog Kennel

• Can be built by one person
• Requires
• Minimal modeling
• Simple process
• Simple tools

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A House

• Built most efficiently by a team
• Requires
• Modeling
• Well-defined process
• Power tools

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But what about a skyscraper?
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Or a magnificent structure like this...
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What about the contents?

• Stock control
• Loans
• Reservations

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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?

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Modelling Information Systems

• What kind of blueprints are required?

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Is this some kind of blueprint?
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What about this?
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(No Transcript)
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An Object Oriented Fairy Story
A gentle introduction to the Unified Modelling
Language
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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
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Little Red Riding Hood
A story told in rhyme involving four characters
and a basket of groceries
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Acknowledgements
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.ht
m And Ken Lunn School of Computing and
Engineering University of Huddersfield
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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."
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A Class Diagram
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The Notation
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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.
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The Vision (Complete with UML Jargon)
Soft Systems Models
Databases
Activity Models
Programs
Object Models
Use Cases
Interaction Models
Computing
Business
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The story continues ...
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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 whyRed Riding Hood answered him
allHe said, "Give my love to your Gran I will
try"At my earliest leisure to call."
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A Class Diagram
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
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A Class Diagram in a Business System
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The story continues ...
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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.
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And she makes a nosegay
So RRH has operations linger and play
That is made of flowers that she picks
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(No Transcript)
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The story continues ...
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But in the meanwhile the Wolf went, with a
grin,At the Grandmother's cottage to callHe
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 HoodWhen he heard her soft tap
at the front door, he said,Speaking softly as
ever he could
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A Sequence Diagram
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A Sequence Diagram to Print an Invoice
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The Vision (Complete with UML Jargon)
Soft Systems Models
Databases
Activity Models
Programs
Object Models
Use Cases
Interaction Models
Computing
Business
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The story continues ...
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"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."
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Inheritance
We have three types of character in the story
So we can have a Character object
And all the other characters are types of
Character
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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
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The story continues ...
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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!"
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Red Riding Hood shrieked, and--bang! off went a
gun,And shot the old Wolf through the headOne
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 criedSo Red Riding Hood got safe
home--did she not?And lived happily there till
she died.
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A Statechart Diagram
RRH starts life at home
Then goes back and forth to Grandmas
Until she climbs in bed with the Wolf
Then she goes home traumatised where she stays
until she dies
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Statechart diagram for an order
goods not in stock
goods in stock
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The End
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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

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The Vision (Complete with UML Jargon)
Soft Systems Models
Databases
Activity Models
Programs
Object Models
Use Cases
Interaction Models
Computing
Business
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Even More JargonAll these words will be
explained in future lectures
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Lets get started