Outline
§ Goal diagrams
§ Lamsweerde’s notation (basic notation plus book)
Requirements modelling
§ FA/SIMM notation (appended material)
§ UML short intro (consult home page of TDDC88)
Kristian Sandahl
IDA
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Why do we do this?
Goal diagrams – Lamsweedre’s notation
§ Models supplement natural language descriptions.
§ Models increase visibility
Goal
§ Models assist elicitation
Achieve [BookRequestSatisfied]
§ Models introduce some formality
§ Models can help avoiding omission errors
§ Models can be used both for requirements and design
Type
Name
§ Linköping research: Model-based Product Development
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Linköpings universitet
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Goal diagrams – AND refinement
Goal diagrams – Complete refinement,
with agents
Achieve [BookRequestSatisfied]
Achieve [CopyBorrowed
If Available]
Achieve [BookRequestSatisfied]
Achieve [CopyDueSoonForCheckOut
If Not Available]
Achieve [CopyBorrowed
If Available]
Achieve [CopyDueSoonForCheckOut
If Not Available]
Responsibility
Loan software
Agent
Staff
Environment agent marker
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Goal diagrams – OR refinement
with obstruction
Building goal models: Heuristic rules and
reusable patterns
ComprehensiveLibraryCoverage
EffectiveBookSupply
§ Analyse current
objectives and problems
§ Search for goal-related
keywords
§ Instantiate goal
categories
§ Ask How and Why
questions
§ Split responsibilities
§ Identify soft goals
§ Identify agent wishes
AccessToForeignDigitalLibrary
Obstruction
Obstacle
IllegalCopying
Resolution
Countermeasure goal
§ Analyse obstacles
§ Check complementary
cases of conditional goals
§ Refine goals until
assignable to single
agents
§ Don’t confuse goals and
operations
§ Don’t confuse AND and
OR
§ Avoid ambiguities
TraceDownloads
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Use-case diagram
Use-case diagram for the library
Library system
Actor: a user of
the system in a
particular role.
Can be human
or system.
Name: a verb phrase
Reserve book
Browse
Borrow copy of book
BookBorrower
Detail of use-case
BookBorrower
Borrow copy
of book
Browser
Return copy
of book
A BookBorrower presents a book.
The system checks that the potential
borrower is a member of the library,
and that he/she doesn’t already have
the maximum permitted book on loan.
This maximum is 6 unless the
member is a staff member, in which
case it is 12. If both checks succeed, the
system records that this library member
has this copy of the book on loan.
Otherwise it refuses the loan.
Extend loan
Borrow journal
Update catalog
Return journal
JournalBorrower
Librarian
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Please,
Please,keep
keepas
as
simple
simpleas
aspossible.
possible.
Relations between use-cases
Extend loan
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Extension points
Condition: {customer selected HELP}
extension point: Selection
<<include>>
Check for
reservation
BookBorrower
Borrow copy
of book
<<include>>
”Reuse”
Perform loan transaction
<<extend>>
Stereotype: extended
classification of meaning
extension points:
on-line help
<<extend>>
Selection
Refuse loan
”Separating scenarious”
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Identifying classes: noun analysis
A BookBorrower presents a book.
The system checks that the potential
borrower is a member of the library,
and that he/she doesn’t already have
the maximum permitted book on loan.
This maximum is six unless the
member is a staff member, in which
case it is 12. If both checks succeed, the
system records that this library member
has this copy of the book on loan.
Otherwise it refuses the loan.
The single class model
•book – real noun handled
by the system
•system – meta-language
Book
name
•borrower – already actor
•library member – handled
by the system
title: String
•staff member – handled by
the system
attribute
copiesOnShelf() : Integer
borrow(c:Copy)
•checks – event
operations
•copy of book – handled by
the system
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The library class model
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More relations between classes
1..*
10..*
Topic
Book
Link
aggregation
Volume
composition
Square
qualified
association
1
1
is a copy of
1..*
LibraryMember
borrows/returns
0..1
0..*
Copy
Board
generalisation
MemberOfStaff 0..1
1..*
Encylopedia
is a copy of
borrows/returns
0..*
Copy
Journal
1..*
1..*
0..*
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Book
constraint
{xor}
is a copy of
Linköpings universitet
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row:{1,2,..8} 1
column:{1,2,..8}
0..*
Journal
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Combining fragments of sequence diagrams
Continue modelling :Sequence diagram
SD processOrder
theLibraryMember:
LibraryMember
theCopy: Copy
:Order
theBook: Book
:TicketDB
:Account
create
aMember:
BookBorrower
ref
Get existing customer data
borrow(theCopy)
A
1: okToBorrow
2: borrow
{C-A < 5s}
loop
{borrowed’ –
borrowed < 1s}
2.1: borrowed
loop
[get next item]
reserve(date,no)
loop condition
add(seats)
answer
C
destruction
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More fragments of sequence diagrams
:Order
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State diagram
:TicketDB
For class Copy:
start marker
object
loop
[get next item]
reserve(date,no)
alt
[available]
guard condition
nested conditional
on loan
message this object
return()/book.returned(self)
on the shelf
borrow()/book.borrowed(self)
add(seats)
alternate branches
reject
[unavailable]
state
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event, causing
transition
action, reaction
to the event
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State diagram with guards
Wiht
WihtOCL,
OCL,Object
Object
Constraint
ConstraintLanguage,
Language,this
this
becomes
becomesvery
verypowerful
powerful
For class Book:
returned()
not borrowable
returned()
borrowable
borrowed()[last copy]
borrowed()[not last copy]
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www.liu.se