1. System Modelling with UML objectives
Describe Unified Modeling Language (UML) in the context of Requirements Specification
Re-visit use case, class, object and sequence diagrams
Describe collaboration, statecharts, activity, component and deployment diagrams

2. Popular Design and Modelling Tool
UML
Large systems are easier to understand when you break them down into subsystems
Good modelling techniques are increasingly important as the size and complexity of systems increase
Good models promote communication among technical and non-technical workers while ensuring good solutions
requires organisation and planning
An Object-oriented perspective.
Modelling with UML

3. About it…
Was created at Rational Software by Booch, Jacobson, and Rumbaugh. The Object Management Group adopted UML as a standard in 1997.
Is a standard way to specify, construct, and document systems that use OO methods
Systems you model may be implemented in an OO programming language like Java, C++, C#
As with flowcharts, pseudocode, hierarchy charts and class diagrams, UML has its own conventions and symbols
You can the entire specification and usage guidelines from the OMG at
Modelling with UML

4. UML Diagrams Diagram Types:
Use to create top view diagrams of business processes that let you hide detail and focus on functionality
Useful with customers who are not technically oriented
Each type of diagram allow you to see a process from a different angle
Diagram Types:
Use case diagrams
Class diagrams
Object diagrams
Sequence diagrams
Collaboration diagrams
Statechart diagrams
Activity diagrams
Component diagrams
Deployment diagrams
Modelling with UML

5. UML diagrams classification
Those that illustrate the dynamic, or changing, aspects of a system, and
Those that illustrate the static, or steady aspects of a system
Dynamic:
Use case diagrams,
Sequence diagrams,
Collaboration diagrams,
Statechart diagrams,
Activity diagrams
Static:
Class diagrams,
Object diagrams,
Component diagrams,
Deployment diagrams.
Modelling with UML

6. Use case Diagrams
Shows how a system works for the perspective of those who approach it from the outside or use it
This includes many types of uses:
Employees, customers, suppliers
Governments, private organisations, machines or other systems
Easier to think of them as users,
hence the term actors
Modelling with UML

7. Use case diagram for Librarian
Represent system functions or services that are visible to the actor
Represent cases for which actors interact with system or benefit from it
Determining all cases help divide a system logically into functional parts
Establishing use cases usually follows from analysing the main events in a system
acquireNewBook()
checkOutBook()
librarian
Modelling with UML

8. Variations of use cases
Extend
Is a use case that shows functions beyond those found in the base case
Include
When a use case can be part of multiple use cases (similar to subroutine or submodule)
Generalisation
When a use case is less specific that others and you want to be able to substitute the more specific for a general one
Modelling with UML

9. <<Extend>>
Example:
Checking out a book for a new library user is slightly more complicated that checking a book out for an existing user
acquireNewBook()
checkOutBook()
checkOutBookforNewUser()
<<extend>>
librarian
Modelling with UML

10. <<include>>
Example:
Issuing a library card might be a function of checkOutBook() when library user is new
It might also be a function of registerNewUser()
acquireNewBook()
checkOutBook()
checkOutBookforNewUser()
<<extend>>
registerNewUser()
issueLibraryCard()
<<include>>
librarian
Modelling with UML

11. Use case diagram for Librarian with Generalisations
Example:
A librabry has procedures for acquiring new material, acquireNewItem() is a generalisation of acquiring specific items
acquireNewBook()
checkOutBook()
checkOutBookforNewUser()
<<extend>>
registerNewUser()
issueLibraryCard()
<<include>>
librarian
acquireNewVideo()
acquireNewJournal()
Modelling with UML

12. Use case diagram for Librarian with multiple actors
Example:
A library clerk cannot perform as many functions as a librarian; the clerk can check out books and register new library users but cannot acquire new materials.
acquireNewBook()
checkOutBook()
checkOutBookforNewUser()
<<extend>>
registerNewUser()
issueLibraryCard()
<<include>>
librarian
acquireNewVideo()
acquireNewJournal()
clerk
Modelling with UML

13. Use case diagram emphasizing actors
checkOutBook()
librarian
clerk
Library staff
Library user
Adult user
child user
Cooperating library
checkOutVideo()
checkOutReferenceMaterials()
Modelling with UML

14. Use case diagram emphasizing System Requirements
checkOutMaterials()
Library staff
Library user
Cooperating library
RemoveOldMaterialsFromSystem()
acquireNewMaterials()
Library System
reshelveReturnedMaterials()
Modelling with UML

15. Class and Object Diagrams
LibraryItem
idNum
Title
author
create()
getInfo()
Book
Video
runningTime
rewind()
Showing Generalisation
You can use a class diagram to illustrate the names, attributes, and methods of a class or a set of classes
Class diagrams are more useful to programmers (than users) because they resemble code to be developed
Modelling with UML

16. Class Diagram with association relationship
An association relationship describes the connection or link between objects that often includes information about cardinality
Example:
one Library object exists and it can be associated with any number of LibraryItem and LibraryUser. A LibraryUser can borrow up to 5 items.
LibraryItem
idNum
Title
create()
getInfo(idNum)
LibraryUser
Name
Address
borrowItem()
Library
directorName
phoneNumber
getInfo() * 1
0..*
0..5
0..1
Modelling with UML

17. Class Diagram with whole-part relationship
A whole-part (has-a) relationship describes an association in which one or more classes make up parts of a larger class (aggregation)
Library
Name
directorName
Address
phoneNumber
create()
getInfo()
PersonnelDept
deptName
Director
phoneNo
ReferenceDept
Modelling with UML

18. Object Diagrams
Are similar to Class Diagrams, but they model specific instances of classes
Library
LibraryItem
Name: University of Khartoum
directorName: Mustafa Deng
Address: Gam3a Street
phoneNumber:
idNum: 23456
Title: Software Engineering
create()
getInfo()
LibraryUser
idNum: 19564
Name: Rana Salah
Address: XXXX
Modelling with UML

19. Sequence and Collaboration Diagrams
You use a sequence diagram to show the timing of events in a single use case
the x-axis represents objects, starting from left with object or actor that begins the action
Vertical lines represents the period of time the object exists
the y-axis represents time, horizontal lines along it show how objects communicate
Collaboration diagrams emphasize the organisation of objects that participate in a system
Similar to sequence diagrams except that it contains sequence numbers to represent the precise order of activities
They show the relationships between the objects and the order of messages passed between them
Modelling with UML

20. Sequence of events from sequence diagram
BookCheckOutRecord
LibraryUser
Book
create(User idNum,
Book idNum
getInfo(idNum)
(userInfo)
(bookInfo)
(checkOutRecord)
Librarian 1. 2.
1.1
1.2
1.3
1.4
Modelling with UML

21. Example: Collaboration Diagram
Collaboration diagram uses the free-form arrangement of objects as found in an Object diagram, it is a cross between an object diagram and a sequence diagram. The diagram makes it easier to see all interactions involving a particular object.
BookCheckOutRecord
LibraryUser
Book
1. create(User idNum, Book idNum
1.1 getInfo(idNum)
1.2 userInfo()
1.3 getInfo(idNum)
1.4 bookInfo()
2. checkOutRecord()
Librarian
Modelling with UML

22. Statechart Diagrams
These show statuses (changes in behaviour) of a class or object at different points in time.
Example:
State diagram for class Book
not borrowable
returned()
borrowable
borrowed()[not last copy]
borrowed()[last copy]
guard expression …
Modelling with UML

23. contactInterLibraryLoan()
Activity Diagrams
Resembles flowcharts showing the flow of actions of a system:
Uses flowchart start and stop symbols
Use empty diamonds to represent decisions
userRequest()
retrieveBook()
contactInterLibraryLoan()
checkOutBook()
Library Owns Book
Library doesn’t Own Book
Modelling with UML

24. Activity Diagrams: Fork and Join
Many real-life systems contain activities that occur simultaneously
A fork is similar to decision but defines all branches
A join reunites control flow after a fork
memberLibraryRequestBook()
querySudanULibrary()
queryGezeriaULibrary()
sendBookToRequestingLibrary()
queryJubaULibrary()
Modelling with UML

25. Component and Deployment Diagrams
These model physical aspects of systems:
Component diagrams emphasize the files, database file, documents, and other components that a system’s software uses
Deployment diagrams focus on a system’s hardware
You use a variety of icons to symbolize software or hardware components.
Examples:
Internet Request
Table
Database
Console
Server
Printer
Modelling with UML

26. Example: Component Diagram
Internet Request
Database
Filled when a part can belong
to only one whole at a time;
Open when it can belong
to several
Library User
table
Book
table
Modelling with UML

27. Example: Deployment Diagram
Internet
Console
Printer
Server A
Server B
Modelling with UML

28. Component Diagrams in Design and Implementation
Describes the dependencies between various software components, such as executable files, documents, and source files.
A component is represented using a rectangular box, with two rectangles protruding from the left side
A Dependency is used to model the relationship between two components. The notation for a dependency relationship is a dotted arrow, pointing from a component to the component it depends on.
Component
Modelling with UML

29. Deployment Diagrams in Design and Implementation
Models the hardware used in implementing a system and the association between those hardware components. Components can also be shown on a Deployment diagram to show the location of their deployment. 
A node represents a piece of hardware in the system. This entity is represented by a three-dimensional cube.
An association, drawn as a solid line between two Nodes, indicates a line of communication between the hardware elements.
Node name
Modelling with UML

30. Examples Deployment diagram:
showing that the SiteConfig component is deployed onto the Web Server and the BaseDB component is deployed on an App Server. You can also determine that the Web Server communicates with the App Server, and the App Server communicates with the Database Server and a Printer.
Modelling with UML

31. Examples
Component diagram: identifies the MyWebComps assembly as being dependent on the BaseDB and SiteConfig source files.
You can use stereotyped icons for components instead of the standard icon
Modelling with UML

32. Deciding which UML Diagrams to use
Each provide a different view of a system
Different users have different preferences
The most important reason you use any diagram is to communicate clearly and efficiently with the people for whom you are designing the system
Modelling with UML

33. Questions