31269 Lecture Notes - Lecture 7: Unified Modeling Language, Use Case Diagram, Use Case
Lecture 7 – Object Oriented Modelling – Use Case Modelling
Application Models
• There are two key approaches to modelling:
o Structure Approach –
▪ Application is a collection of processes organised into a system
▪ Processes interact via flows of data
▪ Processes accept inputs and produce outputs
▪ A structured Analysis Focus have processes and data, with
process descriptions using BPMN and data descriptions using
ERDs.
o O-O Approach
▪ Application is a collection of interacting objects
▪ The objects interact with people and each other.
▪ Objects send and respond to messages/methods.
▪ An Object Oriented Analysis Focus has methods and
attributes, with the objects described using use cases,
sequences and events, classes, state transitions and a unified
modelling language.
Unified Modelling Language
• A standard language for specifying, visualising, constructing and documenting
the artefacts of software systems.
• UML 2.X is an industry standard developed to support Object-Oriented
analysis and design. It is a pictorial language used to make software blue
prints.
• The diagrams produced are made for developers, business users, common
people, and anybody interested in understanding the system.
Use Case Model and Narratives
• The development process for the use case model is:
o User Stories
o Use Case Diagram
o Use Case Scenarios or Narratives
o User Interface or Wireframe or Screenshot
• A user story can be detailed in terms of 1 or many Use Cases
• A use case diagram contains four components
o System Boundary – defines the system of interest (Scope) in relation
to the world around it
o Actors – a person, organization or external system that plays a role in
one or more interactions with the system
o Use Cases – generalised description of a set of interactions between
the system and one or more actors. The system functionalities are
captured in use cases.
o Relationships – between and among actors and the use cases.
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