Chapter 7
The Object-Oriented Approach to
Requirements
Overview
• System analysis
-begins by defining business events and things
-business events are documented in the event table
which provides the basis for discovering the data
flows and processes that are included in the new
system
-things are documented In ERD for the traditional approach
and in class diagrams for the object-oriented approach
Overview(cont)
• Object-Oriented Viewpoint
--the world consists of objects
--Business functions are supported by a set
of objects that work together, or collaborate,
to implement the function
Object-Oriented Requirements
• Use case diagrams –show the various user roles and
how those roles use the system
• Collaboration diagram –identify which objects
collaborate, to accomplish a use case or business
function
• Message –communication between objects within a
use case
• Sequence diagram– shows the sequence of
messages among objects during a use case
• Interaction diagram– A collaboration or sequence
diagram that shows the interactions between objects
• Statechart diagram –a diagram showing the life of
an object in states and transitions
The Class Diagram
• Class Diagrams
--define the components of the system
(tell what the components make up the system)
• Use case, interaction and Statechart diagrams
--describe the behavioral aspects of the system
(tell what the components do)
The System Activities:An OO
use case/scenario view
• Use case– a single use or task performed by
the system for those who use the system
(describes an activity that the system carries
out in response to an event)
• Actor – a role played by a user of the
system.