System modeling - L3
– Behavioral Modeling (Chapters 6 & 7) > Use cases > Use case diagrams > CASE Tools – Structural Modeling (Chapter 8) > Class diagrams
– Behavioral Modeling (Chapters 6 & 7) > Use cases > Use case diagrams > CASE Tools – Structural Modeling (Chapter 8) > Class diagrams
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Lernkarten
What is a use case
Use cases formalize the functional requirements of a system
> Use cases describe how a system is used
> A use cases define the set of possible interactions between users and the
system
> Use cases are technology-independent
– What use case are NOT
> Use cases describe what a system accomplishes, not how
» Use case modeling is limited to a system’s external behavior
» Use cases do not model the system from inside
> Use cases are not effective in capturing the non-functional requirements
> Use cases are not inherently object-oriented
Use case building blocks
A use case has at least four components:
> One Goal
> Actors and Stakeholders
> Systems
> Scenarios
What is a system in use case
System
> The system defines the boundaries of a use case
> A use case cannot leave a system, but can reach across its boundaries
What is a scenario in use case
Scenario
> The scenario is an ordered sequence of interactions between the actor(s) and the
system to accomplish a goal.
> It consists of:
» Normal Flow
» Alternate Flow
» Sub-Flows
» Exceptions
4 steps of use case evolution
1 discovery
2 deployment
3 reorganize
4 elaborate
Organization of a use case
pre-condition
post-condition
flow of events
components of use case diagram
> System
> Actors
> Use cases
> Relationships
» Association between actors and use cases
» Generalization between actors and between use cases
» Include and extend relationships between use cases
from use cases to system structure
- Requirement
- Behavioral model
- class candidates
- conceptual classes
- structural model
relationships between classes
- generalizaiton
- association and multiplicity
- aggregation and composition
- packages
- visibilities
generalization and specialization
generalization = subclass <--> superlcass / more abstract
specialization = subclass <--> subclass / more concrete
visibility
+ public
- private
# protected
~ package
