sea side software engineering annotations annotation 13: use cases professor sara stoecklin director...
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SEA Side Software Engineering
AnnotationsAnnotation 13:
Use Cases
Professor Sara StoecklinDirector of Software Engineering- Panama City
850-522-2091
850-522-2023 Ex 182
Florida State University
Computer Science
A method to represent the user interaction with the system in a manner than communicates with users that you understand the system scenarios (business).
Video Rental System
Rent video
Customer
Return video
CorporateOrder new videos
USE CASES describe a sequence of actions (processes).
USE CASES graphically depict interactions between the system and external actors.
USE CASES identify high level services (processes, routines, methods).
USE CASES specify behavior.
USE CASES may have specialized use cases as extensions of generalized use cases.
Use Case Definition:
The specification of actions, including variant sequences and error sequences that a system, subsystem, or class can perform by interacting with outside actors.
Good way to begin defining the system through scenarios.
Test plan can be written from the users point of view with use cases.
Begins traceability.
Has extensions such as:
<<extends>> for extending the functionality of a use case
<<uses>> for using one use case within another and
<<includes>> for inner use cases and
<<calls>> for invocation of other use cases.
Difficult to determine the correct granularity.
Difficult to determine the correct use case.
Knowledge elicitation on use cases can cause an explosion of use cases.
Often too informal.
No techniques for diagramming polymorphic behavior.
• Analyze requirements.• Design the use case.• Test use case.
analysis model design model test/implement model
Video Rental System
Rent video
Rent video
Corporate
Order new videos
Order new videos
Order new videos
Order new videos
Video Rental System
Rent video
Rent video
Corporate
Order new videos
Order new videos
Order new videos
Order new videos
Rent video
Rent video
Rent video
Rent videoCuserC
ID()
Video Rental System
Rent video
Rent video
Corporate
Order new videos
Order new videos
Order new videos
Order new videos
Rent video
Rent video
Rent video
Rent video
Rent video
Video Rental System
Rent video
Customer
Return video
CorporateOrder new videos Use Case
Actor
System
SystemBoundary
Rent video
Customer
A use case may have many actorsAn Actor normally interacts with several use casesFor each actor you need to know how that actor uses the system.
Rent video
Customer
Defines 1..n actions triggered by the userRepresents an system partition (process?)Is built together with the user. Needs a description.
Narrative description Sequence Diagram as it interacts with objects.Collaboration Diagram between objects.States Diagrams
for more granularity.
Rent video
Customer
A use case description tells a user story.It contains events, actions, and states of objects.Described by the precondition, actions and post condition.defines 1..n actions triggered by the user
Rent video
Customer
Pre and Post conditions – define the values of a set of variables before and after the event triggers the actionsTrigger – event that stimulates the sequence of use case actionsActions – changes the values of the variables or as stated in OO – changes the states of the objects.
Rent video
Customer
CustomerVideo Rental System
Rent video
IdentifyValidate Identity
Identity is OK
Request movieValidate Request
Request is OK
MessageObject Operation path
Rent video
Customer
Customer
Rent video
1. Identify
2. Validate Identity
3. Identity is OK
Rent video
Customer
Identity Checking
Movie Request Checking
Wrapping Up
bad identity
Review and refine iteratively with each use case.Envision/describe/prototype each use case (user views).Release a version
when approved.
analysis model design model test/implement model
Video Rental System
Rent video
Rent video
Corporate
Order new videos
Order new videos
Order new videos
Order new videos
Video Rental System
Rent video
Rent video
Corporate
Order new videos
Order new videos
Order new videos
Order new videos
Rent video
Rent video
Rent video
Rent video
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Video Rental System
Rent video
Customer
Rent video
Corporate
Order new videos
Order new videos
Order new videos
Order new videos
Rent video
Rent video
Rent video
Rent video
Rent video
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Customer
Interfaces
Packages
Frameworks
Architectural Patterns
Design Patterns
2. Define the domain (conceptual) objects or classes of the system so domain rules (ex: business rules) can be encapsulated in these domain objects.
Video Rental System
attributes
methods
ClassName
Cassette
cassetteID: int
cassetteVolumeNo: int
rentMovie()
Customer
CID: int
name: String
authenticateCustomer ()
relationship
rents
1..*1..*
Multiplicity
Video Rental System
CassettecassetteID: int
cassetteVolumeNo: intrentMovie()
CustomerCID: int
name: StringauthenticateCustomer ()
RentalPrice\
dateofRental
ifAvail
1..*0..*1..11..10..*
Rental View Rental View Update Controller
Cassette Database
Rental Database
Customer Database
CustomerVideo Rental System
Rent video
IdentifyValidate Identity
Identity is OK
Request movieValidate Request
Request is OK
Video Rental System
Customer
Rent video
IdentifyValidate Identity
Identity is OK
Request movieValidate Request
Request is OK
e
Customer
Identify
Validate IdentityIdentity is OK
Request movie
Request is OK
CustomerDatabase
CustomerCassetteDatabase Cassette
Validate Identity
Rental
Rent
Rental ViewController
Rental View
Validate IdentityGet Identity
Validate CassetteGet Cassette
Rent video
Customer
Identify
Validate IdentityIdentity is OK
Request movie
Request is OK
CustomerDatabase
CustomerCassetteDatabase Cassette
Validate Identity
Rental
Rent
Rental ViewController
Rental View
Validate IdentityGet Identity
Validate CassetteGet Cassette
Customer
Identify
Validate IdentityIdentity is OK
Request movie
Request is OK
CustomerDatabase
CustomerCassetteDatabase Cassette
Validate Identity
Rental
Rent
Rental ViewController
Rental View
Validate IdentityGet Identity
Validate CassetteGet Cassette
Rent video
invalid customer
invalid database customer
valid database customer
valid customer
invalid cassette
valid cassette
Invalid database cassette
valid database cassette
Other Topics:
Use Case EngineeringUse Case SteroTypingUse Case Driven DesignResponsibility Driven Design