16-08-2012, 02:57 PM
Use Case Diagrams
use-case-diagrams.ppt (Size: 98 KB / Downloads: 174)
Use case diagrams describe relationships between users and use cases
A use case is a (usually high-level) user activity in the system
A use case is a collection of related success and failure scenarios that describe actors using a system to support a goal
A use case name should generally begin with a verb
Use Cases
For an example, consider an auction website (e.g. eBay)
The actor customer might:
Register for an account
Search for items by keyword
Place a bid on an item
Put an item up for auction
Check the status of this item
Actors
An actor represents a role that a user might play
For example, a network administrator at a company might play the following roles:
NetAdmin
Employee
Each role must be represented separately
A simple example
Example: In an on-line Bookstore system, user needs to log-in first before he/she could order and purchase any desired books. Describe the use case for the log-in process of the on-line Bookstore system.
Answer: For every log-in process, there are two flows
When the log-in is successful (main-flow)
When the log-in is not successful (alternate-flows)
For each flow, we can describe the sequence/flow of events.