Use Case Diagrams Describe User – System Interaction
Use Cases help us create the website that you need. They tell a story about how a website, or any system for that matter, is used by the various players who are going to interact with it. They make sure that customers are guided through every step of the checkout process and that the seller can do everything he needs to do, from introducing to new products to emailing her customers to keeping track of inventory.
The example below involves a music website:
What Are Actors and How To Define Uses Cases
Actors are the people who receive direct benefits from the “Use Cases” or stories about the business we want to model.
Names for Use Cases generally start with an action verb and then include a noun, such as “Make Deposit” for a banking Use Case.
Some Examples from a Credit Union Banking Application
Actors: Member, Teller, VicePresident
Member – Make Deposit
(secondary actors would be Tellers and ATMs – actors do not have to be human)
Teller – Check Identity
(e.g. ask for driver’s license or password – these are details we’ll get to later)
VicePresident – Interview Job Applicants
Ater the actors have been defined and basic Use Case been named, detailed steps for each Use Case have to be filled in. We can use many different tools to describe the problem we are solving and we can approach the problem in a manner such that each step is easy to describe. But keep in mind that a Use Case
- must provide some value to a primary actor
- is not a flow chart and does not show “time flow”
- does not describe things inside a system
- describes interactions between an actor and the system in an abstract manner without making reference to specific interface objects
While it takes time to create detailed use cases, doing so ensures a well laid out and usable website. Especially complex websites that many different types of visitors interact with, need this kind of preliminary analysis so that all necessary details will be taken care of.
