Use Cases

Wikipedia tells us that:  A use case is a list of actions or event steps typically defining the interactions between a role (known in the Unified Modeling Language (UML) as an actor) and a system to achieve a goal. The actor can be a human or other external system.

We look at it as a written description with an accompanying diagram showing how a user will interact with your system or website,  User stories provide a valuable method to elicit requirements for a system.  Agile methodologies have made them more popular, however they can be used with any methodology.  The diagramming, in particular, offers insight into the stepwise process the user will go through and allows us to see the scope at each step.  They also help us define error conditions, what could go wrong at each step.  When it comes to preparing a test plan they are once again invaluable.  Walking back the user stories to get test scenarios is very effective and provides an effective shortcut.

The basic elements include the following:

Actor – Anyone that performs any task using the system.

Stakeholder – a person or role who has a vested interest in the behavior and outcomes of the system or website.

Precondition – What must be true before the use case runs.

Triggers – events that cause the use case to be initiated and can trigger decision points once within.

Main success scenarios – when everything works as it should.

Alternative paths – when every thing does not work as it should.

 

Lets go over a few examples:

 

Web Diagram of a Use Case. The process of order food at a restaurant.
Client orders food, waiter receives order, waiter confirms food order with chef, If wine ordered, wine served in interim. chef cooks food, waiter receives food , waiter servers food, client eats food, client drinks wine, client gives payment to waiter, cashier accepts payment from waiter, cashier completes transaction.

Title: Use case restaurant model

Author: Kishorekumar 62 (redrawn by Marcel Douwe Dekker)

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License: This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

Attribution: Kishorekumar 62

 

Prisoner automation system used by police. Access of admin vs user
Administrator authorized for: login / logout, add / delete users and entries, add complaint status, view complaint status, search prisoners. Standard user authorized for: view complaint status, search prisoners, registration of criminal, view reports and FIRs, fiew case history.

 

 

Online Shopping System
Online customer: view products, purchase products, manager customer information, create product review. Marketing admin: manage products, report product sales. Warehouse manager: manage inventory, report inventory. Payment processing system is used for purchasing of products. a warehouse clerk fulfils order

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