Use Cases / Scenarios

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A use case is a written description of how users will perform tasks on your website. It outlines, from a user’s point of view, a system’s behavior as it responds to a request. Each use case is represented as a sequence of simple steps, beginning with a user’s goal and ending when that goal is fulfilled.

Elements of a Use Case

Depending on how in depth and complex you want or need to get, use cases describe a combination of the following elements:

  • Actor – anyone or anything that performs a behavior (who is using the system)
  • Stakeholder – someone or something with vested interests in the behavior of the system under discussion (SUD)
  • Primary Actor – stakeholder who initiates an interaction with the system to achieve a goal
  • Preconditions – what must be true or happen before and after the use case runs.
  • Triggers – this is the event that causes the use case to be initiated.
  • Main success scenarios [Basic Flow] – use case in which nothing goes wrong.
  • Alternative paths [Alternative Flow] – these paths are a variation on the main theme. These exceptions are what happen when things go wrong at the system level.

How To Write a Use Case

Write the steps in a use case in an easy-to-understand narrative. Kenworthy (1997) outlines the following steps:

  1. Identify who is going to be using the website.
  2. Pick one of those users.
  3. Define what that user wants to do on the site. Each thing the use does on the site becomes a use case.
  4. For each use case, decide on the normal course of events when that user is using the site.
  5. Describe the basic course in the description for the use case. Describe it in terms of what the user does and what the system does in response that the user should be aware of.
  6. When the basic course is described, consider alternate courses of events and add those to “extend” the use case.
  7. Look for commonalities among the use cases. Extract these and note them as common course use cases.
  8. Repeat the steps 2 through 7 for all other users.