Use CaseUse CaseWhat is it?

Basic DefinitionBasic Definition

Of who can do what within a system?

Purpose of use casePurpose of use case

Describe system from user’s point of view◦Describe interaction between user and system

Indicate system response to request/trigger originating outside the system (by user)◦Provide sequence of steps involved in

interaction◦Depicts functional requirements of the system

for a task (how task/goal achieved)

Focus on the user endFocus on the user end

Users◦End user◦Other systems◦Hardware devices

Why Use Case?Why Use Case?

• Complete series of events for one particular use of a system • Use case simplified from usage scenarios/usage case

Who creates use case?Who creates use case?

Who uses use case?Who uses use case?

Requirements of use caseRequirements of use case

Use case should:◦Describe what the system shall do for the actor

to achieve a particular goal.◦Include no implementation-specific language.◦Be at the appropriate level of detail.◦Not include detail regarding user interfaces and

screens. This is done in user-interface design.From http://en.wikipedia.org/wiki/Use_case#History

Applications of use caseApplications of use case

Systems designProgrammingObject-oriented designUML (unified modeling language)Wherever functional requirements need to

be capturedBusiness useSoftware use

Use case diagram (in UML)Use case diagram (in UML)

Diagram used in UML (unified modeling language) in software engineering

http://en.wikipedia.org/wiki/Use_case_diagram

Use case Use case templatetemplateSample template – see http://en.wikipedia.org/wiki/Use_case for what would go in each of fields in the right hand column of this template

Fill in descriptions

Use case name

Version

Goal

Summary

Actors

Preconditions

Triggers

Basic course of events

Alternative paths

Post conditions

Business rules

Notes

Author and date