Use Case And Example

                              USE CASE

A use case is a methodology used in a requirement engineering process to identified and clarify a system requirement. A use case shows an interaction between end user and system. Use case is a description of how users interact with a system and perform a particular task. Each use case tells that how system should behave in actual environment and show what could go wrong. Each use case shows the goal of the user (what user want to do) the goal of the system help to estimate the overall cost and the complexity of the entire system. How system should behave in a particular task. Use case does not show the user interface or screen and does not specify the implementation language of the system.

Each use cases are represented by using a high level use case diagram. The possible interactions between different elements that will describe in the system requirement are represented as a set of use cases. Use case diagram is a standard notation for the modeling of real word objects and system use case are employed in UML (unified modeling language). Each use case is a sequence of simple step that start with a user’s objective and end when that objective is achieved.

For example use case in a patient information system would include entities such as

·        Register patient

·        View personal info

·        View record

·        Edit record

·        Setup consultation

Each use case diagram has a following element to represent different entities in the system.  These elements are actor in the process may be a human or other system that performs a particular task. Actor can be represented as stick figure. Each class of interaction is represented as ellipse. Lines are used to link actor and classes. Arrow ahead is added to lines to show the initiation of interaction. The boundary is used to define the system of interest according to the world around it. In use case relationship between and among the actor and the use cases is shown. Too much information in to a use case diagram makes this useful technique almost useless.

Each use case should be documented with a textual description. It can help in to link other models in the UML that will develop the scenario in more detail. Use case help in requirement gathering from stakeholder who interact with the system b/c it show interaction with the system.

Use case diagram:-

Online shopping system includes element view item, make purchase, checkout, client register.

 Online shopping