Usecase Diagram

Use-case diagram is a UML diagram that models used to describe requirementfungsional expected from a system . Use-case diagram emphasizes on "who " did " what " within the software system to be built . Actual use-case diagram consists of two major parts , the first is the use case diagram ( use case dependencies including images ) and use case description .

Use-case diagram is a graphical depiction of some or all of the actors , use-case , and the interactions between these components are introducing a system to be built . Use-case diagrams to explain the benefits of a system when viewed in the eyes of people who are outside the system . This diagram shows the functionality of a system or class and how the system interacts with the outside world .

● Use case classes are used to model and express unit functions / services provided by the system (or parts of systems: subsystems or class) to the user.

● Use case can be covered with restrictions systems that are labeled name system.

● Use case is something that provides measurable results to the user or external system.

characteristics:

- Use cases are interaction or dialogue between the system and actors, including the exchange of messages and actions performed by the system.

- Use cases initiated by the actor and may involve the role of other actors. Use cases should provide a minimum value to the actor.

- Use cases can have an extension that defines specific actions in interactions or other use case may be inserted.

- Use case class has an object called a use case scenario. Scenarios expressed sequences and single action message.

Forming Component Use Case Diagram :

1 . Actor

Basically the actor is not a part of the use case diagram , but to be able to create a use case diagram needed some actor . The actors present someone or something ( such as devices , other systems ) that interact with the system . An actor may only provide information input to the system , only receive information from the system or both receiving and giving information on the system . Actors only interact with the use case , but does not have control over the use case . Actordigambarkan with a stick man . Actor can be described in general or specific , which we can use to distinguish relationship .

2 . Use Case

Use case is a description of the functionality of a system , so that the customer or system users know and understand about the usefulness of the system to be built .

Note : Use case diagram is a depiction of the system from the viewpoint of the system user ( user ) , thus making the use case is more focused on the functionality that exists on the system , not based on the flow or sequence of events .

How to determine a Use Case in the system :

a. Behavior patterns of software applications .

b . Job description of an actor .

c . Systems or " objects " which gives something of value to the actor .

d . What is done by the software ( * not how to do it ) .

 

 Sample images Interaction Between Actors and Systems (Use-case) on the blog:

 

This is an example usecase for the blog . Actors associated with the user profile usecase , usecase following other blogs , posting usecase . Usecase profile in which there are other elements such as edit profile , new profile , and delete profiles . On edit profile element , the user can change their self - change of data , such as account name , account password , account display picture . In the new profile element , the user can create a new profile you want to display on their blogs . On delete profile elements , users can delete the existing profile .

Usecase following other blogs in which there are other elements such as the following and unfollow . On the following elements , the user can follow the blog to see the latest posts from the blog . Users can participate in more than one blog . At unfollow element , the user can not follow a blog . Users can unfollow more than one blog .

Usecase posts in which there are other elements such as edit posts , new posts , and delete posts . In the post edit elements , the user can change the article that had their previous posts . At post new element , the user can post a new article on his blog . In the post delete elements , users can delete existing posts .

Admin on actors , there is a login usecase . At the login usecase there are elements of the password and username . If the username and password entered by the admin is correct, then the admin can relate to usecase profile , usecase following other blogs , posting usecase .