Use Case Diagram is a diagram that shows the functionality of a system or class and how the system interacts with the outside world and describes the system functional user visible . Usually made at the beginning of development . Use case diagrams describe the expected functionality of a system . The emphasis is on " what " is done for the system , and not the " how " . A use case represents an interaction between the actors in the system . Use case is a specific job , such as logging into the system , clicking -create a shopping list , and so on . A / an actor is a human or a machine entity that interacts with the system to perform certain tasks . Use case diagrams can be very helpful when we are putting together a system of requirements , design communicate with clients , and designing test cases for all the features that exist on the system . A use case can either include another use case functionality as part of a process in itself . It is generally assumed that the use case will be invoked every time include use cases include the clicking - executed normally . A use case can be include by more than one other use case , so that duplication of functionality can be avoided by pulling out the common functionality . A use case can also be extended another use case with its own behavior . While the relationship between use case generalization shows that one use case is a specialization of the other .
Use case diagram is a graphical depiction of some or all of the actors , use cases , and the interactions between these components are introducing a system to be built . Use case diagrams describe 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 diagrams can be used during the analysis process to capture system requirements and to understand how the system is supposed to work . During the design phase , use case diagrams serve to define the behavior ( behavior) when the system is implemented . In a model there may be one or more use case diagrams . Needs or requirements the system is what functionality should be provided by the system were documented in the use case model that describes the expected system functionality ( use cases) , and that surrounding (actor ) , as well as the relationship between the actor and the use case ( use case diagram ) itself .
Components of the use case :
1. Actor
A actor is a human or a machine entity that interacts with the system to perform certain tasks.
2. Case
Description describes the actors involved.
3. Extend
Relationships are used if the use case is a use case is similar to another.
4. include
Relation if there is a behavior that is similar to a use case.
Relations in the Use Case
There are some relationships that are in use case diagram:
1. Association, the connecting link between the elements.
2. Generalization, also called inheritance (inheritance), an element can be a specialization of another element.
3. Dependency, an element depends in some way to every other element.
4. Aggregation, Association forms in which an element contains other elements.
Types of relationships / stereotypes that may occur in the Use Case diagram:
1. << include >>, ie behavior that must be met so that an event can occur, where the condition is a use case is part of another use case.
2. << extends >>, behavior that runs only under certain conditions such as moving the alarm.
3.<< Communicates >>, may be added to the association that showed association was Communicates association. This is the association of choice for the type of relationship that allowed only between actor and use case.
Benefits Use Case Model :
• Used to communicate with end users and domain experts
• Provide buy-in at the early stages of system development.
• Ensure proper understanding of the requirements / needs of the system.
• Used to identify
• Anyone who interacts with the system and what the system should do.
• Interface a must-have system.
• Used to ferifikasi
• All the requirements that have been captured.
• The development team to understand the requirements.
A blog is an internet media providing a personal note that can be seen all the local and international community, and become a medium to share the information with ease and gratis.Sebuah blog is a personal diary. Your pulpit every day. Political soapbox. Recent news outlets. Link farms. Your own private thoughts. Notes to the world.
example, Usecase on the blog :
In the blog there are 3 entities are users, visitors, and admin gmail.
Users can perform some activity on the blog, which can be memenage profile, manage post, manage category and manage comments. While visitors can only manage coment, view user profiles, and view posts.
In the manage profile, the user can input the new profiles and edit profile. In managing the post, the user can input new post, edit post and removing the previous post. Manage in the category, the user can add a category, change and delete category. While managing comment, the user can enter comments, deleting comments and changing the previous comments.
However, before carrying out the above activities as well as visitor user must be logged in and have admin approval gmail, passaword and email is entered in compliance or not. If it does not fit the user and the visitor can not carry out the above activities.
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