Use Case Diagram.pptx

use case diagram

1. Use Case Diagram

2. What is Use Case Diagram? Use Case Diagram  captures the system’s functionality and requirements by using actors and use cases . Use Cases model the services, tasks, function that a system needs to perform. Use cases represent high-level functionalities and how a user will handle the system. Use-cases are the core concepts of Unified Modelling language modeling.

3. Use Case Diagrams Use Case Diagrams provide a visual way to document user goals and explore possible functionality Three primary modeling components: Actors Use Cases Relationships between use cases Authorized Staff Worker Teacher Student Record class grades Review Transcripts

4. Why Use-Case Diagram? A Use Case consists of use cases, persons, or various things that are invoking the features called as actors and the elements that are responsible for implementing the use cases. Use case diagrams capture the dynamic behaviour of a live system. It models how an external entity interacts with the system to make it work. Use case diagrams are responsible for visualizing the external things that interact with the part of the system.

5. When to use a use-case diagram? In general use case diagrams are used for: Analyzing the requirements of a system High-level visual software designing Capturing the functionalities of a system Modeling the basic idea behind the system Forward and reverse engineering of a system using various test cases.

6. Use-case diagram notations Use-case: Use cases are used to represent high-level functionalities and how the user will handle the system. A use case represents a distinct functionality of a system, a component, a package, or a class. It is denoted by an oval shape with the name of a use case written inside the oval shape. The notation of a use case in UML is given below:

7. Use-case diagram notations Actor: Actors can be a human user, some internal applications, or may be some external applications The actor is an entity that interacts with the system. A user is the best example of an actor. An actor is an entity that initiates the use case from outside the scope of a use case. One actor can be associated with multiple use cases in the system. The actor notation in UML is given below.

8. How to draw a use-case diagram? Following rules must be followed while drawing use-case for any system: The name of an actor or a use case must be meaningful and relevant to the system. Interaction of an actor with the use case must be defined clearly and in an understandable way. Annotations must be used wherever they are required. If a use case or an actor has multiple relationships, then only significant interactions must be displayed.

9. Example Use Case Diagram Coming up: Use Case Diagrams

10. Relationships Between Actors Actors can be related by generalization/specialization Generalization of an actor means that one actor can inherit the role of the other actor. The descendant inherits all the use cases of the ancestor. The descendant has one or more use cases that are specific to that role

11. Use Case Relationships Includes Extends Generalization After a while you realize extends and generalization are not too different. Just know generalization and includes… forget about extends (the difference is only in intent)

12. <<Include>> Relationship In UML modeling, an include relationship is a relationship in which one use case (the base use case) includes the functionality of another use case (the inclusion use case). The include relationship supports the reuse of functionality in a use-case model. Includes Dependency : Defines how one use case can invoke behavior defined by another use case Few things to consider when using the <<include>> relationship. The base use case is incomplete without the included use case. The included use case is mandatory and not optional. .

13. <<Include>> Relationship For example – both withdraw money and deposit money use case require the customer to login The <<include>> association specifies that to accomplish the use-case withdraw money the user must login to the account

14. <<Include>> Relationship

15. <<include>> Relationships In an online retail system if Make a Purchase is a use case what could be the included use case? Make a Purchase Verify Credit Cards <<include>>

16. <<include> Relationship In an ATM system, what common use case can be included for both withdraw cash and transfer funds use case? Withdraw cash Transfer Fund Verify Balance <<include>> <<include>>

17. <<extend>> Relationships Extends dependency : defines a use-case that is a variation of another, usually for handling an abnormal situation You can add extend relationships to a model to show the following situations: A part of a use case that is optional system behavior A subflow is executed only under certain conditions A set of behavior segments that may be inserted in a base use case

18. <<extend>> Relationships

19. Use-Case Relations Generalization : Defines one use case as a generalization of another . Replaces generic functionality with alternate implementation Teacher Alter Student Grade Alter Student Grade for a Graduate Course 20 Coming up: Documenting Use Cases