UseCase Diagram

USE CASE

Use-case is model uml diagram used to illustrate requirement functional s expected a system. Use-case diagram stressing “ who “ ,” do what “ in the environment system software be built. Use-case diagram actually consists of two parts large; the first is use case diagram ( including picture use case dependencies ) and use case description. Use-case diagram can be used over process analysis to catch requirement system and to understand how a system should work. During the design, use-case diagram role to establish behavior ( behavior ) system when implemented. In a model there may be one or several use-case diagram. Necessity or requirements system is functionality what must be provided by the system and documented on the model use-case describing system functions expected ( use-case ) and ( actor ), that surrounds it and relations between actor with use-case ( use-case diagram ) itself.

Characteristic:

 use cases is interaction or dialogue between system and actor, including exchange messages and act done by the system.

use cases initiated by actor and probably involving the role actor other. Use cases must provide minimum value to one actor.

use cases can have anescalating defining special act of interactions or use case more could be inserted.

use case class having object use case called scenarios. Scenario said the order message and action single.

Use case Diagram consists of several components:

ACTOR

actor is representative of outsiders, process or thing that interact with the system; nor the class. Every actor participate with one or more use-case. Actor participating by use-case to exchange messages. Basically actor is not part of the diagram, use case but to be both an use case diagram needed some actor. The actor presented someone or something ( as devices other system ) that interact with the system. An actor input on may only give information system only receives information from both receive, or system and giving information on the system. Actor use case, only interact with but not having control over use case.. Actor can be described in general, or specific where we can use to differentiate relationship.

USES CASE

Use-case is system that acknowledges things are supposed to do by the system. Use-case useful to describe a behavior of a system without revealing the internal structure of the system. Use case is a specific occupation, e.g. logins to system; create a shopping lists, etc. Use case is a description functionality of a system, so that customer or users system understand and understand about the system to be constructed. Note: use case diagram is a depiction system from points of view the system users ( user ), so making use case focused more on functionality existing in system, not based on a groove or the sequence of events.

A decisive manner of use case in a system:

pattern of behavior application software.

 a description of the task of an actor.

system or  thisstuff  that gives something of value to actor.

D. that which is wrought by a software ( * not how to do it ).

RELATIONSHIP

Relatioship useful to describe the relationship between actor and use- case in the system.

Association

Serves as a communication between actor with use case are participating.

EXTERNAL

Serves to add the behavior additional into use case of association not know anything about it.

Use case Generalization

Describing relations between use case common with use case that is more specific who inherits and add a feature on it.

INCLUDE

This is the addition of deed of additional into use case basic explicitly explain addition.

Diagram use case useful in three things:

explain existing facilities ( requirements ). Use case new always makes new facility when system in analysis, and designs into focus.

 communication with clients. The use of notation and symbols in the diagram use case make developer easier communicate with klienkliennya.

make test of cases in general. Assemblage of events to use case jempatan test case worthy to events.

Any use case must be described in the document called of the documents flow of event. This document define what to do by the system when actor turn use case. Structure of documents use case thiscould variously, but generally description this the least should containing

brief description ( brief description )

actor involved

precondition that matter to use case to start

description detailed of the scene that includes play flow of it all could detail more be sub-division flow and an alternative flow.

Post condition who explains state of a system of after use case over.

Here is how to draw use-case diagram:

should make use-case diagrams, prefixed to make fdd first. It is just to help identify these processes in the system.

started by enrolling actor that deals with use-case, either as sender and receiver.

component in use-case diagram is the name use-case, description use-case and actors who participates and its role.

find dependency that demos a semantic relation between two use-case. If use-case  a  changed can result in use-case  will change anyway.

There are two sorts of dependency what deserves consideration is include and extend.

Dependency include: a use-case can include functionality use-case other as part of process in her. In general assumed that use-case included every time use-case include who executed normally. A use-case can included by more than one use-case other, so duplication functionality avoidable by means draw out functionality that common.