Describe the following with suitable examples: A) Modeling the realization of a Use case B) Modeling the realization of an operation C) Modeling a Mechanism

A) Modeling the realization of a Use case :- A relationship is a general term covering the specific types of logical connections found on class and object diagrams. UML shows the following relationships: In UML modeling, a realization relationship is a relationship between two model elements, in which one model element (the client) realizes (implements or executes) the behavior that the other model element (the supplier) specifies. A realization is indicated by a dashed line with a unfilled arrowhead towards the supplier. Realizations can only be shown on class or component diagrams. A realization is a relationship between classes, interfaces, components, and packages that connects a client element with a supplier element. A realization relationship between classes and interfaces and between components and interfaces shows that the class realizes the operations offered by the interface.

B) Modeling the realization of an operation :- The class diagram is the main building block in object oriented modelling. It is used both for general conceptual modelling of the systematics of the application, and for detailed modelling translating the models into programming code. The classes in a class diagram represent both the main objects and or interactions in the application and the objects to be programmed. In the class diagram these classes are represented with boxes which contain three parts:

A class with three sections.

· The upper part holds the name of the class

· The middle part contains the attributes of the class

· The bottom part gives the methods or operations the class can take or undertake

In the system design of a system, a number of classes are identified and grouped together in a class diagram which helps to determine the statical relations between those objects. With detailed modeling, the classes of the conceptual design are often split in a number of subclasses. In order to further describe the behavior of systems, these class diagrams can be complemented by state diagram or UML state machine. Also instead of class diagrams Object role modeling can be used if you just want to model the classes and their relationships.

C) Modeling a Mechanism :- It is important to distinguish between the UML model and the set of diagrams of a system. A diagram is a partial graphic representation of a system's model. The model also contains documentation that drive the model elements and diagrams (such as written use cases). UML diagrams represent two different views of a system model:

· Static (or structural) view: emphasizes the static structure of the system using objects, attributes, operations and relationships. The structural view includes class diagrams and composite structure diagrams.

· Dynamic (or behavioral) view: emphasizes the dynamic behavior of the system by showing collaborations among objects and changes to the internal states of objects. This view includes sequence diagrams, activity diagrams and state machine diagrams.

UML models can be exchanged among UML tools by using the XMI interchange format.