27-07-2012, 03:29 PM
UML description
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UML is popular for its diagrammatic notations. We all know that UML is for visualizing, specifying, constructing and documenting the components of software and non software systems. Here theVisualization is the most important part which needs to be understood and remembered by heart.
UML notations are the most important elements in modeling. Efficient and appropriate use of notations is very important for making a complete and meaningful model. The model is useless unless its purpose is depicted properly.
So learning notations should be emphasized from the very beginning. Different notations are available for things and relationships. And the UML diagrams are made using the notations of things and relationships. Extensibility is another important feature which makes UML more powerful and flexible.
The chapter describes the UML Basic Notations in more details. This is just an extension to the UML buildling block section I have discussed in previous chapter.
Structural Things:
Graphical notations used in structural things are the most widely used in UML. These are considered as the nouns of UML models. Following are the list of structural things.
• Classes
• Interface
• Collaboration
• Use case
• Active classes
• Components
• Nodes
Class Notation:
UML class is represented by the diagram shown below. The diagram is divided into four parts.
• The top section is used to name the class.
• The second one is used to show the attributes of the class.
• The third section is used to describe the operations performed by the class.
• The fourth section is optional to show any additional components.
State machine Notation:
State machine describes the different states of a component in its life cycle. The notations are described in the following diagram.
Association Notation:
Association describes how the elements in an UML diagram are associated. In simple word it describes how many elements are taking part in an interaction.
Association is represented by a dotted line with (without) arrows on both sides. The two ends represent two associated elements as shown below. The multiplicity is also mentioned at the ends (1, * etc) to show how many objects are associated.