20100723 (tc design)

What's "changablility" mean in "property"?

Difference between "Extend" and "Inheritance/Generalization" in Use Case?

When to use "Dependency" in Use Case?

In sequence diagram, what's the difference between "synchronized message" and "send signal message"? And are "return messsage" used only for "asynchronized message"?

What dose the color (red/blue/green) stand for in Use Case and Sequence Diagram?

How to show annotation in UML?

Association represents the ability of one instance to send a message to another instance. This is typically implemented with a pointer or reference instance variable, although it might also be implemented as a method argument, or the creation of a local variable.

Aggregation [...] is the typical whole/part relationship. This is exactly the same as an association with the exception that instances cannot have cyclic aggregation relationships (i.e. a part cannot contain its whole).
The fact that this is aggregation means that the instances of Node cannot form a cycle. Thus, this is a Tree of Nodes not a graph of Nodes.

Composition [...] is exactly like Aggregation except that the lifetime of the 'part' is controlled by the 'whole'. This control may be direct or transitive. That is, the 'whole' may take direct responsibility for creating or destroying the 'part', or it may accept an already created part, and later pass it on to some other whole that assumes responsibility for it.

Generalization
Class diagram showing generalization between one superclass and two subclassesThe Generalization relationship indicates that one of the two related classes (the subtype) is considered to be a specialized form of the other (the super type) and supertype is considered as 'Generalization' of subtype. In practice, this means that any instance of the subtype is also an instance of the supertype. An exemplary tree of generalizations of this form is found in binomial nomenclature: human beings are a subtype of simian, which are a subtype of mammal, and so on. The relationship is most easily understood by the phrase 'A is a B' (a human is a mammal, a mammal is an animal).
The UML graphical representation of a Generalization is a hollow triangle shape on the supertype end of the line (or tree of lines) that connects it to one or more subtypes.
The generalization relationship is also known as the inheritance or "is a" relationship.
The supertype in the generalization relationship is also known as the "parent", superclass, base class, or base type.
The subtype in the specialization relationship is also known as the "child", subclass, derived class, derived type, inheriting class, or inheriting type.
Note that this relationship bears no resemblance to the biological parent/child relationship: the use of these terms is extremely common, but can be misleading.
Generalization-Specialization relationship
A is a type of B
E. g. "an oak is a type of tree", "an automobile is a type of vehicle"
Generalization can only be shown on class diagrams and on Use case diagrams.

Realization
In UML modeling, a realization relationship is a relationship between two model elements, in which one model element (the client) realizes 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.

Dependency is a weaker form of relationship which indicates that one class depends on another because it uses it at some point of time. Dependency exists if a class is a parameter variable or local variable of a method of another class.

Multiplicity
The association relationship indicates that (at least) one of the two related classes makes reference to the other. In contrast with the generalization relationship, this is most easily understood through the phrase 'A has a B' (a mother cat has kittens, kittens have a mother cat).
The UML representation of an association is a line with an optional arrowhead indicating the role of the object(s) in the relationship, and an optional notation at each end indicating the multiplicity of instances of that entity (the number of objects that participate in the association).

Subsystem or component
The system or application that you are working on, or a part of it. Can be anything from a large network to a single class in an application.
The use cases that a system or component supports appear inside its rectangle. It can be useful to show some use cases outside the rectangle, to clarify the scope of your system.

Use Case Include
An including use case calls or invokes the included one. Inclusion is used to show how a use case breaks into smaller steps. The included use case is at the arrowhead end.
Notice that the diagram does not show the order of the steps. You can use an activity diagram, sequence diagram, or other document to describe these details.
 
 
Use Case Extend
An extending use case adds goals and steps to the extended use case. The extensions operate only under certain conditions. The extended use case is at the arrowhead end.
Notice that the diagram does not show the exact circumstances under which the extension applies: you can record these in a comment or other document.

Use Case Inheritance
Relates a specialized and a generalized element. The generalized element is at the arrowhead end.
A specialized use case inherits the goals and actors of its generalization, and may add more specific goals and steps for achieving them.
A specialized actor inherits the use cases, attributes and associations of its generalization, and may add more.

Use Case Dependency
Indicates that the design of the source depends on the design of the target.