UML - Unified Modeling Language

UML has two types of diagrams - 

1. Structure diagrams - defines the static structures of the design - Class diagram 
2. Behavior diagrams - defines the activities of the design - Sequence diagram, activity diagram, use case diagram.

1. UML Class diagram structures - A structure diagram

Conceptual model - Helps to understand the entities and the interaction between them.

You must know the following structures before you claim that you know UML class diagrams!!!

1. UML building blocks
2. Rules to connect the building blocks
3. Common mechanism of UML

+ - Public access specified in class diagram.

# - Protected access specified in class diagram.

- - Private access specified in class diagram.

In class diagram the abstract class is defined by writing the class name in italic.

Implementing an Interface is called as Realization in UML class diagram. i.e Car realizes a Vehicle behavior. 

Default value to an attribute in a class

Represent Static method or attribute in a class

      To represent static method or attribute in a class diagram underline the specific method or attribute in the class diagram.

References:

http://www.ibm.com/developerworks/rational/library/content/RationalEdge/sep04/bell/

http://www.uml-diagrams.org/class.html

http://www.sparxsystems.com/resources/uml2_tutorial/uml2_classdiagram.html

2. UML Sequence diagram structures - a kind of Interaction Diagram

Message can be of two types

• Synchronous - Represented by solid arrow mark 

• Asynchronous - Represented by stick arrow head

References:

http://www.ibm.com/developerworks/rational/library/3101.html