Mike's BLOG for CIS327

Object Diagrams

2005-03-12T21:02:00.000-08:00

A pictorial representation of the relationships between these instantiated classes at any point of time (called objects) is called an "Object diagram." It looks very similar to a class diagram, and uses the similar notations to denote relationships.

Defining a State diagram

2005-03-12T20:56:00.000-08:00

are used to help the developer better understand any complex/unusual functionalities or business flows of specialized areas of the system. In short, State diagrams depict the dynamic behavior of the entire system, or a sub-system, or even a single object in a system.

sequence diagram

2005-03-12T20:53:00.000-08:00

Is made up of objects and messages. Objects are represented exactly how they have been represented in all UML diagrams—as rectangles with the underlined class name within the rectangle.

Collaboration Diagrams

2005-03-12T20:51:00.000-08:00

A sophisticated modeling tool can easily convert a collaboration diagram into a sequence diagram and the vice versa. Hence, the elements of a Collaboration diagram are essentially the same as that of a Sequence diagram.

Use Case Diagrams

2005-03-12T20:47:00.000-08:00

is used to identify the primary elements and processes that form the system. The primary elements are termed as "actors" and the processes are called "use cases." The Use case diagram shows which actors interact with each use case.

Multiplicity

2005-03-12T20:35:00.000-08:00

Are Values which indicate how many objects of a class participate in the association.

Association

2005-03-12T20:33:00.000-08:00

An association is the relationship between classes.

encapsulation

2005-03-12T20:32:00.000-08:00

1. The technique used by layered protocols in which a layer
adds header information to the protocol data unit (PDU) from
the layer above. As an example, in Internet terminology, a
packet would contain a header from the physical layer,
followed by a header from the network layer (IP), followed by
a header from the transport layer (TCP), followed by the
application protocol data.

2. The ability to provide users with a well-defined interface
to a set of functions in a way which hides their internal
workings. In object-oriented programming, the technique of
keeping together data structures and the methods (procedures)
which act on them.

(1998-09-07)

polymorphism

2005-03-12T20:31:00.000-08:00

A concept first identified by
Christopher Strachey (1967) and developed by Hindley and
Milner, allowing types such as list of anything. E.g. in
Haskell:

length :: [a] -> Int

is a function which operates on a list of objects of any type,
a (a is a type variable). This is known as parametric
polymorphism. Polymorphic typing allows strong type checking
as well as generic functions. ML in 1976 was the first
language with polymorphic typing.

Ad-hoc polymorphism (better described as overloading) is the
ability to use the same syntax for objects of different types,
e.g. "+" for addition of reals and integers or "-" for unary
negation or diadic subtraction. Parametric polymorphism
allows the same object code for a function to handle arguments
of many types but overloading only reuses syntax and requires
different code to handle different types.

See also generic type variable.

In object-oriented programming, the term is used to describe
a variable that may refer to objects whose class is not
known at compile time and which respond at run time
according to the actual class of the object to which they
refer.

(2002-08-08)

inheritance

2005-03-12T20:20:00.000-08:00

In object-oriented
programming, the ability to derive new classes from
existing classes. A derived class (or "subclass") inherits
the instance variables and methods of the "base class"
(or "superclass"), and may add new instance variables and
methods. New methods may be defined with the same names as
those in the base class, in which case they override the
original one.

For example, bytes might belong to the class of integers for
which an add method might be defined. The byte class would
inherit the add method from the integer class.

See also Liskov substitution principle, multiple
inheritance.

(2000-10-10)

Define

2005-01-25T17:56:00.000-08:00

1. Abstraction
2. Inhertiance
3. Polymorphism
4. Encapsulation
5. Association
6. Multiplicity
7. Qualified Association
8. Reflexive Association
9. Inheritance & Generalization
10. Aggregations
11. Composites
12. Contexts
13. Interfaces and Realizations
14. Use Case Diagrams
15. Class Diagrams
16. Object Diagrams
17. State Diagrams
18. Sequence Diagrams
19. Acitivity Diagrams
20. Collaboration Diagrams
21. Component Diagrams
22. Deployment Diagrams

Abstraction

2005-01-25T17:45:00.000-08:00

Enables us to view digital images of people, animals, plants, cars, planes, trees and mountains as objects, rather than as individual dots of color. Another example would be viewing a beach instead of grains of sand.