The Unified Modeling Language (UML)- part 3

Object Diagrams
An object diagram may be considered a special case of a class diagram. Object diagrams use a subset of the elements of a class diagram in order to emphasize the relationship between instances of classes at some point in time. They are useful in understanding class diagrams. They don’t show anything architecturally different to class diagrams, but reflect multiplicity and roles.

Class and Object Elements
The following diagram shows the differences in appearance between a class element and an object element. Note that the class element consists of three parts, being divided into name, attribute and operation compartments; by default, object elements don’t have compartments. The display of names is also different: object names are underlined and may show the name of the classifier from which the object is instantiated.

Run Time State
A classifier element can have any number of attributes and operations. These aren’t shown in an object instance. It is possible, however, to define an object’s run time state, showing the set values of attributes in the particular instance.

Example Class and Object Diagrams
The following diagram shows an object diagram with its defining class diagram inset, and it illustrates the way in which an object diagram may be used to test the multiplicities of assignments in class diagrams. The car class has a 1-to-many multiplicity to the wheel class, but if a 1-to-4 multiplicity had been chosen instead, that wouldn’t have allowed for the three-wheeled car shown in the object diagram.

Composite Structure Diagram

Composite Diagrams
A composite structure diagram is a diagram that shows the internal structure of a classifier, including its interaction points to other parts of the system. It shows the configuration and relationship of parts, that together, perform the behavior of the containing classifier.

Class elements have been described in great detail in the section on class diagrams. This section describes the way classes can be displayed as composite elements exposing interfaces and containing ports and parts.

A part is an element that represents a set of one or more instances which are owned by a containing classifier instance. So for example, if a diagram instance owned a set of graphical elements, then the graphical elements could be represented as parts; if it were useful to do so, to model some kind of relationship between them. Note that a part can be removed from its parent before the parent is deleted, so that the part isn’t deleted at the same time.

A part is shown as an unadorned rectangle contained within the body of a class or component element.

A port is a typed element that represents an externally visible part of a containing classifier instance. Ports define the interaction between a classifier and its environment. A port can appear on the boundary of a contained part, a class or a composite structure. A port may specify the services a classifier provides as well as the services that it requires of its environment.

A port is shown as a named rectangle on the boundary edge of its owning classifier.

An interface is similar to a class but with a number of restrictions. All interface operations are public and abstract, and do not provide any default implementation. All interface attributes must be constants. However, while a class may only inherit from a single super-class, it may implement multiple interfaces.

An interface, when standing alone in a diagram, is either shown as a class element rectangle with the «interface» keyword and with its name italicized to denote it is abstract, or it is shown as a circle.

Note that the circle notation does not show the interface operations. When interfaces are shown as being owned by classes, they are referred to as exposed interfaces. An exposed interface can be defined as either provided or required. A provided interface is an affirmation that the containing classifier supplies the operations defined by the named interface element and is defined by drawing a realization link between the class and the interface. A required interface is a statement that the classifier is able to communicate with some other classifier which provides operations defined by the named interface element and is defined by drawing a dependency link between the class and the interface.

A provided interface is shown as a “ball on a stick” attached to the edge of a classifier element. A required interface is shown as a “cup on a stick” attached to the edge of a classifier element.

A delegate connector is used for defining the internal workings of a component’s external ports and interfaces. A delegate connector is shown as an arrow with a «delegate» keyword. It connects an external contract of a component as shown by its ports to the internal realization of the behavior of the component’s part.

A collaboration defines a set of co-operating roles used collectively to illustrate a specific functionality. A collaboration should only show the roles and attributes required to accomplish its defined task or function. Isolating the primary roles is an exercise in simplifying the structure and clarifying the behavior, and also provides for re-use. A collaboration often implements a pattern.

A collaboration element is shown as an ellipse.

Role Binding
A role binding connector is drawn from a collaboration to the classifier that fulfils the role. It is shown as a dashed line with the name of the role at the classifier end.

A represents connector may be drawn from a collaboration to a classifier to show that a collaboration is used in the classifier. It is shown as a dashed line with arrowhead and the keyword «represents».

An occurrence connector may be drawn from a collaboration to a classifier to show that a collaboration represents (sic) the classifier. It is shown as a dashed line with arrowhead and the keyword «occurrence».

This tutorial is collected from following Source and use as it is:


One Response

  1. […] public links >> classifier The Unified Modeling Language (UML)- part 3 Saved by sandman2343 on Sun 14-12-2008 Design and Analysis of Learning Classifier Systems: A … […]

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