Sequence Diagram
A sequence diagram displays object interactions arranged in a time sequence
Collaboration Diagram
A collaboration diagram displays object interactions organized around objects and their links to one another
Class Diagrams
A class diagram shows the existence of classes and their relationships in the logical view of a system
UML modeling elements in class diagrams
– Classes and their structure and behavior
– Association, aggregation, dependency, and inheritance relationships
– Multiplicity and navigation indicators
– Role names
Classes
A class is a collection of objects with common structure, common behavior, common relationships and common semantics
Classes are found by examining the objects in sequence and collaboration diagram
A class is drawn as a rectangle with three compartments
Classes should be named using the vocabulary of the domain
– Naming standards should be created
– e.g., all classes are singular nouns starting with a capital letter
Operations
The behavior of a class is represented by its operations
Operations may be found by examining interaction diagrams
Attributes
The structure of a class is represented by its attributes
Attributes may be found by examining class definitions, the problem requirements, and by applying domain knowledge
Relationships
Relationships provide a pathway for communication between objects
Sequence and/or collaboration diagrams are examined to determine what links between objects need to exist to accomplish the behavior -- if two objects need to “talk” there must be a link between them
Three types of relationships are:
– Association
– Aggregation
– Dependency
Relationships
An association is a bi-directional connection between classes
– An association is shown as a line connecting the related classes
An aggregation is a stronger form of relationship where the relationship is between a whole and its parts
– An aggregation is shown as a line connecting the related classes with a diamond next to the class representing the whole
A dependency relationship is a weaker form of relationship showing a relationship between a client and a supplier where the client does not have semantic knowledge of the supplier
– A dependency is shown as a dashed line pointing from the client to the supplier
Finding Relationships
Relationships are discovered by examining interaction diagrams
– If two objects must “talk” there must be a pathway for communication
Multiplicity and Navigation
Multiplicity defines how many objects participate in a relationships
– Multiplicity is the number of instances of one class related to ONE instance of the other class
– For each association and aggregation, there are two multiplicity decisions to make: one for each end of the relationship
Although associations and aggregations are bi-directional by default, it is often desirable to restrict navigation to one direction
– If navigation is restricted, an arrowhead is added to indicate the direction of the navigation
Inheritance
Inheritance is a relationships between a superclass and its subclasses
There are two ways to find inheritance:
– Generalization
– Specialization
Common attributes, operations, and/or relationships are shown at the highest applicable level in the hierarchy
The State of an Object
A state transition diagram shows
– The life history of a given class
– The events that cause a transition from one state to another
– The actions that result from a state change
State transition diagrams are created for objects with significant dynamic behavior
The Physical World
Component diagrams illustrate the organizations and dependencies among software components
A component may be
– A source code component
– A run time components or
– An executable component
Interfaces
The interfaces to a component may be shown on a component diagram
Deploying the System
The deployment diagram shows the configuration of run-time processing elements and the software processes living on them
The deployment diagram visualizes the distribution of components across the enterprise.
Extending the UML
Stereotypes can be used to extend the UML notational elements
Stereotypes may be used to classify and extend associations, inheritance relationships, classes, and components
Examples:
– Class stereotypes: boundary, control, entity, utility, exception
– Inheritance stereotypes: uses and extends
– Component stereotypes: subsystem
Summary
Visual modeling can be used to:
– Define business process
– Communicate
– Manage complexity
– Define software architecture
– Promote reuse
The UML is the standard language for visualizing, specifying, constructing, and documenting the artifacts of a software-intensive system
– It can be used with all processes, throughout the development life cycle, and across different implementation technologies.
