Common Mechanisms of UML

Advanced Relationships 

Advanced Relationships can be categorized as:

• Dependency 
• Generalization 
• Association 
• Realization

Dependency 

• Specifying a change in the specification of one thing may affect another thing, but not necessarily the reverse 
• Graphically rendered as a dashed line 
• There are eight stereotypes that apply to dependency relationships among classes and objects in class diagrams 

bind	The source instantiates the target template
derive	The source may be computed from target
friend	The source is given special visibility into target
instanceOf	Source object is an instance of the target classifier
instantiate	Source object creates instance of the target
powertype	Target is a powertype of the source
refine	Source is at a finer degree of abstraction than target
use	The semantics of the source element depends on the semantics of the public part of the target

Two stereotypes that apply to dependency relationships among packages 

• Access - Source package is granted the right to reference the elements of the target package 
• Import - A kind of access, but only public content 

Two stereotypes that apply to dependency relationships among use case 

• Extend - Target use case extends the behavior of source 
• Include - Source use case explicitly incorporates the behavior of another use case at a location specified by the source 

Three stereotypes when modeling interactions among objects 

• Become - Target is the same object of source at later time 
• Call - Source operation invokes the target operation 

In the context of state machine 

• Send - Source operation sends the target event 

In the context of organizing the elements of your system into subsystem and model 

• Trace - Target is a historical ancestor of the source (model relationship among elements in different models)

Generalization 

• A generalization is a relationship between a general thing and a more specific kind of that thing 
• In multiple Inheritance one class may have more than one parent 
• Complete: Means that all children in the generalization have been indicated in the model and that no additional children are permitted 
• Incomplete: Means that all children of the generalization may not have been included and new ones can be added later 
• Disjoint: Depicts that objects of the parent do not overlap, i.e., they belong to only one child class 
• Overlapping: Indicates that objects of the parent may have more than one of the children as a type

Association 

Advanced adornments: Navigation, Qualification, Various flavors of aggregation 

Navigation: Adorning an association with an arrowhead pointing to the direction of traversal

Visibility: Objects at that end are not accessible to any objects outside the association

Qualification: This is an attribute whose values partition the set of objects related to an object across an association.

Composition: A form of an aggregation with strong ownership and coincident lifetime of the parts by the whole

Constraints: 

• Implicit: The relationship is not obvious and may be conceptual 
• Ordered: The set of objects at one end  of an association are in a piece of order
• Changeable: The links among the objects may be altered 
• AddOnly: New links may be included from an object on the opposite end of the association 
• Frozen: An existing link may not be deleted or modified 
• XOR: Over a set of relationships, exactly one is apparent for each associated object

Realization 

--A realization is a semantic relationship between classifiers in which one classifier specifies a contract that another classifier guarantees to carry out
--Used in two circumstances 

• In the context of interfaces 
• In the context of collaborations 

--Graphically rendered as dashed directed line with a large open arrowhead