Lecture 3: Relationships and Packages Flashcards
What is a relationship?
A relationship is a connection between modelling elements
What does association have between classes?
- Aggregation
- Composition
- Association classes
What is a link?
- Is the connection between objects
* How they communicate using messages to invoke operations
What is the term used to implement links in OO programming?
Object references/Pointers
What is an association?
- Relationships between classes
* Links Instantiate association
What is multiplicity?
Is a constraint that specifies the number of objects that can participate in a relationship
What is a reflexive association?
- Is a relationship that “reflexes” itself.
* Objects of the class have links to other objects of the same class
What is navigability?
• Traverse an object SOURCE CLASS into a TARGET CLASS
What is the standard practice of navigability?
- Bi-directional associations have NO arrows
- Unidirectional associations have a SINGLE arrow
- Can’t show association that are navigable in BOTH directions
When do we use association?
- The target class is important part of the model
* Target class shown in the model
When do we use attributes?
- When it is not the important part of the domain (number/string)
- Just an implementation
What is a association class syntax?
The association class consists of the class, the association and the dashed line
What two important links does association class syntax consist of?
They are links that have attributes and operations
When can you use association classes?
When there is only ONE UNIQUE LINK between objects
What is generalisation?
A relationship between a common class that shares the same attributes and behaviour in a generalised class
What is class inheritance
When a child class inherits all the features from the parent class
What is overriding?
Subclasses override the methods of superclasses with the same signatures constraints and relationships
What is an abstract class?
• A class that does not provide a complete declaration cannot be instantiated.
What is Polymorphism?
- Has many forms of and changes of implementation.
* It allows you to design systems to use as an abstract class then substitute concrete classes
What is analysis packages?
• Organises modelling elements into groups
o Defines the semantic boundary
o Provides parallel working and configuration
What do analysis packages contain?
Classes, data. entities, use cases and analysis packages
What is the UML term for analysis packages?
Logical grouping mechanism
What is Package generalisation?
- More child packages inherit the public and private operations of the parent
- Child packages override the parent package
What is Architectural Analysis?
Organises the groupings of model elements that have a strong semantic connection into cohesive packages
- Should be layered and partitioned
- Coupling packages should be minimised
How do you find analysis packages?
• Discovered in model matures
• Natural groupings in use case model to identify the analysis packages
- One or more business process/actors
What does the architectural analysis define?
The structure of the analysis model defines the logical system architecture
