1. CS 4233 Review Feb 25 2003

2. February 25 2003Review2 Outline  Previous Business – My.wpi.edu contains all grades to date for course – Review and contact TA/prof for questions  New Business – HW5 solution due tomorrow 5:00 PM

3. February 25 2003Review3 TAOO: Questions  What is the difference between links and associations?  What is the practical impact of maintaining a bidirectional association?  What is difference between aggregation and composition?  What is difference between (1) Class C extends class A; and (2) Class C uses class A as a servant class.

4. February 25 2003Review4 TAOO: Questions  How are N-ary relationships implemented? – Describe associations and links – How are core operations relevant to N-ary relationships?  How is a collection manager different from a container?  Backward Containment vs. Forward Containment

5. February 25 2003Review5 Java and OO  Polymorphism, Sub-classes  Interfaces, Sub-interfaces  Methods  Access (public, protected, private)  Static methods

6. February 25 2003Review6 Model View Controller  MVC – its variations – responsibilities assigned to M, V, and C  Use in GUIs  Precursor to EBC

7. February 25 2003Review7 Entity Boundary Controller  EBC as consolidated approach to analysis – Use cases  Control, Boundary objects – Domain Analysis  Entity objects  Describe interactions between controllers  Controllers can be abstract to represent commonalities – Specialized subclasses contain variations

8. February 25 2003Review8 EBC  All objects are not created equal – Entity  Represent persistent information required to implement desired system – Boundary  Represent interactions between actors and system – Control  Represent tasks that are performed by user and supported by system

9. February 25 2003Review9 EBC  Boundary object presented to user – Event/action takes place  Controller created (or invoked) to manage behavior  Controller may display add’l boundary  Controller manages updates to entities and boundaries

10. February 25 2003Review10 Object properties  Cohesion  Coupling  Communication with other objects  Sequence diagrams

11. February 25 2003Review11 Law of Demeter  Within a method, messages can only be sent to 1. Its enclosing object 2. A parameter of the method a.For pragmatic reasons: includes global objects 3. Attributes of the enclosing object a.Includes elements of a collection 4. An object returned by a method of the enclosing object 5. An object created within the method

12. February 25 2003Review12 Demeter Summary  Guideline for design  Many reasons for ‘breaking’ its laws – Most are pragmatic and therefore unsound  Replace micro-management with delegation

13. February 25 2003Review13 Design Patterns  Creational – Singleton Restrict access to the instance(s) of a class – Abstract Factory Provide an interface for creating families of related objects without specifying their concrete classes – Concrete Factory Consolidate all constructors in one place – Factory Method Delegate construction to subclasses

14. February 25 2003Review14 Design Patterns  Behavioral – Iterator Access elements of an aggregate object sequentially without exposing underlying representation – Visitor Define a new operation to be performed on elements of an object structure Avoid changing the classes of the elements on which the visitor operates

15. February 25 2003Review15 Design Patterns  Behavioral – Template Method Define skeleton of an algorithm, deferring steps to subclasses – Mediator Encapsulate how a set of objects interact – Command Encapsulate a request as an object