1. Components Lecture Five

2. Group Projects • Draft material due on Feb. 18 • Assignment Description due on Feb. 18 • URLs for group work • Sign up for review • Final material due on March 1st.

3. Reading after Class • Szyperski • Chapters 1, 4, 5, 7, 8, 9, 10, 15

4. Elements for Designing Good Software Components

5. Elements

6. Components

7. Component Characteristics

8. Object Characteristics

9. Components and Architecture

10. Component

11. Component Technologies

12. From Classes/Objects to Components

13. Interfaces

14. Ways of Providing Interfaces

15. Contracts

16. Contracts and Callback

17. JavaBeans Architecture

18. JavaBeans Architecture

19. Integrating JavaBeans

20. A Simple Bean

21. Serialization

22. Introspection

23. Event Dispatching

24. Events

25. Example

26. Example

27. Event Listeners

28. Example

29. Design Pattern for Event Listerners

30. Event Source

31. Example

32. Example

33. Example

34. Adapters

35. Example

36. Relation to JavaBeans

37. JavaBeans and Enterprise JavaBeans

38. Application Architecture • Macro-level physical and logical system structure • partition code into packages • Distributing packages and processes among network nodes • Collaboration strategies

39. Partition • Layers: vertical partitions • Subsystems: horizontal partitions • Example: • Viewer Layer • Application Layer • Domain Layer • Persistence Layer

40. Couplings • Strongly/weak coupled • Reduce couplings between layers is primarily done by introducing an interface (façade) • Reduce couplings between subsystems is done by introducing components

41. Two Java Component Architectures • JavaBeans Architecture • Use Observer pattern • Invisible/visible • Enterprise JavaBeans Architecture • distributing components on a network • Locating, instantiating, communicating with these distributed components • Session/Entity Beans

42. Enterprise Java Server • Has EJB contains • Containers manage life-cycle of EJB • Locate/instantiate/transaction/…

43. View • All user interface classes • Only layer visible to actors • Undergo most changes • Less reuable, rarely subclassed • Instatiate classes from Application model layer • Propagate events to app. Model layer

44. Appliation Model Layer • Mediate between View Layer and Domain Layer • Most Application Logic • Controllers • View controllers (application logic only, no business logic): JavaBeans • Use case controllers (transactional): Session Beans • Adapters

45. Domain • Business objects • Reusable to all applicatons • Comprehenible to everyone • Most persistent: Ivisible JavaBeans • Coupled to persistence layer only

46. Persistence Layer • Weakly coupled to Domain Layer (preferably by metadata)

47. Layer Distribution • Fat Client • All application layers on client; server nodes for persistent storage • Not scalable • Anorexic • Web browser only; 3270 client • Limited functionality

48. Layer Distribution (II) • Big-boned Client • Viewer layer and part of application-model layer on client • Viewer controllers on client; user case controller on upper tier • Domain objects travel back and froth between client and server • Shared resources on server; rich interface; client software installation required