Chapter 8 - Web Application System Design

1. Chapter 8 - Web Application System Design • Modeling Web Application using UML • Application Server • Web Application Design

2. Modeling Web Application using UML

3. 8.1 - Modeling Web Application using UML • Modeling Web Pages • Modeling EJB

4. Modeling Web Pages • For web pages, the stereotypes indicate that the class is an abstraction of the logical behavior of a web page on either theclient or the server. The two abstractions are related to each other with a directional relationship between the two. Thisassociation is stereotyped as «build», since it can be said that a server page builds a client page .

5. Modeling Web Pages

6. Modeling Web Pages

7. Modeling Web Pages

8. Modeling Web Pages

9. Modeling Web Pages

10. Modeling EJB • Modeling EJB as a subsystem • Two approach: • Standard UML-Java Mapping • Sun JSR-000026 UML/EJB Mapping

11. Modeling EJB as a subsystem

12. Modeling EJB as a subsystem ICustomerMgt  => CustomerHome (home interface)  Icustomer    => Customer (remote interface) <<subsystem proxy>>Customer   =>CustomerEJB (bean class) validateCustomer() => findUser() (in home interface)

13. Modeling EJB as a subsystem

14. Modeling EJB as a subsystem

15. Modeling EJB as a subsystem

16. Modeling EJB as a subsystem

17. Standard UML-Java Mapping

18. Sun JSR-000026 UML/EJB Mapping

19. Application Server

20. 8.2 - Application Server • Application Servers • J2EE Application Servers • Web Server and Application Server

21. mainframe terminals terminals Application Servers • In the beginning, there was darkness and cold. Then, … Centralized, non-distributed

22. Application Servers • The In the 90' s, systems should be client- server

23. Application Servers • Today, enterprise applications use the multi-tier model

24. Application Servers • " The Multi- tier applications" have several independent components • An application server provides the infrastructure and services to run such applications

25. Application Servers • Application server products can be separated into 3 categories: • J2EE-based solutions • Non-J2EE solutions (PHP, ColdFusion, Perl, etc.) • And the Microsoft solution (ASP/COM and now .NET with ASP.NET, VB.NET, C#, etc.)

26. J2EE Application Servers • Major J2EE products: • BEA WebLogic • IBM WebSphere • Sun iPlanet Application Server • Oracle 9iAS • HP/Bluestone Total-e-Server • Borland AppServer • Jboss (free open source)

27. Web Server and Application Server App Server 1 Internet Browser Web Server(HTTP Server) HTTP(S) App Server 2

28. Web Application Design

29. 8.3 - Web Application Design • Application Layer • Business Layer • J2EE Multi-tier Model • J2EE Application Scenarios • Main Technologies • Examples • Case Study –Online Bank

30. Application Layer

31. Business Layer

32. J2EE Multi-tier Model

33. J2EE Application Scenarios • Multi-tier typical application

34. J2EE Application Scenarios • Stand-alone client

35. J2EE Application Scenarios • Web-centric application

36. J2EE Application Scenarios • Business-to-business

37. Main technologies • JavaServer Pages (JSP) • Servlet • Enterprise JavaBeans (EJB) • JSPs, servlets and EJBs are application components

38. JSP • Used for web pages with dynamic content • Processes HTTP requests (non-blocking call-and-return) • Accepts HTML tags, special JSP tags, and scriptlets of Java code • Separates static content from presentation logic • Can be created by web designer using HTML tools

39. Servlet • Used for web pages with dynamic content • Processes HTTP requests (non-blocking call-and-return) • Written in Java; uses print statements to render HTML • Loaded into memory once and then called many times • Provides APIs for session management

40. EJB • EJBs are distributed components used to implement business logic (no UI) • Developer concentrates on business logic • Availability, scalability, security, interoperability and integrability handled by the J2EE server • Client of EJBs can be JSPs, servlets, other EJBs and external aplications • Clients see interfaces

41. EJB – The Big Picture

42. EJB at runtime Client can be local or remote

43. EJB at runtime

44. Types of EJB

45. Session Bean • Stateful session bean: • Retains conversational state (data) on behalf of an individual client • If state changed during this invocation, the same state will be available upon the following invocation • Example: shopping cart

46. Session Bean • Stateless session bean: • Contains no user-specific data • Business process that provides a generic service • Container can pool stateless beans • Example: shopping catalog

47. Entity Bean • Represents business data stored in a database ? persistent object • Underlying data is normally one row of a table • A primary key uniquely identifies each bean instance • Allows shared access from multiple clients • The Can live past the duration of client' s session • Example: shopping order

48. Entity Bean • Bean-managed persistence (BMP): bean developer writes JDBC code to access the database; allows better control for the developer • Container-managed persistence (CMP): container generates all JDBC code to access the database; developer has less code to write, but also less control

49. Message-Driven Bean • Message consumer for a JMS queue or topic • Benefits from EJB container services that are not available to standard JMS consumers • Has no home or remote interface • Example: Order processing – stock info

50. Examples • JSP example • Servlet example • EJB example