1. JSP Tag Libraries based Framework for Wireless Application Development Hitesh Kr. Seth Chief Technology Evangelist SeraNova, Inc hitesh.seth@seranova.com O’Reilly Conference on Enterprise Java, 2001

2. Agenda • Overview • Servlets • Java Server Pages • JSP Tag Libraries • Tag Libraries for Wireless Application Development • Design Requirements • Tags • Enhancements • Conclusion • References

3. Servlets

4. Servlets • Java based web server extension mechanism • Based on HTTP request-response Paradigm • Multi threaded, Session Management • Versions • J2EE v1.2 – Servlets 2.2 • J2EE v1.3 - 2.3 (Draft) • Usage Scenarios • Creating dynamic web applications • Finer control than JSP

5. Features • Extend Web Server Functionality • Similar to CGI-BIN, NSAPI/ISAPI extensions, apache Modules • Portable • Multiple Servlet implementations on various platforms • Rich • Can call any Java API, such as JDBC, EJB, JNDI etc. • High Performance • Loaded into memory once and called • Uses threads for concurrency • Can maintain connection pools

6. Features • Converts HTTP Form parameters into a Hashtable • Customizable Session Management capabilities • Using cookies and URL rewriting • Application Servers implement session management Mechanisms • Memory, File System, Relational Database; Web farm compatible • Leverage other java capabilities such as localization

7. Servlet by Example

8. Java Server Pages

9. JSP • Embedded dynamic Java scriptlets • Similar to ASP and Server Side JavaScript • Implemented as a “Self-Managed” Servlet • “Compiled” into Servlets and kept in Memory • Separates presentation from business logic • Tag Extension mechanism • Versions • J2EE v1.2 – JSP 1.1 • J2EE v1.3 – JSP 1.2 (Draft) • Usage Scenarios • Dynamic/flexible presentation layer

10. JSP Elements • Static Templates • HTML/XML/WML/... • Standard Directives • Include Directive • Page Directive • Taglib Directive • Scripting Elements • Declaration • Expression • Comments • Standard Actions • forward, get/set Property, include, plugin, useBean, param • Custom Tags • Tag Libraries

11. JSP Implicit Objects • request • response • pageContext • session • application • out • config • page • exception • Error Pages Only

12. JSP by Example

13. HTML Form (SubmitForm.jsp) JSP by Example - Interactions

14. Using Beans Without Beans JSP by Example - Beans

15. Upload HTML <form method="post" action="Upload.jsp" enctype="multipart/form-data"> <input type="file" name="FILE1" SIZE="50"><br/> <input type="submit" value="Upload"> </form> JSP Using Third Party Beans

16. JSP/Servlet Implementations • Reference Implementation • Apache Tomcat@Jakarata • Third Party Implementations • Allaire JRun Application Server • ATG Dynamo Application Server • BEA Weblogic Application Server • Gemstone/J Application Server • IBM WebSphere Application Server • iPlanet Application Server • Orion Application Server • SilverStream Application Server • etc.

17. JSP Tag Libraries

18. JSP Tag Libraries • Create application/vertical specific tags • Rich • Encapsulation of functionality • Simplified Code • Less presentation code to manage • Easier to author • Ease of Use • Ease of Use within WYSIWYG authoring tools • Portability • Reusability • Less Java “Scriptlets” • Cleaner separation of presentation format & presentation logic

19. JSP Taglib Examples • Examples • Logging <x:log message=“database #13 connection opened”/> • XSLT Transformation <xslt:transform stylesheet=“Product.xsl”>xml content </xslt:transform> • Iteration <x:Iterate …/>…</x:Iterate> • Send an Email <x:email from="hitesh.seth@seranova.com" to=“hitesh.seth@seranova.com">Message... </x:email> • JSR #000052 • A Standard Tag Library for Java Server Pages

20. Tag Libraries by Example

21. Taglib Descriptor

22. Reusable Tag Libraries • Allaire JRun Tag Library • Sql, Email, JMS, JNDI, XML Query, XSLT Transformation, Field Validation, Logic - For Each, If, Switch, Case • Apache Jakarta Taglibs • Application, BSF, DateTime, Input, JNDI, JSP Spec, Page , Regexp, Request, Response, Session, SQL, Utility, XSL • BEA Weblogic Portal Tag Library • Portal Framework • Orion Taglibs • EJB/Utility

23. Tag Libraries for Wireless Application Development

24. Design Requirements

25. Requirements Summary • Leverage existing HTTP/HTTPS based application delivery frameworks • Support multiple display formats • HTML, WML, HDML, i-mode (Compact HTML), XHTML-Basic • Simple • Similar to existing known HTML tags • Simple tags and attributes • Compliant with Authoring Tools

26. Multi-modal Page <page> Tag

27. Hello World Tag Library Multi-modal Page

28. Web Browser Wireless Microbrowser Rendering

29. Taglib Descriptor

30. Page Tag Impl. Browser Detection

31. Page Tag Impl.(contd.) WAP/WML Delivery

32. Page Tag Impl. (contd.)

33. Page Tag Impl. (contd.)

34. Hyperlinks <link> Tag

35. The Link Tag

36. HTML Browser WML Microbrowser Rendering

37. Tag Descriptor

38. Link Tag Impl.

39. Interactions <form> and <field> Tags

40. Form & Fields

41. HTML Browser Rendering

42. WML Microbrowser Rendering

43. Tag Descriptor (Field)

44. Tag Descriptor (Form)

45. Field Tag Impl. Call Parent Tag Methods

46. Form Tag Impl.

47. Form Tag Impl. Enumerate all fields

48. Taglib So far • Implemented • <page> Tag • <link> Tag • <form> Tag • <field> Tag • Common Elements • <p>, <br/>, <b>, simplified <table> • Basic Simple Constructs for creating an complete multi-modal application

49. Benefits • Similar to HTML tags • Ease of authoring/learning • Use existing XML Compliant HTML tags • <p>, <br/> etc. • Simplicity • Just <page>, <link>, <form>, <field> tags can be used to create full featured applications • Use all JSP features with the application • Session Management • Request/Response handling • Call any Java API

50. Enhancements • Implement other delivery formats • HDML, i-Mode, etc. • More functionality (more tags/attributes) • Use “body” tags • Code optimization • Use XSLT for “templated” delivery • Provide capability to implement device/network specific functionality