11 © Copyright 2008 IBM Corporation. XForms: The Perfect Front-End to Your Composite Application Doug Tidwell, IBM

2 © Copyright 2008 IBM Corporation. The problem We need interfaces to create, edit and update XML documents. –XML documents are at the heart of tens of thousands of Web services applications. –XML documents are at the heart of every human interaction with a business process (BPEL). –It’s easier to create XML than it is to create some other document format and then convert it to XML. We need some way to create interfaces for XML documents.

3 © Copyright 2008 IBM Corporation. Some approaches to this problem We could edit the XML by hand in emacs, vi, Notepad, or some equally unfriendly tool. –Very error-prone, particularly for complicated XML document types –Acceptable to geeks only We could write a graphical application that used various kinds of controls to edit the XML behind the scenes. –Very high cost of development –We still have to write the code to map values selected in each control to something in the XML document –Difficult to maintain as the XML document structure changes

4 © Copyright 2008 IBM Corporation. Some approaches to this problem We could write an HTML page with our favorite AJAX library. –Faster than building a graphical application, but… –We still have to write the code to map values selected in each control to something in the XML document –Difficult to maintain as the XML document structure changes We could use XForms. –Similar development time compared to AJAX –XForms has a built-in data model (unlike everything else we’ve mentioned) –Interface controls are tied directly to the XML –Much easier to maintain as the XML structure changes.

5 © Copyright 2008 IBM Corporation. The paradigm When you need to create a user interface for XML data, use XForms.

66 © Copyright 2008 IBM Corporation. Our Sample Application: Bracketology

7 © Copyright 2008 IBM Corporation. Bracketology Our XML document represents a sixteen-team, single-elimination tournament. We’ll choose between competitors until only one is left. We’ll use XForms to display the competitors, update the XML data and generate the matchups for the later rounds of the tournament.

8 © Copyright 2008 IBM Corporation. The XML document structure The Santa Clara Smackdown...

9 © Copyright 2008 IBM Corporation. A contestant <contestant seed="1" image="images/sca-sdo.jpg"> SCA-SDO The seed determines the matchups in the first round. The image attribute is used as a URL. The text of the element is what appears in the bracket.

10 © Copyright 2008 IBM Corporation. A result <result round="1" firstSeed="1" secondSeed="16" winnerSeed="1"/> The round attribute indicates in which of the four rounds this result occurred. The firstSeed and secondSeed attributes indicate which contestants faced each other. The winnerSeed attribute indicates who won. They move on to the next round.

11 © Copyright 2008 IBM Corporation. Complications The seedings of the contestants determine the matchups for the first round. We don’t know who’s involved in the second round until the first round is completed. It’s confusing. For example: –The winner of the first matchup in the first round is the first contestant in the first matchup of the second round. –The winner of the second matchup in the first round is the second contestant in the first matchup of the second round.

12 © Copyright 2008 IBM Corporation. Assembly with SCA winnerSeed="1" winnerSeed="9"... firstSeed="1" secondSeed="9" We can define these relationships in XForms. When we move from one round to the next, we’ll use to update the results correctly.

13 © Copyright 2008 IBM Corporation. Choosing between contestants

14 © Copyright 2008 IBM Corporation. XHTML page layout

15 © Copyright 2008 IBM Corporation. The bracket display

16 © Copyright 2008 IBM Corporation. Demo time Let the games begin!

17 © Copyright 2008 IBM Corporation. Summary

18 © Copyright 2008 IBM Corporation. Summary We’ve used an XForms document to display and manipulate a complicated XML document format. All of the data manipulation is done in XForms, yet we get nice AJAX-like effects as we move between rounds, panels, etc. The result is a sophisticated interface that is built around our XML document type, generates valid XML data and is easily maintained.

19 © Copyright 2008 IBM Corporation. Bracketology articles at developer Works Using XSLT to generate the bracket from the XML: –Uses new features from XSLT 2.0/XPath 2.0: The to operator, sequences and – ibm.com/developerworks/xml/library/ x-xslt20xpath20/ Use an XForms document as a custom XML editor: –Covers the entire XForms document we’ve demonstrated here –Uses XSLT 2.0 to refactor the XForms code, leaving a 70% smaller document to maintain – ibm.com/developerworks/library/x-xformsxslt/ Host your own tournament!

20 © Copyright 2008 IBM Corporation. One more time When you need to create a user interface for XML data, use XForms.

21 © Copyright 2008 IBM Corporation. oasis-opencsa.org/sca-roadshow/

22 © Copyright 2008 IBM Corporation. Thanks! Doug Tidwell, IBM