XML 102

1
XML 102

• Mike Rawlins
• Rawlins EC Consulting

2
Acknowledgements

• NCHELP Summer Institute organizers
• Post Secondary Electronic Standards Council
• Members of PESC XML Forum

3
Topics

• General issues questions
• Bruce gave good introduction to XML
• What else do you want to know?
• Soup to nuts illustration of key technologies
• Data analysis
• Document and Schema design
• XSLT transformations

4
Focus Interchange Format

• Goal - link systems electronically, but insulate
  them from each other, loosely coupled
• XML assists in creation of neutral interchange
  formats

5
Why XML?

• Good
• Fast
• Cheap

6
What does it?

• Programmer readable format
• Free, standard code libraries
• DOM - W3C Document Object Model
• SAX - Simple API for XML
• XSLT
• Standard language for transformations
• Free and low cost tools

7
Soup to Nuts

• Data content based on X12 TS 190
• Based on XML Forum approach
• Instance document representation
• W3C Schema
• XSLT transform to HTML for Display
• XSLT transform to XML for application
• Loading into a business application

8
Example X12 190 Trans. Set

• Student Enrollment Verification Response - School
  to National Student Loan Clearinghouse
• Header data
• Date, time, references
• Enrollment information
• Sender - school
• Receiver - clearinghouse

9
Example - TS 190, continued

• Student
• Name, ID, birth date, address
• School
• Name, FICE number

10
Document Design Issues

• A sample only!
• Naming conventions
• Semantically significant!
• Abbreviations case
• What language?
• Elements only or Attributes too?

11
Document Design Issues

• ltIDNum typeSSNgt123456789
• ltIDNumgt
• OR
• ltIDNumgt
• ltTypegtSSNltTypegt
• ltValuegt123456789ltValuegt
• ltIDNumgt

12
DISCLAIMER!!!

• These are example documents to be used only for
  illustration of approach and technique. They do
  not represent XML Forum standards or work in
  progress.
• In other words, this is all just Mikes stuff!

13
Instance Document

• StudentEnrollmentVerificationResponse.XML
• Disclaimer - Neither PESC nor the XML Forum
  endorse any particular XML product. XML Spy just
  happens to be the one that Mike likes and has
  licensed.

14
Instance Document Features

• Based on XML Forum Combined Data Dictionary 2.0
• Only uses elements
• Minimal namespace prefixes
• Date handling different from X12
• Boolean instead of Yes/No
• Uses several code lists from X12

15
Schema Document Features

• Modular structure
• Uses two namespaces (PESC XML will probably use
  several)
• Extensive use of types
• No global elements
• Code validation, lengths, cardinality

16
Why XSLT for HTML?

• One document, many uses
• Separate presentation from content
• Good software engineering, reinforces modularity

17
XLST Basics

• XPath expressions
• Walk the tree
• Similar to UNIX directory paths
• Template matches path expression
• xslvalue-of inserts node value
• xslapply-templates invokes another template at
  current context

18
XSLT for HTML Output

• xsloutput methodhtml
• Insert HTML code into a template
• Values to be displayed as value-of
• Stylesheet reference in instance XML
• Version and tool incompatibilities
• Beware of IE5!
• IE6 and Netscape6 OK

19
Why XSLT for XML to XML?

• There isnt going be just ONE XML language!
• Transformation will be our salvation!

20
XSLT for XML Output

• xsloutput methodxml
• Insert XML markup for target document
• Element and attribute values with value-of
• Namespace considerations
• Declare result namespaces
• exclude-result-prefixes

21
Loading into an application

• Native XML - XSLT transform to desired format
• Non-XML expected
• XSLT - can do but may not be best way
• Program - custom or generalized program for XML
  lt-gt non-XML
• Comma separated values
• Flat files
• EDI

22
Summary

• Data and business process analysis is the same,
  regardless of technology
• XML Schema enables validation
• XSLT performs transformation
• HTML for display
• Application import/export

23
Recommended Resources

• XML Forum Technical Specification
• www.pescxml.org
• World Wide Web Consortium
• At www.w3c.org
• XML Schema Recommendation
• XSLT Recommendation
• Tools
• XML Spy - Altova - Win32 only
• TurboXML - TIBCO - All Java platforms

24
Books

• XSLT 2nd Edition - Michael Kay, Wrox
• Essential XML Quick Reference - Skonnard
  Gudgin, AW developmentor
• Using XML with Legacy Business Applications -
  Mike Rawlins, Addison Wesley (late 2002)