Talk by Bruno Lowagie at the iText Summit in2012

1. The XML Forms Architecture
Bruno Lowagie

2. PDF: the rationale
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Portable: platform independent
Document: rendered in a reliable way
Format: page based approach
Consistent: predictable result
Fast: no programming language
Complete and compact
“Creating PDF is a One-Way Process”

3. XML Forms Architecture
• Document defined in XML
– Template: appearance of the form
– Datasets: data and data description
– Rendered on-the-fly in the viewer
• The Portable Document Format is used:
– as the container of the XML stream
– for the backgrounds of the form
“Data-based dynamical document”

4. PDF versus XFA
Pro
Contra
• XML based
• XML based
– You can use your own schema
– Easy to extract/exchange data
• Dynamic document
– Data shapes document
– Variable number of pages
• Functionality (vs AcroForm)
– More flexibility
– More feature rich
– Slow rendering for large docs
– XML manipulation
• Slow adoption by viewers
– Adobe Reader
– Preview
• Not many tools available
– Adobe LiveCycle
– Merging, splitting,...
– Problem: continuity?

5. Let’s build an XFA2PDF tool
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iText 5+: filling out XFA forms
iText 5.2.1+: making XFA forms Read-Only
XFA Worker: flatten a filled out XFA form
This is a huge work
– Time + $$$
– Specialists needed
• Different approach
– Closed source
– Customers only
– Different subprojects

6. Let’s start with XML
• Extensible Markup Language (XML) is a
set of rules for encoding documents in
machine-readable form.
• Hundreds of XML-based languages have
been developed, including RSS, Atom,
SOAP, SVG, XHTML,...

7. Converting XML to PDF
• Either you use XSLT to transform one type
of XML to another one that can be parsed
to PDF (this is what is done with XSL-FO).
• Or you can program custom parsers for
your custom XML.
• Which approach is best depends on the
project.

8. iText before XML Worker
• XmlParser with a custom iText DTD.
– Why invent a new standard?
• XmlPeer classes for custom tags.
– Good idea, but nobody understood how it works
• Writing your own DocumentHandler.
– Not for the faint of heart
• Using HTMLWorker.
– Organically grown functionality; dito frustration
• These are things of the past!

9. Understanding XML Worker
• Different pipelines
• In the case of XHTML:
CSS
pipeline
HTML
pipeline
• In the case of custom XML:
Custom
pipeline
PDF
pipeline
PDF
pipeline

10. Live Demo
PARSING XML WITH ITEXT

11. Live Demo
COMBINING XML WORKER WITH
ACROFORM TECHNOLOGY

12. Creating an XFA form

13. Importing an XSD

14. Reorganizing the fields

15. An empty form

16. A filled out form

17. Live Demo
FILLING OUT XFA FORMS

18. Try it
yourself!
Useful links:
http://demo.itextsupport.com/
xfademo/
http://www.youtube.com/
watch?v=qxtAy2Czsh0