1. Drupal and SimpleXML

2. XML parsing
• Very well defined, well known standards
• Excellent support ...
• ... in most other languages
• Long-standing PHP weakness
(up to version 4)

3. two main models

4. SAX

5. Simple API for XML
• Stream - based xml parsing
• Event - driven API
• Uni-directional

6. DOM

7. Document Object Model
• Full object representation of an XML
document
• Supports writing documents
• Same system used by browsers, javascript,
etc (i.e. “known quantity”)

8. Other key concepts
• Namespaces: Allow extending existing XML
documents
• XPath: selector syntax for addressing parts
of a document
• XSLT: “template” language for transforming
XML documents into other formats

9. DOM in PHP
• http://php.net/domxml
• Traditionally required external libraries and
additional PHP compile flags
• Has been removed from PHP core in PHP5
(available as a PECL module)
• not really an option for Drupal core

10. SAX in PHP
• Available in PHP 4 & PHP 5 ( --with-xml )
• Closest “built-in” support
• (hence what we use in Drupal)
• http://php.net/xml

11. SAX example

12. SAX example (cont.)

13. SAX example (cont)

14. SAX example (cont)

15. SAX drawbacks
• Awkward maintain state across events
• Requires prior knowledge of the document
• Maybe not so simple (lots to code)

16. Enter SimpleXML

17. SimpleXML
• DOM-based processing - including xpath
• Included in PHP5
• And, um, it’s simple

18. SimpleXML example

19. Example file

20. SimpleXML example

21. XPath example

22. SimpleXML
+
drupal_http_request() ftw

23. simple webservices

24. When SimpleXML isn’t
simple

25. namespaces

26. Example file

27. Namespaces example

28. maybe it’s not so bad

29. XML Writing

30. XML Writing example

31. Advantages for Drupal
• Shorter, cleaner code (think cleaner
aggregator.module, etc)
• Manipulatable DOM structure (think
hook_xml_alter)
• XML Writing (think node_feed, etc)

32. Thanks, PHP5