12     XML & XSLT

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We all know that XML has great advantages going for it - it is human-readable, cross-platform, and easily converted into other forms. However, we all also know that it is not the fastest kid on the block when put up against binary formats.

So, how does a web developer harness the power of XML, whilst retaining as much performance as possible? Simple - use PHP's exceptionally fast XML module!

This chapter will teach XML parsing and manipulation using PHP, and requires that you are familiar with PHP as a language. Some familiarity with XML is required, although XML syntax and grammar is not mentioned in detail - the focus is PHP.

Topics covered in this chapter are:

• Standard XML manipulation

• "SimpleXML" - the fast and easy way to use XML

• XSL and transforming XML

Chapter contents

12.1. Introduction to XML
12.2. Event-based parsing

12.2.1. Creating a parser: xml_parser_create() and xml_parser_free()
12.2.2. Getting to know callback functions
12.2.3. Callback function implementation
12.2.4. Event-based XML parsing, at last!
12.2.5. Bringing Everything Together

12.3. SimpleXML

12.3.1. First steps
12.3.2. Reading from a string
12.3.3. Searching and filtering with XPath
12.3.4. Outputting XML: asXML()

12.4. Transforming XML using XSLT

12.4.1. Adding PHP to the mix
12.4.2. Handling the processed output
12.4.3. Making XSL work for its money
12.4.4. What else can XSL do?
12.4.5. XSLT Conclusion

12.5. Summary
12.6. Exercises
12.7. Further reading
12.8. Next chapter