Which is the optimal way of XML parsing(XML may be of large amount of data) in php?
one of the most common ways is SimpleXML. it's pretty easy to use and fast.
See XML and PHP 5 in Devzone for a good introduction.
Basically, if you need to process large volumes of XML files, you will want to use a pull parser, like XMLReader or XMLParser to prevent running into memory issues. Parser like DOM or SimpleXML will read the whole files into memory before you can process them.
If you need a way to parse XML data that is valid for PHP4 too, then you can use the XML parser, or DOM XML (which is a PHP4 only extensions); if you need a solution for PHP5, then you can use DOM, or XMLReader.
It depends from your needs.
i've used SAXY XML parser in the past. try it.