In What scenarios you use a DOM parser and SAX parser?
1) If you do not require all the data from the XML file then SAX approach is most preferred than DOM as DOM can quiet memory intensive. In brief if you require large portion of the XML document it's better to have DOM.
2) With the SAX parser you have to write more code than DOM.
3) If you want to write the XML into a file then DOM is the efficient way to do it.
4) Some time you only require validating the XML structure and do not want to retrieve any Data for those instances SAX is the right approach.