XML — Parser

DOM Parser

Loads entire XML into memory:

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(new File("books.xml"));

SAX Parser

Event-based, memory efficient:

SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser parser = factory.newSAXParser();
parser.parse(new File("books.xml"), new DefaultHandler() {
    public void startElement(String uri, String localName, 
        String qName, Attributes attrs) {
        System.out.println("Element: " + qName);
    }
});

DOM vs SAX

Feature	DOM	SAX
Memory	Full document	Events only
Speed	Slower load	Faster
Navigation	Any direction	Forward only
Modification	Yes	No

JavaScript Parser

var parser = new DOMParser();
var xml = parser.parseFromString(xmlString, "text/xml");
var titles = xml.getElementsByTagName("title");

Python Parser

import xml.etree.ElementTree as ET
tree = ET.parse("books.xml")
root = tree.getroot()
for book in root.findall("book"):
    print(book.find("title").text)

Mini Practice

1. Parse XML with DOM in JavaScript
2. Use SAX-style parsing
3. Extract data from parsed XML
4. Compare DOM and SAX approaches

Up Next

Continue with AJAX — loading XML with AJAX.