1. A parser for XML Documents
SAX
A parser for XML Documents

2. XML Parsers What is an XML parser? Software that reads and parses XML
Passes data to the invoking application
The application does something useful with the data

3. XML Parsers Why is this a good thing?
Since XML is a standard, we can write generic programs to parse XML data
Frees the programmer from writing a new parser each time a new data format comes along

4. XML Parsers Two types of parser SAX (Simple API for XML)
Event driven API
Sends events to the application as the document is read
DOM (Document Object Model)
Reads the entire document into memory in a tree structure

5. Simple API for XML

6. SAX Parser When should I use it? When should I use something else?
Large documents
Memory constrained devices
When should I use something else?
If you need to modify the document
SAX doesn’t remember previous events unless you write explicit code to do so.

7. SAX Parser
Which languages are supported?
Java
Perl
C++
Python

8. SAX Parser Versions SAX 1 introduced in May 1998
SAX 2.0 introduced in May 2000 and adds support for
namespaces
filter chains
querying and setting properties in the parser

9. SAX Parser Some popular SAX APIs
Apache XML Project Xerces Java Parser
IBM’s XML for Java (XML4J)
For a complete list, see

10. SAX Implementation in Java
Create a class which extends the SAX event handler
Import org.xml.sax.*;
import org.xml.sax.helpers.ParserFactory;
Public class SaxApplication extends HandlerBase {
public static void main(String args[]) { }

11. SAX Implementation in Java
Create a SAX Parser
public static void main(args[]) {
String parserName = “org.apache.xerces.parsers.SAXParser”;
try {
SaxApplication app = new SaxApplication();
Parser parser = ParserFactory.makeParser(parserName);
parser.setDocumentHandler(app);
parser.setErrorHandler(app);
parser.parse(new InputSource(args[0]));
} catch (Throwable t) {
// Handle exceptions }

12. SAX Implementation in Java
Override event handlers of interest
Public class SaxApplication extends HandlerBase {
public void main (String args[]) {
// stuff missing }
public void startElement(String name, AttributeList attrs) {
// Process this element

13. SAX Implementation in Java
Other events generated by the parser
startDocument()
endDocument()
startElement()
endElement()
error()

14. For more information... java.sun.com/xml www.megginson.com/SAX