Today, you have had a very quick and necessarily brief introduction to XML and the APIs and technologies available in J2EE to parse and generate XML data. You have seen how XML can be used to create flexible structured data that is inherently portable. With DTDs and schemas, you appreciated how this data can also be validated. You have been introduced to several different ways of parsing an XML document with SAX, DOM, or JAXB, and you should now recognize the advantages and disadvantages of each technique.
Tomorrow, you will extend your XML knowledge to include XML transformations.