XML is quickly becoming the universal protocol for transferring information from site to site via HTTP. Whereas HTML will continue to be the language for displaying documents on the Internet, developers will find new and interesting ways to harness the power of XML to transmit, exchange, and manipulate data using XML. Validation of the XML document and of the messages going to that document is the first line of defense in hack proofing XML. The same properties that make XML a powerful language for defining data across systems make it vulnerable to attacks. More important, since many firewalls will pass XML data without filtering, a poorly constructed and invalidated document can constitute a serious system-level vulnerability. Hack ProofingR XML will show you the ins and outs of XML and .NET security.