Chapter 1 explained the benefits of a nonproprietary, open standard document format for exchanging information between desktop applications, local server-based systems or software components, remote servers, or all three. One of the primary advantages of text-based documents is their ability to emulate HTML traffic delivered by the HTTP to TCP port 80. Almost all corporate and personal firewalls permit unlimited two-way, HTTP transfer of text that’s encoded as ordinary ASCII characters or their Unicode UTF-8 and UTF-16 counterparts. Firewalls that block port-80 traffic would prevent users with network connections behind the firewall from accessing the Internet.
Blocking XML traffic
It’s possible to block ...