The smallest addition to package.xml 2.0 is the<channel> tag. Don't be fooled though, channels are the most significant new feature implemented in the PEAR installer. Channels are to PEAR what dependencies are to team development. By opening up the ease of the PEAR installer to sites other than pear.php.net, a number of free choices have been made available to PHP users. For the first time, it is possible to design an application that depends upon packages from pear.php.net, pear.example.com, and any number of sites, and all of them can be automatically downloaded, installed, and easily upgraded on the end-user's computer with a single command. Although Chapter 5 discusses the minutiae of channels and the channel.xml channel definition file, it is good to have a basic understanding of how channels work when designing your packages.
There are two problems that channels effectively solve:
Distributing application development across multiple...
