When Flash Remoting was first introduced, you had no choice but to use either ColdFusion MX (which comes with Flash Remoting) or purchase Flash Remoting MX for J2EE (Java) or .NET from Macromedia. The reason for this was that the protocol used by Flash Remoting, Action Message Format (AMF), is proprietary to Macromedia and they chose not to release any specifications about it.
Since then, a resourceful programmer named Wolfgang Hamann managed to reverse engineer AMF. Soon after AMF was decoded, an open source project with the goal of creating a fully compatible PHP-based Flash Remoting gateway was born. This project, AMFPHP (http://www.amfphp.org), is well on its way to meeting its goal. At the time of this writing, AMFPHP supports connecting Flash to specially defined PHP classes or SOAP-based web services.
There are a few other open source projects that have applied Wolfgang's work to other languages. These include OpenAMF (http://www.openamf.org), a Java implementation, and FLAP (http://www.simonf.com/flap), a Perl implementation.
This chapter covers how to install AMFPHP on a server and write PHP classes that AMFPHP can utilize. In addition, this chapter examines a few of the more common uses of PHP with Flash.
It's important to note that AMFPHP is a fluid project, so for the final word on its current features be sure to check the documentation on its web site.