On PHPMaster.com today there's a new tutorial from Timothy Boronczyk about using the proc_open function to kick off processes outside of PHP. It can be used to start up and manage (in a limited fashion) external process calls.
There are many ways we can interact with other applications from PHP and share data; there's web services, message queuing systems, sockets, temporary files, exec(), etc. Well, today I'd like to show you one approach in particular, proc_open(). The function spawns a new command but with open file pointers which can be used to send and receive data to achieve interprocess communication (IPC).
He starts off explaining one of the fundamental concepts behind working with processes - pipes, both anonymous and named. He then moves on to the use of proc_open and the three attributes it takes - command, pipes and references for output. He includes a more practical example showing it in use - a script that converts text with wiki markup into HTML output (via this tool).