how to interfacing done using PHP?

[schin]

Hi,

here is some questions:
i need to create a web interface
for an existing application.

There is some functions like
call script to clean up the log.

(1) how php works to interface with
the application, using system()??

(2) based on the case i mentioned above,
how can the system know
how to call the script to clean up
the log?

thanks