Lilypond API

[M . Andria]

Hi,
My company is working on a university project that involves management of very 
large music database ; we are using Lilypond to generate png images (programs 
written in C and also inside PHP scripts).
As far as i know, the only way to call Lilypond is through the command line, 
which not optimal in the context of our project, mainly for performance and 
error management reasons (the system is supposed to be able to handle quickly a 
large number of concurrent calls).
We are wondering wether an API for lilypond exists. The answer seems to be 
no... so i would like to ask you : Does it make sense to have this kind of 
feature (if no, how to deal with performance issues) ? do you plan to develop 
this in the future ?

Thank you for your answer.
Regards,

M. Andria