[Asterisk-Users] Howtos on writting applications or modules ?

[Robert Rozman]

Hi,

I'm particularly interested in extending some of existing modules, like
cdr_csv for example. I've taken a closer look at the source and I see, that
it registers subroutine to get called to deal with CDR data.

I have following more general questions regarding app or modules API:
- where could I find more info on modules API ?
- what types of modules exist (like maybe modules that are called only on
certain events, then modules that are called in certain time intervals
etc...)
- what existing modules are good examples of different types to start at ?
- if I open tcp port in one module - can I use it in another module ?

Thanks in advance,

Robert.