[Asterisk-Dev] How do I start developing on Asterisk ?

[asterisk at sipspain.com]

Hi,

I have some experience administrating Asterisk, but I neved did custom
programing on it. I would like to start on this field and do my own
programs.

Would like to hear any suggestion about what documentation to follow or
what to read to start dealing with that. I was unable to find any reference
or guide to modules / intresintics of Asterisk that could help....

What I would like to do is something similiar to the "Agent Assistant"
describibed here ->
http://www.alcatel.com/smb/Pages/Products/OmniPCXOffice/pages/voice_callcenter.htm
  I think that funtionality would be great at asterisk, and I would like to
start doing something similiar.

I would do a kind of user-friendly interface (on Visual Basic or similiar)
running on Win32, that interfaces with asterisk. This desktop application
would providessession control, personal and group activity and screen
pop-ups. The agent can access information such as called and calling
number, and call-waiting time in the queue; he can also view the number of
calls that are waiting for the various groups.

I known that is "too ambitious" for a beggining, so initially I would
program only some basic funtions, as being able to "reverse lookup" a
database of contacts trought the CallerID and show info of the person
calling on the agent, so I can choose either pickup up the phone or not. I
would have a button that would also launch an URL with the callerID of the
person calling, so I will be able to interface with my intranet.... and
finally, having a buttton to transfer the call to another operator if i
decide so.....and also a button that can mark my position as "busy" or
unavaiable, so no more calls are distributed to my phone... The final idea
is to having something so complex as the agent showed at previous URL.

Any indications on what to use to develop that ? How I would interface from
my "agent" with asterisk ?

thks