[Typo3-dev] Help needed with Backend-Programming for Book Database

[Mario Birkigt]

Hello,

for my extension Book Database i get information about a book from 
amazon according to the isbn number of the book. This should serve as a 
help for input of data. As i'm rewriting some parts of the extension, i 
would like to achieve the following benaviour in the backend:
On the standard input form (based on TCEForms) i would like to have an 
additional button, which calls a user-defined function, which retrieves 
the information from amazon, according to the filled information in the 
field isbn. After this function returns, the input fields are 
initialized with the retrieved values from amazon. Now the book can be 
saved to the database in the common way.
I tried to go through the implementation of class.t3lib_tceforms.php and 
  class.t3lib_tcemain.php, but i'm not able to figure out the needed 
information.
Any hints for the solution of this problem would be appreciated.

Greetings

Mario