New button in XD01/XD02/XD03


I want to add a new button to XD01/XD02/XD03.

I heard about BADIs CUSTOMER_ADD_DATA and CUSTOMER_ADD_DATA_CS and SPRO "Prepare modification-free enhancement of customer master record" but these seem to be used to add custom sub-screens with extra fields to the transaction.

I just want a new button which will trigger call to a web service. I don't want any new tab or sub-screen.

Should I still use those BADIs? If so, how? If not, what are the alternatives?

Thanks in advance,