I have an mPos android app I'm working on which basically requires reading from the EMV chip card to perform transactions. I understand the concept of sending application protocol data unit (APDU) commands to the chip and receiving APDU responses in return. However I am lost and confused as I don't know the exact APDU commands to send to the chip when I need to perform a financial transaction. I have read some of the official EMV docs and also spent days googling but I couldn't find what I was looking for. Any pointers and help would be greatly appreciated.
Go to EMV Book 3 chapter 8, that is the location of the EMV financial transaction flow chart. That will help you know how to start and complete a transaction with an EMV card. Then also check out Chapter 10 of the same book, which specifies the functions used in transaction processing, and how to actually start one. The book will point other books for reference to you where applicable, and you may also need to refer to extra books for additional info. Some useful links include:
Hope that points you in the right direction