2014-03-06 16:46 GMT+00:00 Andreas Schildbach <andreas@schildbach.de>:

Supporting Bluetooth is optional in the sense that if a wallet should
not support it, you will still receive the transaction via the P2P
network. So I'd say definately go for Bluetooth.

​Yes, it's part of the​ plan. Just again - I need to make sure we support all major wallets. And no other wallets actually support NFC by now, not talking about bluetooth. So I imagine we will decide and implement together some solution here, both on the wallet and POS sides, but I will have to keep URI method and even QR codes for backwards compatibility, and wait for other main wallets to accept innovations before we will be able to completely switch to it.

As I said earlier - bluetooth support for my POS is not a problem, we can plug it in easily and make it work. Support among all hardware/software and polished user experience - this is a main thing here really.

I wonder about the receipt step -- are you generating a PDF on device

and sending it via NFC? This is something that could be supported by the
BIP70 payment protocol. We should try to avoid the second tap, its not
intuitive.

​No, I'm generating it on server and sending only URL via NFC. I think this area will change before we launch in production. Ideally I want ​the device to be completely autonomous, controlled on site by the merchant, probably with an app on his phone. But right now we have a backend server that gives merchant a dashboard with device configuration control, transactions history, daily reconciliation data and copies of receipts. So the PDF is sent from that server.

​We should avoid second ​tap ideally, but we need to make sure receipts and payment proofs are usable and understandable for both payers and payees.

Right now a paperless PDF-only process is already a huge leap ahead comparing to numerous paper receipts printed for each transaction by existing POS systems. 

Implementing proof of payment based on BIP70 payment request+transaction in the blockchain+memo will require even bigger shift in the merchant's view on how business runs. Also it will need additional software on his side to actually be able to view and confirm these proofs of payment. In theory - yes, BIP70 will create a way to implement proof of payment. In practice in real life right now I don't see it viable, it will take time to adopt and few intermediary steps like PDF based paperless process I've implemented.