2014-03-21 9:47 GMT+00:00 Andreas Schildbach : > On 03/20/2014 05:14 PM, Alex Kotenko wrote: > > > Hmm, if we're inventing an URI for bluetooth, I'd rather follow existing > > URI's patterns. BT is strictly point-to-point connection, so BT MAC > > should be considered as server address, and payment request ID can be > > considered as request path. Probably "bt:/​ > > " would be more usual and easily > > understandable. > > Agreed. I used the dash because I feared a slash would need to be > escaped if used in an URL parameter. > ​It will need to be ​escaped, but HTTP URLs used in BIP72 have it already, so don't see why we should bother. > > I wonder how complex it would be to implement HTTP-over-Bluetooth. Not > > like I'm willing to do that now, but HTTP is well known and proven to be > > quite good for tasks like this, so in theory it would be handy to have > > such capacities in here. > > Thought of that as well. On the other hand, HTTP might be overkill and > we inherit its potential downsides as well. > ​It definitely is an overkill. Don't think we should do it now unless we will see later during implementation that we really have to. > > Well, do we need to be compatible? If the dev community decides > Base43 > > PR QR's (or whatever other self-contained format) is the way to go, > we > > just implement, roll it out and use it. > > > > My PoS needs to be compatible with BIP21, as when I'm presenting QR code > > or sending NFC message - I have no way to tell what wallet/phone is ​​on > > the accepting side, so I have to be compatible to existing widely > > supported technologies. > > Agreed. All I wanted to say support for QR is still small enough that we > might be able to switch to an incompatible standard. If we're determined > that is. Ok. Btw, I've tested ​QR possibilities on my PoS screen, in binary mode it's limited to about 600 chars, so really I can include only unsigned and rather short payment request. Signed requests longer than few hundred bytes will not work. > > ​Well, yes, it would be less efficient than base43. But did you > > calculate how much less? ​It's a compatible and already widely used way > > and loosing compatibility needs to have serious reasons, so would be > > great to know exact figures here. > > Base 64 via binary QR: 64 chars / 256 chars > ==> 6 bit / 8 bit = 0.75 > > Base 43 via alphanum QR: 43 chars / 45 chars > ==> 5.43 bit / 5.49 bit = 0.99 > > That would be efficiency in terms of PR data size vs. amount space used > in a QR code. Of course, the visual QR encoding also plays a role, for > example its size is increased in discrete steps. > Ok, so base43-aphanum is winning about a quarter of capacity against base64-binary. I probably will skip this anyway and go with bluetooth URI scheme we've just agreed + old style payments over p2p network as fallback. So no payment requests in QR codes at all from my side. > > > > > ------------------------------------------------------------------------------ > Learn Graph Databases - Download FREE O'Reilly Book > "Graph Databases" is the definitive new guide to graph databases and their > applications. Written by three acclaimed leaders in the field, > this first edition is now available. Download your free book today! > http://p.sf.net/sfu/13534_NeoTech > _______________________________________________ > Bitcoin-development mailing list > Bitcoin-development@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bitcoin-development >