PMI Proposals and Discussion Tomorrow

Hi WG Members,

I've updated the Payment Method Identifier proposal
<https://github.com/zkoch/zkoch.github.io/blob/master/pmi.md> [1] and
written an extension of it proposing a new Payment Manifest
<https://github.com/zkoch/zkoch.github.io/blob/master/payment-manifest.md> [2]
file. I'm hoping we can discuss these on tomorrow's call. Here are the
points worth highlighting:

* It came up in discussion
<https://github.com/w3c/webpayments-method-identifiers/issues/9> that URNs
have minimal value and instead add an extra burden on web developers. This
argument seem strong to me, and as such, I propose we replace URNs with
strings. I realize we have gone back-and-forth on this, but given the
arguments, strings seem best.
* In the same discussion, it was brought up that URLs are only valuable as
identifiers if something lives at that URL. The payment manifest proposal
is an attempt to explain what this could look like and why it's valuable.

For tomorrow's call, I would like to focus on getting consensus on the
following points:

1.) Absolute URLs will be used to identify proprietary payment methods
2.) Strings will be used to identify open payment methods and will be
maintained by the WG
3.) Every payment method must have an associated payment-manifest file (or
similar)
4.) There must be some standard way to access that payment-manifest file
(or similar)

Note that I don't think we need to agree exactly how (3) and (4) should
work right now, we just need to assume that they will exist so we can
unblock work. I hope that leading up to TPAC and during our time together
we can hack out exactly how they should work and meet all of the various
use cases the group cares about.

Looking forward to discussing.

Thanks,

Zach

[1] https://github.com/zkoch/zkoch.github.io/blob/master/pmi.md
[2] https://github.com/zkoch/zkoch.github.io/blob/master/payment-manifest.md