Alternative 'tp_info' format using CRIs

[marco-tiloca-sics]

We can consider an alternative tp_info as

    [
       // in absolute form, with no path or query
       CORI (tp_id, srv_host, ?srv_port),
       token,
       // in authority-only form, equivalent to a `//host:port` URI reference
       CORI (cl_host, ?cl_port)
    ]

For consistency, entries in the new Registry "CoAP Transport Information" will have to cross-reference the "Scheme Registry" or anything else suitable for CRIs (see below, including changes to the current registry format).

 +-----------+-------------+--------------+-----------+
 | Scheme    | Description | Req Info     | Reference |
 | (with CRI)|             |              |           |
 +-----------+-------------+--------------+-----------+
 | coap      | UDP is used |  token       | [This     |
 | (-1)      | as per      |  cli (a rel. | document] |
 |           | RFC7252     |     CRI //x) |           |
 +-----------+-------------+--------------+-----------+

• value: replaced with scheme name or what's in the CRI shorthands
• srv addr is always a CRI (so no need to have it in the registry), with scheme and authority with empty path and no query or fragment
• cli is a CRI reference, as used is of shape //authority

[chrysn]

Added a brief note in 4abb04600309c0beabfbf59887d211c6233bd3bd that this will happen, without actually performing the change yet (giving core-href a bit more time to mature).

[edit: repo confusion, it's in https://github.com/core-wg/observe-multicast-notifications/commit/2fed0cd097d565cda61cc8e81b30d93eb028eb0a ]

[chrysn]

I think CRIs are stable enough to use.

[marco-tiloca-sics]

Closed by #14