Registration of mqtt/mqtts URI schemes #227
Description
The wiki associated with this GitHub repo appears to be the most authoritative source for the definition of the mqtt and mqtts URI schemes, at https://github.com/mqtt/mqtt.org/wiki/URI-Scheme. Based on the history of that page, the URI schemes have been in use in substantially the same form for over 11 years now.
However, the schemes aren't registered with IANA and thus don't actually appear in the table of valid URI schemes they maintain. While that doesn't reduce their usability in most contexts where the URI is simply a string, registration would help with applications and protocols that want to have a table of expected possibilities and help avoid any competing definitions.
I believe the appropriate status would be "Provisional", since:
'Provisional' registration can be used for schemes that are not part of any standard but that are intended for use (or observed to be in use) that is not limited to a private environment within a single organization. 'Provisional' registration can also be used as an intermediate step on the way to 'permanent' registration, e.g., before the scheme specification is finalized as a standard.
While MQTT is a standard, the URI scheme is not defined in any current version of that standard that I've found, so I think that accurately reflects its state. As a First-Come-First-Served registry, the bar for creating a provisional entry is incredibly low. While it is recommended to include a summary of any ways in which the scheme deviates from the requirements for "Permanent" registration, even that isn't actually required, and at a quick glance I think this would meet them anyway.
The registration request can be made at https://www.iana.org/form/protocol-assignment.