Using SRV records with a http Web Service

I am trying to spec out a Web Service. It is obviously desirable to use SRV
based discovery over A-record since that allows for priority, fallback, etc.

However rfc7230 is silent on the matter.

The point of complication that enters is what the name for the Host:
header. Should this be remapped to the address given in the SRV or not? My
view is that it should not.

so if the service being resolved is _mmm._tcp.example.com and we have srv
records:

_mmm._tcp.example.com SRV 0 5 80 host1.example.com
_mmm._tcp.example.com SRV 0 5 80 host2.example.com

The Host: header should be:

Get /.well-known/mmm/
Host: example.com


This seems like the obvious approach. However there are two other
possibilities:

Host: host1.example.com
Host: _mmm._tcp.example.com

The first is obviously unhelpful and wrong as the SRV alias identifies a
machine, not the site.

The second could actually be useful though. It essentially eliminates the
need for .well-known URIs.