With IDMA and LotusScript addition of NotesHTTPRequest, the ability from a local replica on IDMA to call a REST service on the server replica is useful. But it's important to have the host name and domain name, and ideally the port (although that should always be HTTPS). Yet we don't want to hard-code that into the design.
The good news is NotesSession has a internethostname property and internetdomainname property. Together, this works to allow me to the key first part of the URL, to which the filepath can be appended. But they're undocumented and unsupported.
Now with the rise of NotesHTTPRequest, they have added benefit though.
I accept I've only tested in a limited environment and there may be scenarios or setups where the current implementation doesn't return the right value. So it might not be just a case of adding them into the help and typeahead support.
For completeness, it would be useful to have them exposed in Java too.
Obviously Node.js will already need those details in the configuration of the application, so they're not appropriate to that language.