Someone else will have to speak toward the MH-E side of things, but
speaking in terms of pure nmh ...
I use nmh with mh-e as front end, and get regularly ics files. When
getting such a file I would like to do the following:
1 a) Add the event to my google calendar;
b) Make an update to an existing event in my google calendar
We don't have any native tools for interfacing with an server speaking
the CalDev network protocol, which is sounds like is what you want for
this piece. I see there is a project called "calendar-cli" which might
do that.
The one piece I wish we did here was have mhical convert a "request"
into a pure calendar entry, for the case where I use nmh to reply to
the calendar request but want to add it to my calendar (basically, strip
out the method line). I keep meaning to bring that up to David (who
wrote mhical) or do that myself, but now is a good as of a time as any
to mention it, I suspect.
2 a) Add it to the emacs diary file;
b) Make an update to an existing entry in emacs diary;
It seems like you could use mhical to extract out the bits from the
calendar entry so it was what emacs needed.
3) Acknowledge / accept / reject the event;
You can do this natively in nmh. You can look at "replaliases" in
the nmh contrib directory for "replaliases" that has the shell aliases
"calaccept", "caldecline", "caltentative", "cancancel" (I do not believe
iCalendar supports an "acknowledge" response). The shell aliases
end up running something like this:
% repl -noformat -editor mhbuild \
-convertargs text/calendar '-reply accept -contenttype' <message>
--Ken