Re: Integrate Tramp

[Kai Großjohann]

Richard Stallman <address@hidden> writes:

>     If the default connection method for unknown hosts was 'ftp,
>     ange-ftp would work as today; it could also be the fall-back
>     for 'detect if none of the tramp methods work.
>
> That sounds good.  I have one question, though: how long does it take
> to test the various tramp methods?  I could imagine that if they involve
> trying to open network connections it could take many seconds or even minutes
> to test them.  Can you tell us a definitive answer?

There are a lot of things which could be auto-detected.  For example,
Tramp could auto-detect whether mimencode or uuencode should be used
in an "inline" method.  This kind of thing is fairly quick to test
and, what with all the other auto-detecting that is already going on,
it wouldn't make much of a difference, efficiency-wise.

But I'm not so happy about auto-detecting which program should be used
to connect to the remote host.  Suppose that Tramp tries "ssh", then
"ssh -2", then "ssh -1", then "rlogin", then "telnet" and possibly
also the Kerberized login programs.  First of all, waiting for a
timeout from all these programs could take a long time.  Secondly, it
might result in the user getting asked strange questions.  (Suppose
Tramp tries to log me in to the GNU machines with Kerberos, but I've
never used Kerberos.  Then I'd get asked Kerberos questions which I
don't know how to answer.)¹

Also note that (length tramp-methods) => 30.  Maybe a handful of
these methods are not necessary anymore.  But the lion's share of
them were added by me because they fulfilled a real need.  Maybe this
gives you some idea about the task to do auto-detection.

Another remark:

It would be great if Tramp could auto-detect everything.  But I've
been working on Tramp for a while and so I know that it will take me
a long time to implement all of this.  (If I can do it at all.)  So
my suggestion is to keep "more auto-detection" in mind as a long-term
goal, to work towards this goal in a step-by-step fashion, and to
design the current interface (filename syntax) for Tramp in such a
way that the auto-detection is not necessary for Tramp to work.

I think that Tramp is useful even if it does not do more
auto-detection.

Note: I want to add caching to Tramp so that auto-detection only
needs to happen once for a given user/host combination.

kai

¹ I hope that Kerberos really asks questions.  I don't know, I've
  never used Kerberos.  But this was just intended as an example --
  feel free to replace this example with another one.
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