Re: Does IIS5/6 support MDTM command?

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Date: Thu, 18 Nov 2004 09:03:57 -0800

"Alan T" <AlanT@discussions.microsoft.com> wrote in message
news:0B7BD82E-EE19-436A-9E53-46829E81A181@microsoft.com...
> Do you mean although IIS 5/6 support this command, it still doesn't allow
> user to modify the timestamp of the file as this action hasn't been
> allowed
> to made into RFC. Does IIS just support command in RFC (how about other
> draft?) Can I find any documentation in Microsoft talking about any RFC
> supported in IIS 5/6?

To clarify:

The MDTM command is in an Internet-Draft, and has not yet made it into RFC
form.

The operation you are looking for, to set the modification time by the MDTM
command, is not documented in an Internet-Draft _or_ an RFC, because it is
potentially unpredictable. You are asking for a feature that is completely
undocumented, and known to be unreliable even when implemented as you
describe.

> Actually, the reason why I post this message is one user incident:
> He tried to use "synchronization feature" in dreamweaver to compare &
> synchronize the file in FTP server & his PC. However, it seems not stable
> when using this feature (Sometime it can detect the different timestamp of
> the file but sometime can't). So I just suggest him don't rely on this
> feature on my FTP server. Am I correct?

That may be an issue with his client software - the FTP server in IIS does
not support changing the modification time of files. There are a number of
other ways to achieve this, but not through FTP. One way, for example,
would be to upload a .ZIP file through FTP, and have someone local to the
site unzip the file, preserving the modification time.

> Since I know that other FTP servers support this feature (e.g. Serv-U
> FTP),
> user may claim my FTP server is not user-friendly.

Users may just as correctly claim that Serv-U's support of MDTM to change
the modification time could lead to some inconsistencies between behaviour
and intent. Different FTP server authors will make different choices as to
which operations are justifiable, and which cause sufficient concern that
they should not be implemented. Note, for instance, that the Internet-draft
describing MDTM's behaviour was written by the author of an FTP server, and
was reviewed, discussed, edited and approved by the IETF FTP Extensions
Working Group, which consists of authors of FTP implementations - server and
client. Discussion on that group included discussion of this feature, and
it was decided that, since the feature contained possibilities for
inconsistent and unpredictable behaviour, it was not worth documenting in
the Internet-Draft.

There has been discussion among the FTPEXT WG members as to how best to
provide a feature to set attributes of a file, including the modification
time, and there will possibly be a further Internet-Draft (that will
eventually become an RFC) to describe how this can be done. Until then,
there is no documented standard way to alter the modification time of a file
through FTP.

You can even look on this as a security feature, in that you are able to
tell at what time the file was really uploaded through FTP, rather than what
time the user wanted you to think it was uploaded. This feature is also
used by FTP mirroring software to ensure that files are correctly updated
only when necessary.

Alun.
~~~~

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