Jeff Mancuso wrote:
FTP and SFTP are file transfer protocols. They open the file only
for the duration of the transfer. Think of it as copy-and-paste.

This isn't actually true. FTP is just a file transfer protocol,
strictly. SFTP isn't a secure version of that archaic protocol, but is
in fact, a totally different protocol that does support file handles.
Allowing an application to interact with an actual open instance of a
file handle on the remote server.

Well, I suppose it depends on which SFTP the OP is talking about. I
was thinking of Simple FTP (RFC 913). It is simply a UDP version of
FTP. That is a little over-simplified; it is a very different
protocol. But the point it, it is indeed just a file transfer
protocol. You are talking about Secure FTP (still just an Internet
Draft). Shame on the IETF for permitting the same acronym! I confess
that I am not familiar with the Secure FTP protocol. Searching
briefly, one online description does suggest that you might be right.

And by the way, FTP is no more "archaic" than TCP is. Yes, the
protocols are old. So is the automobile and airplane. But you depend
on it on a daily basis, if you use the internet a great deal. Simple
FTP, on the other hand, is truly archaic. It is (was?) used while
booting diskless workstations. UDP was a simpler protocol to implement
for embedded systems than TCP. That was in the days when memory chips
were built in "K" increments. (Oh the "joy" in wire-wrapping 8 1Kx1
chips :-.) I doubt that Simple FTP is used at all anymore; which is
why the IETF might have permitted the acronym to be used for Secure
FTP. My bad!