RE: Additional thoughts on text transfers

[Richard Whalen <Whalenr%process.com@localhost>]

> -----Original Message-----
> From: nico [mailto:nico%verizon.net@localhost]
> Sent: Wednesday, April 03, 2002 10:05 PM
> To: Richard Whalen
> Cc: 'Markus Friedl'; 'ietf-ssh%netbsd.org@localhost'
> Subject: Re: Additional thoughts on text transfers
> 
> 
> On Tue, Apr 02, 2002 at 09:00:25AM -0500, Richard Whalen wrote:
> > > Then why does everybody write lines and lines of email instead of
> > > writing a draft using the mechanisms provided by
> > > 	draft-ietf-secsh-filexfer-02.txt
> > > 
> > 
> > The mechanisms provided by draft-ietf-secsh-filexfer-02.txt 
> fall short of
> > what is needed to provide a text transfer mechanism.
> > 
> > The file attributes mechanism has plenty of flexibilty to present
> > information about the type of information in the file, and 
> whether or not
> > any translations can be provided.  Right now it says 
> nothing about the type
> > and that no translations are available.
> 
> I don't see why the attributes wouldn't suffice for the case of ASCII
> text files:
> 
> Unix client: open(some file, write|create|trunc, attrs: {..., 
> content-type:
> 			text, encoding: ASCII, eol: LF, ...}, ...)
> 
> VMS server: OK, handle
> 
> client: write(handle, ...)
> client: write(handle, ...)
> ..
> server: OK
> server: OK
> ..
> client: close(handle)
> server: OK
> server: <create/truncate the file, write text sans LF and marking the
> 	 record boundaries where the LF characters were in the original>
> 
> client: open(some other file, read)
> server: OK, handle
> client: stat(handle)
> server: OK, attrs: ... content-type: test, encoding: ASCII, 
> eol: X, ...
> client: read(handle,...)
> ..
> client: close(handle)
> server: OK
> 

> 
> A canonical file format (preferably as a stream of octets) is 
> needed for
> checksumming.
> 
> Perhaps SFTP should move to a different working group :)
> 
> > ----------------------
> > Richard Whalen
> > Process Software
> 
> 
> Cheers,
> 
> Nico
> 


Your example for writing a file is reasonable, though the READ & WRITE
operations have not be defined to allow conversion of data upon storage.

Writing files in the local format when there is a defined text format is the
easy case though.

How do you read a file that is stored in a local format and needs to be
delivered in a defined text format?

The idea of exchanging a checksum to verify that a file has been completely
transferred is good; it could eliminate the need to process the file in the
defined transfer method to get the exact size to check to see if the
complete file has been received.

----------------------
Richard Whalen
Process Software