Re: Two FTP issues

[Carsten Bormann <[e-mail]>]

Hi John,

I believe a hard-earned piece of experience I took from using FTP is that you don’t want to do conversions during transit.

In theory, the sending system knows its format, can convert that to a common format, and the receiving system knows its own format and can do the second conversion.  That was certainly true when we had access methods, per-record byte counts etc.

In practice, systems today have files of various formats lying around, no useful metadata so no idea what the actual source format is, so they are likely to botch the conversion.  Getting the original bytes from the sending system and doing the conversion at the receiving end, outside the actual transfer, became the norm.  I don’t remember when ftp clients started to automatically send “TYPE I” on connection setup, but it sure made life so much easier (read: FTP became somewhat usable again).

This is probably one instance of the more general gateway fundamental.  Instead of needing gateways between various mail systems, everything converged to SMTP, or being as close to SMTP as possible (i.e. requiring minimal gatewaying/conversion).

This has also happened in text formats (with the exception of the remaining two line ends, and, with a lesser relevance, interpretation of HTs).  Anything that tries to make life easier for systems that aren’t UTF-8 yet is like adding another transition technology to IPv6: trying to be helpful, but in practice counterproductive.

Grüße, Carsten