# Re: FTP syntax

Tim Berners-Lee (timbl@ptpc00.cern.ch)
Tue, 22 Mar 94 17:51:49 +0100

- Messages sorted by: [ date ][ thread ][ subject ][ author ]
- Next message: Josh Osborne: "Re: Reliable links [Was: Stab in the dark ]"
- Previous message: Mark P. McCahill: "the one comment I got about nntp section..."
- Maybe in reply to: Mitra: "FTP syntax"
- Next in thread: hallam@alws.cern.ch: "Re: FTP syntax"

    Date: Tue, 22 Mar 94 17:51:49 +0100

    From: Tim Berners-Lee <timbl@ptpc00.cern.ch>

    Message-Id: <9403221651.AA13731@ptpc00.cern.ch>

    To: <uri@bunyip.com>

    Subject: Re: FTP syntax

Summarizing, the consesnus is now that the FTP syntax should be
of the form

ftppath <fpath> [ <separator> <mode> ]

<fpath> <xpalphas>

<separator> (we have been talking about a colon)

<mode> dir | bin | text | tenex

where if the mode is omitted the client has to do its best to figure it out.

Now all we have to do is to make this wholsesome. You obviously
must allow any character in the xpalphas bit. So that means that the
separator (like colon) must be escapable. Now the rules for
escaping characters in URLs are such that reserved characters
like / have different meanings when escaped, but other characters
not explicitly reserved MAY be escaped if the medium in question
doesn't like them.

[background: This is what gave us the flexibility to arrive
at consesus on the character set issue in Amsterdam. It allows
software to display Latin-1 characters to people, but encode them
in mail. It allows Gopher and HTTP to have slightly different
excluded sets. But it does define a connonical form for standard
interchange. In other
words, if you come across %20 in a URL or you come across " "
you must treat them the same. But if you come across %2F and "/"
you must treat them differently. This allows us lattitude
and also avoids the yukky prospect of escaped escape sequences]

Now it is no good if some gateway unescapes the separator, so the separator
must be from, or added to, the set of reserved characters. Currently
this set is

{ | } | / | # | ? | vline | [ | ] | \ | ^ | ~ < | >

but does NOT include the "extra" characters (from Amsterdam)

! | * | " | ' | ( | ) | : | ; | , | space

where space in now disallowed in connonical form (Houston).
What I suggest is that just as now, for other schemes we are
going to need some separator characters, and we grap them now
while we have the chance. For example, suppose we take

! and *
and say that they are reserved, and may not be used unescaped
except when having special meanings (to be defined). This would allow

ftp://info.cern.ch/pub/www/doc/draft-www-bernerslee-uri-00.text!text

The change to the safe character set would not affect very many URLs
at this stage.

I wouldn't be in favor of doing this to ":" as I am sure it turns up
in current URLs a lot more than "!".

[The only alternative I see is to use as a sparator any of the
non-hex & sequences, which are currently all reserved, such as

ftp://info.cern.ch/pub/www/doc/draft-www-bernerslee-uri-00.text%:text

but this is I think more messy.]

Summary of proposal:

1. ! and * reserved
2. separator is !
Ok?

Tim BL

- Next message: Josh Osborne: "Re: Reliable links [Was: Stab in the dark ]"
- Previous message: Mark P. McCahill: "the one comment I got about nntp section..."
- Maybe in reply to: Mitra: "FTP syntax"
- Next in thread: hallam@alws.cern.ch: "Re: FTP syntax"