Subject: RE: error codes

From: Doug Royer <[email-masked]>
Date: Fri, 9 Apr 1999 13:51:30 -0700 (PDT)

> Date: Fri, 9 Apr 1999 09:14:16 +0200
> From: Patrik Fältström  <[email-masked]>
> 
> Regarding error codes, please check the discussions / drafts etc from 
> the ftpext working group working with internationalization and 
> standardization of ftp.
> 
> There might be some ideas you can borrow from that wg.

Thanks!

I have included some of that draft below - more information is in
the ftpext draft in section 4.

An excerpt from FTPEXT (draft-ietf-ftpext-intl-ftp-06.txt):

4. Language Support

  The Character Set Workshop Report [RFC2130] suggests that clients and
  servers SHOULD negotiate a language for "greetings" and "error
  messages". This specification interprets the use of the term  "error
  message", by RFC 2130, to mean any explanatory text string returned by
  server-PI in response to a user-PI command.

  Implementers SHOULD note that FTP commands and numeric responses are
  protocol elements. As such, their use is not affected by any guidance
  expressed by this specification.

  Language support of greetings and command responses shall be the
  default language supported by the server or the language supported by
  the server and selected by the client.

  It may be possible to achieve language support through a virtual host
  as described in [MLST]. However, an FTP server might not support
  virtual servers, or virtual servers might be configured to support an
  environment without regard for language. To allow language negotiation
  this specification defines a new LANG command. Clients and servers
  that comply with this specification MUST support the LANG command.

4.1 The LANG command

  A new command "LANG" is added to the FTP command set to allow server-
  FTP process to determine in which language to present server greetings
  and the textual part of command responses. The parameter associated
  with the LANG command SHALL be one of the language tags defined in RFC
  1766 [RFC1766]. If a LANG command without a parameter is issued the
  server's default language will be used.

  Greetings and responses issued prior to language negotiation SHALL be
  in the server's default language. Paragraph 4.5 of [RFC2277] state
  that this "default language MUST be understandable by an English-
  speaking person". This specification RECOMMENDS that the server
  default language be English encoded using ASCII. This text may be
  augmented by text from other languages. Once negotiated, server-PI
  MUST return server messages and textual part of command responses in
  the negotiated language and encoded in UTF-8. Server-PI MAY wish to
  re-send previously issued server messages in the newly negotiated
  language.

 The LANG command only affects presentation of greeting messages and
  explanatory text associated with command responses. No attempt should

 be made by the server to translate protocol elements (FTP commands and
  numeric responses) or data transmitted over the data connection.

  User-PI MAY issue the LANG command at any time during an FTP session.
  In order to gain the full benefit of this command, it SHOULD be
  presented prior to authentication. In general, it will be issued after
  the HOST command [MLST]. Note that the issuance of a HOST or REIN
  command [RFC959] will negate the affect of the LANG command. User-PI
  SHOULD be capable of supporting UTF-8 encoding for the language
  negotiated. Guidance on interpretation and rendering of UTF-8, defined
  in section 3, SHALL apply.

  Although NOT REQUIRED by this specification, a user-PI SHOULD issue a
  FEAT command [2389] prior to a LANG command. This will allow the user-
  PI to determine if the server supports the LANG command and which
  language options.

  In order to aid the server in identifying whether a connection has
  been established with a client which conforms to this specification or
  an older client, user-PI MUST send a HOST [MLST] and/or LANG command
  prior to issuing any other command (other than FEAT [2389]). If user-
  PI issues a HOST command, and the server's default language is
  acceptable, it need not issue a LANG command. However, if the
  implementation does not support the HOST command, a LANG command MUST
  be issued. Until server-PI is presented with either a HOST or LANG
  command it SHOULD assume that the user-PI does not comply with this
  specification.

 .... more in the FTPEXT draft...

-Doug
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