[NNTP] Re: [ietf-nntp] draft-ietf-nntpext-streaming-01.txt

[Ken Murchison]

Russ Allbery wrote:

> Ken Murchison <ken at oceana.com> writes:
> 
> 
>>After thinking about this some more, should we even bother discussing
>>MODE STREAM as a formal part of the STREAMING extension?  Since we all
>>agree that MODE STREAM has been historically used as a capability
>>discovery mechanism, which is now deprecated by LIST EXTENSIONS, what's
>>the point of formalizing it?  I can see possibly documenting it as an
>>obsolete command somewhere in the document, but including it as part of
>>the STREAMING extension seems wrong.
> 
> 
> I'm worried about transition issues.  I believe there are implementations
> that will reject CHECK/TAKETHIS unless MODE STREAM has been sent first, so
> I'd like to warn implementors that for backward compatibility, they should
> implement MODE STREAM on the receiving end even if it's a no-op and send
> it before using CHECK/TAKETHIS.  (While strongly discouraging this
> implementation method in the future, of course.)

Here's the text that I've come up with for MODE STREAM:


2.2. MODE STREAM Command

      This command is deprecated and is only documented for compatibility
      with legacy implementations of the STREAMING extension.  New client
      and server implementations are not required to support this command
      but they are encouraged to do so.

2.2.1. Usage

      This command MUST NOT be pipelined.

      Syntax
         MODE STREAM

      Responses
         203   Streaming permitted

2.2.2. Description

      A client issues the MODE STREAM command to indicate that it wishes
      to use the CHECK and TAKETHIS commands instead of, or in addition
      to, IHAVE.  If the server supports the CHECK and TAKETHIS commands
      a 203 response MUST be returned.

      If a server advertises the STREAMING extension label in the LIST
      EXTENSIONS response, the MODE STREAM command is not required and a
      client SHOULD NOT issue it.  If a legacy server does not support
      the LIST EXTENSIONS command or does not advertise the NNTPv2
      extension label, a client SHOULD issue the MODE STREAM command
      prior to using the CHECK or TAKETHIS commands.

      A server MUST NOT require that the MODE STREAM command be issued
      before accepting the CHECK or TAKETHIS commands.  A server SHOULD
      accept the MODE STREAM command for compatibility with legacy
      clients which don't use the LIST EXTENSIONS discovery mechanism.

-- 
Kenneth Murchison     Oceana Matrix Ltd.
Software Engineer     21 Princeton Place
716-662-8973 x26      Orchard Park, NY 14127
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