Re: [Extra] Eric Rescorla's No Objection on draft-ietf-extra-imap-replace-02: (with COMMENT)

[Stuart Brandt <[e-mail]>]

Thanks, Eric. Comments inline.

On 10/23/2018 8:17 PM, Eric Rescorla wrote:
> Eric Rescorla has entered the following ballot position for
> draft-ietf-extra-imap-replace-02: No Objection
>
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> ----------------------------------------------------------------------
> COMMENT:
> ----------------------------------------------------------------------
>
> Rich version of this review at:
> https://mozphab-ietf.devsvcdev.mozaws.net/D12061
>
>
>
> COMMENTS
> S 2.
>>       handling a REPLACE command, a server MUST NOT generate a response
>>       code for the STORE +flags \DELETED portion of the sequence.
>>       Additionally, servers supporting the REPLACE command MUST NOT infer
>>       any inheritance of content, flags, or annotations from the message
>>       being replaced.  Finally, the replaced and replacing messages SHOULD
>>       NOT be present in the mailbox at the same time.
>
> I don't think I understand this text. What would it look like for them
> to be present at the same time.
>

This wording was a compromise from the original 
draft-brandt-imap-replace-00 that had much stronger language around the 
atomicity of REPLACE.  In discussions just prior to IETF93, the strict 
atomic guarantee was considered a hindrance to adoption by server 
implementors. The "SHOULD NOT" here is intended to *discourage* server 
implementors from allowing clients to discover and therefore act on both 
original and new messages, but acknowledges that in some cases it may be 
unavoidable.

To answer your question more directly, it would look like it looks today 
without the REPLACE extension -- 2 independent messages existing 
concurrently for a moment in time along with the potential issues 
highlighted in the Overview section.