Re: [imapext] SEARCHRES RFC5182

[Adrien de Croy <[e-mail]>]

Hi Alexey

------ Original Message ------
From: "Alexey Melnikov" <[e-mail]>
To: "Adrien de Croy" <[e-mail]>
Cc: "[e-mail]" <[e-mail]>
Sent: 10/03/2021 11:07:25 pm
Subject: Re: [imapext] SEARCHRES RFC5182

>Hi Adrien,
>
>On 09/03/2021 23:21, Adrien de Croy wrote:
>>Hi Everyone
>>
>>I've been looking into this extension, but it has a number of problems 
>>and uncertainties in the spec especially:
>>
>>* in relation to storing results of ESEARCH extensions, it refers to 
>>them as messages).
>Can you elaborate/quote specific text which is confusing?
>


When the SAVE result option is combined with the MIN or MAX [ESEARCH]
    result option, and none of the other ESEARCH result options are
    present, the corresponding MIN/MAX is returned (if the search result
    is not empty), but the "$" marker would contain a single message as
    returned in the MIN/MAX return item.


It's not clear if $ is storing the result of the MIN, or something else. 
  But I guess those are the same for MIN and MAX - the IDs.

$ only stores message IDs, not messages.  Maybe replace "contain a 
single message" with "refers to a single message" or "contains the 
message ID"

I guess I should have read it a few more times.  Maybe it's not so 
unclear.

>
>
>>* in relation to reporting errors if the saved results are 
>>incompatible (e.g. stored SEQ but asked to use as UID or vice versa)
>The document is quite clear that $ references message numbers or UIDs 
>as appropriate in the corresponding context. So a saved result is never 
>incompatible.
>

So we save both UIDs and SEQ and adjust these on expunge, and just use 
whichever one is appropriate in the subsequent commands.

Thanks!

Adrien

>
>
>You can see this in the last paragraph of section 2.1:
>
>    Implementation note: server implementors should note that "$" can
>    reference IMAP message sequences or UID sequences, depending on the
>    context where it is used.  For example, the "$" marker can be set as
>    a result of a SEARCH (SAVE) command and used as a parameter to a UID
>    FETCH command (which accepts a UID sequence, not a message 
>sequence),
>    or the "$" marker can be set as a result of a UID SEARCH (SAVE)
>    command and used as a parameter to a FETCH command (which accepts a
>    message sequence, not a UID sequence).
>
>>* dealing with expunging of messages.
>I think this is also clear, from Section 2.1:
>
>    When a message listed in the search result variable is EXPUNGEd, it
>    is automatically removed from the list.  Implementors are reminded
>    that if the server stores the list as a list of message numbers, it
>    MUST automatically adjust them when notifying the client about
>    expunged messages, as described in Section 7.4.1 of [IMAP4].
>
>
>
>If it helps, the best way of implementing this (IMHO) is to store a 
>list of UIDs in some form and translate them to sequence numbers in the 
>server, when needed. When messages are expunged, this list is purged of 
>expunged messages.
>
>>So my first question relates to whether I'm even wasting my time.  The 
>>imapwiki shows very few servers support it, but are any clients known 
>>to support it?
>I don't know the answer to this.
>
>
>Best Regards,
>
>Alexey
>