[Standards] MAM: Conflicting storage prefs behaviour

Ruslan N. Marchenko me at ruff.mobi
Mon Feb 20 20:47:09 UTC 2017

On 19.02.2017 22:49, Matthew Wild wrote:
> An example implementation of storage de-duplication, let's say you
> have two users: userA and userB.
> userA sends a message to userB, which the server archives, because
> both of them have archiving enabled. When processing the message from
> userA, the server gives the stanza a unique ID and stores it in a
> global stanzaStore. It then adds a record to userA's archive, which
> includes the ID of the stanza in the stanzaStore.
> When delivering the stanza to userB, it adds a record to userB's
> archive, and with the same ID in the record. Both users now have the
> stanza "in" their archive, but it is only stored once, in the server's
> central stanzaStore.
> Now userB decides to disable archiving (with userA, or with all
> contacts, it doesn't matter).
> The same thing still happens as before, but this time no record is
> added to userB's archive. If they perform a query, no messages will be
> returned. They are still stored (because userA requested that) but
> userB cannot see them.
> Does this make sense?
Yes, thanks for the hint Matthew, so basically we still trigger the 
archiving per account, however on first archival of any given stanza we 
add meta-field to the stanza saying it's archived (eg. UID).
So later if any other user account's prefs fit archiving condition for 
the stanza - we just store a reference - because we see metadata saying 
it's already stored.
> XEP-0313 explicitly does *not* allow you to prevent your contacts
> archiving your messages (this is impossible to do), so if you contact
> has archiving enabled and you don't want that, there is nothing you
> can do. The preferences in XEP-0313 are only about controlling *your*
> archive.
Yes, that's clear, I was rather asking whether archiving more than 
requested (or ignoring user prefs to archive what it asked not to) would 
be considered as violation of the idea of the xep or it's acceptable 

On a last note - these prefs are supposed to be non-volatile or being 
session object and set up during each session initialisation? Since 
client will likely try to resync the archive - it will also likely try 
to resync the prefs.
So question is probably more in the area of whether or not to archive 
offline messages.


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