[Standards] XEP-0184: <received/> vs. <displayed/> vs. <read/>

Kevin Smith kevin at kismith.co.uk
Sat Jun 19 08:37:17 UTC 2010

On Thu, Jun 17, 2010 at 2:29 PM, Konstantin Kozlov <yagiza at yandex.ru> wrote:
>> On Wed, Jun 16, 2010 at 8:10 PM, Konstantin Kozlov <yagiza at yandex.ru>
>> wrote:
>>>  Yes. Let's sort out what means "received", "displayed" and "read" to
>>> decide which of them are needed and which are not.
>> Yes.
>> So:
>> What's the use case for needing to know when the user's client has
>> received the message?
>   If sender wants to be sure, that client on the other side received and
> processed the message. So, the sender is sure that once the user on the
> other side will pay attention to its client application, he'll be able to
> read the message.
> If delivery of all the previous messages were confirmed by the <received />
> reply and THIS one was not, the sender may assume, that the message was lost
> somehow and may try to resend it (if he wants).

OK - can you tell me how this need is better met by this behaviour
than by XEP-0198? 198 gives much firmer guarantees on delivery than
this method does.

As we discussed at length  in the last review of 184, receipts here
are very vague. If you receive a receipt then you know that the user
has had the message displayed to them (or received by the client,
depending how you interpret the text). The converse is not true - if
you don't receive a receipt you can't derive anything from this except
that you haven't had the receipt yet.

Note that we could write a XEP that has more reliable end to end acks
if that would give us more reliability than just implementing 198 (The
text in 184 hints at the possibility).

>> What's the use case for needing to know when the user has been shown
>> the message?
>   I don't know. For me knowing that message was displayed on the other side
> is absolutely useless.

Ok. Does anyone disagree and want this information?

>> What's the use case for when the user must have read the message?
>   For me, knowing, that user on the other side read the message is very
> useful. 'cause if I got <received /> confirmation from the other side, but
> getting no <read /> confirmation from the other side for a long time, I'll
> assume that user didn't noticed notification of my message arrival. So, I'll
> try to attract his attention, for example, using XEP-0224 (Attention).
> <http://xmpp.org/extensions/xep-0224.html>

I can see two cases here
1) The user doesn't need a reply urgently
2) The user needs a reply urgently.

As I see things, if (1) is true, there's no need to go sending 224
pokes to get a response, and in (2) you'd send a 224 poke (if you were
so inclined) irrespective of whether you get a read receipt or not if
you didn't have a reply. Is that reasonable?


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