[Juser] Lost messages

Alois Mahdal Alois.Mahdal.1-ndmail at zxcvb.cz
Thu Jan 23 22:02:24 UTC 2014


On Mon, 20 Jan 2014 08:06:02 +0100
Torsten Bronger <bronger at physik.rwth-aachen.de> wrote:

> Hallöchen!

Dobrý den!


TL;DR:  If I had this kind of problem, I'd talk to my service
        provider. (Luckily I don't have to, I pay for it and
        it works every time I need it.)


> While chatting with a buddy who is using Xabber on his
> smartphone and I'm using Gajim on my desktop, we frequently
> experience lost messages.  Is this an inherent property of
> XMPP, or can this situation be improved?

:-) Yes, this is inherent property of XMPP, as it is inherent
property of network, as is inherent property of world (unless
you have degree in Quantum Physics).

OTOH, XMPP, as many other protocols is designed to help both
servers and clients to minimize the risk as much as possible.
So it's up to servers and their owners to ensure they are doing
most for their customers.

Regarding the clients, I haven't used these two extensively but
I guess they are both pretty mature pieces of software so unless
using really experimental versions, I would not suspect them.


> Fortunately, both clients *tell* us about lost messages.  But
> it would be much nicer if they didn't happen.  Apparently, it
> happens when my buddy loses his uplink connection.  Then, he
> appears still online in the roster.

Apparently he disconnected before Xabber was able to tell his
XMPP server that he is leaving.  Since the connectivity is
usually geographically constrained, this is inherent to all
mobile devices.  It's up to his server to decide how long to
wait before sending out the message that he has disconnected.


> But messages can't get through for obvious reasons.  I
> thought that they are stored on the server and delivered
> at a later time, but this doesn't happen.

This is possible, but AFAIK not default for most free public
servers.  There are more reasons for this.  First, the messages
need to be stored somewhere, which costs money.  Then, some
people would not like if their messages were stored any longer
than necessary.

Last but maybe most, XMPP was designed for real-time
low-latency usage like Instant Messaging, where it's common
that if the message is important and was not delivered, you
just use another channel (call the person if you need
acknowledgment immediately, use e-mail otherwise) anyway, so
delivering message hours later usually makes little sense.

On the other hand, if you want this feature, you can always talk
to your service provider.


Thanks,
aL.
-- 
Alois Mahdal


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