[JDEV] id attr in message packets

[Ben Schumacher]

On Sun, 14 Jul 2002, Sean Wheeler wrote:
> On Sun, 14 Jul 2002, Jeremy Nickurak wrote:
> >
> > The id attribute is intended to be used so that the sender and receiver
> > can refer to particular messages. For example, someone might implement a
> > "addendum" message type/namespace that changes some element of the
> > previous message:
> >
> > <message id="3" type="addendum" from="bar at media" to="foo at media">
> >    <x xmlns="jabber:x:addendum">
> >       <append id="1">
> >          See also http://somepage.com/ for more details.
> >       </append>
> >    </x>
> > </message>
> >
> > That way, the <append> tag's "id" attribute can be uniquesly associated
> > with a particular mesage bar at media has already sent to foo at media.
>
> Thanks!
>
> Yes, this is precisely the kind of thing i'm looking for.  I also need the
> ability to refer to the reply that foo sends, and I can't really figure
> out how to do this without some non-standard crutch.
>
> Maybe a rough ascii diagram helps.
>
   [...snip...]

Sean-

I think you are struggling to find a solution to a problem that doesn't
really exist. Since all Jabber messages arrive in order (at least with
current server implementations), there is no need to know explicitly that
a user sends two messages as a reply to a single message from the other
end. It is implicit that if a message is sent by bar to foo, and then foo
sends two responses on the same <thread>, they are obviously "replying" to
the original message by bar. In addition, id numbers used in most clients
don't relate directly to conversations. Most client libraries will simply
increase the value of the id each time a packet is sent. id's are
generally not intended for this purpose. In fact, there is no guarantee
that other clients will behave in the way you have described, and I would
even go so far as to venture a guess that very few currently do.

For example, considering the following exchange:

1) foo sends a message to bar with id='1'
2) bar replies to message from foo without an id
3) foo sends an iq request in iq:register to component x with id='2'
4) foo replies to message from bar with id='3'
5) component x sends iq result to foo with id='2'
6) bar replies to message from foo without an id

... etc.

You'll notice that bar does not use id's in its message packets. This
behavior can be expected, because it is considered an optional attribute
in the spec. (see: http://jabber.org/ietf/draft-miller-xmpp-core-00.txt)

Basically, for the purposes of message threading, the <thread> element is
the appropriate feature of the protocol to use. If this is insufficient
for your needs, I suggest you look at JEP-0033. While this JEP is still
experimental, it would provide you with the functionality you need and
would save you from trying to overload another feature of the protocol,
which could cause incompatibilities and issues with some clients.

See JEP-0033: http://jabber.org/jeps/jep-0033.html

Cheers,

bs.