Thanks for this summary because I've been reading these sections of RFC
3921 *a lot* and there are so many different combinations that I lose it
quickly.
/me pokes psa too. A diagram of all the different interactions would go
a long way /me thinks
- Sylvain
Mridul Muralidharan a écrit :
Hi,
I think Peter is in the process of clarifying the bis spec on the
subscription appendix's. /me pokes psa :)
It might be a good idea to wait for that to be complete ... currently,
the state of specs is a bit icky from an impl point of view (though
well defined).
Roughly, 3921 says these :
- a user can add any contact to his roster, this does not trigger a
presence subscription request - but a roster push(*) will occur.
- a user can ask for subscription to contact : (if contact is not in
the user's roster (step 1 omitted), it gets automatically added) this
triggers a roster push(*) with change in subscription status (ask
attribute).
- if contact is online, subscribe is pushed to all available resources
using rules similar to roster push(*).
- if contact is offline or no resource is available which satisfies
rule for roster push(*), this is stored for later delivery.
- if contact rejects subscription (unsubscribed), this triggers a
roster update in user's roster appropriately (must not result in
removal of entry - I see that some servers remove the contact's jid
from user roster) and a corresponding roster push(*).
- 3921 says that the unsubscribed must be delivered to the user's
resources(*).
(*) The roster push above will happen only to all resources which have
requested (or modified) roster in some way (including asking for
subscription).
Similar steps above when contact's approves subscription.
The state table related to inbound unsubscribe, unsubscribed and
subscribed could be changed for 3921 bis spec (it has already been
changed for subscribed). If I am not wrong, the last step above would
not happen - that is, unsubscribe(d) will not be routed to the user.
Here, I assumed that there is no subscription between user & contact,
if that is present, it just adds more to the flow - refer to section 9
in 3921 [1]
Hope this clarifies. The steps above are the same irrespective of
whether it is a local contact, s2s contact, clustered configuration or
other combinations.
Regards,
Mridul
[1] http://www.xmpp.org/rfcs/rfc3921.html#substates
Tran Thai Son wrote:
Hi all,
I am writing a client and I've experienced different behaviors from
different servers in handling client's actions such as add / accept /
deny subscription requests. What surprised me is that it seems there
is no standard behaviors ( e.g. processes of treating actions, order
of notification messages pushing to the clients...) for the server.
E.g.:
- ejabbered 1.1.3 always adds the incoming contact to the user's
roster (with the subscription status = 0, means no relationship)
before pushing the subscription (add-friend) request to the user. So
the client gets two messages: one to notify that there is an item
added, the next to notify that there is a subscription request.
- meanwhile, openFire 3.3.1 does not add the contact before, so you
get only the later message. One (probably) bug I found: even when the
client sent a message denying the subscription request, the server
still adds the contact to the user's roster (with subscription= 0)
Furthermore, with the same actions from the clients, the number and
order of messages that the servers send significantly different.
E.g.
- ejabbered 1.1.3 tends to not to send any message to the contact
with subscription = 0. Example: If user B denied a subscription
request from user B (means no relationship at the moment), B will not
receive the next unsubscription request from A, but with openFire
3.3.1, it will.
- Furthermore, I found the order of messages that openFire pushes to
the clients rather annoying. For example, if user A removes user B
from its roster (and therefore B will also remove A - my
implementation), A will receive "unsubscribed" and "unsubscribe"
(respectively) from B before received the notification that its
removal was done. So you cannot trust that: when you remove a contact
from your roster, you won't receive unexpected message from that
contact; You also see that contact still in your roster for a while
(with subscription = 0).
Does any body experience similar problems ?
Son.
