[jdev] Different behaviors of ejabbered and openFire in pushing messages to the client!

[Mridul Muralidharan]

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.
> 
> 
>