[Sip-implementors] SUBSCRIBE Question (RFC3265)

[David Stuart]

Hi All,

I was wondering, the RFC states that there can be multiple SUBSCRIBEs in
a Dialog. I'm just wondering in what situations this can happen.
Anything you can do to help, thanks.. :)

Dave

[Robert Sparks]

Some situations (not intended to be exhaustive):

- Subscribing to more than one event (You can subscribe to both
your presence and presence.winfo in the same dialog for example).
- Multiple REFERs inside an INVITE initiated dialog
- A REFER and an Event: dialog subscription inside an INVITE initiated
dialog.

RjS

Post by David Stuart
Hi All,
I was wondering, the RFC states that there can be multiple SUBSCRIBEs in
a Dialog. I'm just wondering in what situations this can happen.
Anything you can do to help, thanks.. :)
Dave

[David Stuart]

1) Still somewhat confused. I don't quite grok Event Templates as of
yet, so I'm not sure how this will result in an additional Dialog.

2) How does REFER affect SUBSCRIBE/NOTIFY?

3) This touches on another question of mine. If an INVITE Dialog is
already running, does a SUBSCRIBE still create a new (separate) Dialog,
or does it wedge into the INVITE Dialog?

Post by Robert Sparks
- Subscribing to more than one event (You can subscribe to both
your presence and presence.winfo in the same dialog for example).
- Multiple REFERs inside an INVITE initiated dialog
- A REFER and an Event: dialog subscription inside an INVITE initiated
dialog.
RjS

Post by David Stuart
Hi All,
I was wondering, the RFC states that there can be multiple SUBSCRIBEs in
a Dialog. I'm just wondering in what situations this can happen.
Anything you can do to help, thanks.. :)
Dave

[Robert Sparks]

Post by David Stuart
1) Still somewhat confused. I don't quite grok Event Templates as of
yet, so I'm not sure how this will result in an additional Dialog.

Well, to be more careful with the terminology (because there's a
little bit of a trap there), it results in an additional subscription
sharing a common dialog identifier.

Post by David Stuart
2) How does REFER affect SUBSCRIBE/NOTIFY?

REFER creates a subscription, the results are reported with NOTIFYs.
See RFC3515.

Post by David Stuart
3) This touches on another question of mine. If an INVITE Dialog is
already running, does a SUBSCRIBE still create a new (separate) Dialog,
or does it wedge into the INVITE Dialog?

It depends on whether you send the SUBSCRIBE using the same dialog
identifiers or not. You don't _have_ to. Several people are right
now because we don't have a better mechanism in place (yet) to
make sure a SUBSCRIBE on a different dialog ends up at the same
endpoint the INVITE did. Look in SIPPING for the current work on that
problem.

Post by David Stuart

Post by Robert Sparks
- Subscribing to more than one event (You can subscribe to both
your presence and presence.winfo in the same dialog for example).
- Multiple REFERs inside an INVITE initiated dialog
- A REFER and an Event: dialog subscription inside an INVITE initiated
dialog.
RjS

Post by David Stuart
Hi All,
I was wondering, the RFC states that there can be multiple SUBSCRIBEs in
a Dialog. I'm just wondering in what situations this can happen.
Anything you can do to help, thanks.. :)
Dave