Subject: [MMUSIC] RTSP: State machine

From: Geetha Srikantan <[email-masked]>
Date: Wed, 10 Sep 2003 17:41:06 -0700

A few of items to clarify about the state machine in
draft-ietf-mmusic-rfc2326bis-04.txt.

Page 112, Table 8:
In Ready-nm state, a SETUP request that is redirected resets the state
to Init. Does this imply
all session related resources and parameters are gone?

In Ready-nm state, when (a) RedP is reached, or (b) Server sends
redirect to client
without the Range header, does it mean that the server can teardown the
session?

Page 113, Table 10:
PAUSE for Range>now and Range <= now have the same effect of setting
PP to whatever is
specified in the Range header, right? If so, why are they specified
separately?

'End of Range' - what does this mean? How is it different from 'End of
Media'?

SETUP - the 4th case - needs tighter specifications, as noted in
previous email.

Finally, a general suggestion about the tables in this section - the
Response column includes
the response from the server and actions that the server would perform,
beyond sending
a response. I am wondering if there was a reason to combine these, and
if it might help to
instead maintain two tables - Response and PostCondition, say.

thanks
geetha

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---

From: Magnus Westerlund <[email-masked]>
Date: Thu, 11 Sep 2003 14:27:46 +0200

Hi

> all session related resources and parameters are gone?

Yes, I would think so. The Ready-nm state is kind of an add on, that was 
a result of some complaints 1.5 years ago about the situation that the 
server in some cases will first remove resources then to re-create them. 
However I have lately been questioning how wise this proposal is. I 
would in fact like to remove the Ready-nm state.

See the following bug:
https://sourceforge.net/tracker/?func=detail&atid=377744&aid=795295&group_id=23194

for some further input on this.

> without the Range header, does it mean that the server can teardown the

Yes, the intention was that.

> specified in the Range header, right? If so, why are they specified

No, they are not the same. Copied from the table:

PAUSE          PrsURL,Range>now     Play     Set RP & PP to given point
PAUSE          PrsURL,Range<=now    Ready    Set RP to Range Hdr.

Pause with a range header specifying a point not yet played out, sets 
the pause point and resume point. This is the point where the media 
delivery will be halted.

While for a pause with a range specifying a point in the past, will 
immediately be paused. However as the intention was to pause at the 
given point, the pause point is set to that given point.

> 'End of Range' - what does this mean? How is it different from 'End of

End of range is the last point in the Range header part of the PLAY 
request. For example if one ask one to play "npt=0-20" the end of range 
would be 20.

> SETUP - the 4th case - needs tighter specifications, as noted in

Ok

> instead maintain two tables - Response and PostCondition, say.

No reason, that other than I don't want to have two tables which 
otherwise are identical. If the where room I think one could put it into 
two columns. An alternative would be to move the comments into a 
referenced list to make it possible to fit into the page width.

Cheers

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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