Subject: [MMUSIC] RTSP: Keep-alive

From: Magnus Westerlund <[email-masked]>
Date: Tue, 12 Jul 2005 11:32:35 +0200

Hi,

Based on the decision to go with RTSP version 1.1. If we can ignore most 
backwardscompatibility issues when defining the protocol. Wouldn't it be 
better to reverse last years decision on removing PING?

The discussion from last year (San Diego):

1. Which keep-Alive mechanism to be normative to use?
   http://rtsp.org/bug992076

It was directly agree that there shall be normative text for:
A server SHALL update the keep-alive timer for any method which it 
provides a positive answer and contains a session header.
A client is RECOMMENDED to use method X for keep-alive when it has not 
other RTSP request to send.

Then we started discussing what that method X should be. The different 
arguments raised:
- There is desirable to have request and responses with minimal message 
sizes. This is especially important on low bandwidth links, like 
wireless (GSM GPRS, UMTS, CDMA2000).
- Some concern over the extra processing that results from the use of 
OPTIONS method, or other method that can't be totally stripped for the 
purpose.

- The concerns for OPTIONS was not major as currently used, however if 
used in relation to a specific media resource, and when the number of 
extensions grow, both processing and size will increase.

- Using something other than OPTIONS may reduce overloading.

- The extra implementation concern is minimal, as a server anyway need 
to do keep-alive on all methods.

- At the same time specifying a new method like PING does create some 
backwards compatibility issues.

The conclusion was:
a. To remove PING
b. to RECOMMEND SET_PARAMETER for keep-alive as the overloading is less 
and the request without headers and body clearly indicates keep-alive.
c. To document a backwards compatibility consideration, that using 
OPTIONS may be needed to use if server or client returns 501 (Not 
Implemented).

--- End of quote ---

Thus I don't see the backwards compatibility issue with Ping anymore!

Cheers

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
----------------------------------------------------------------------
Ericsson AB                | Phone +46 8 4048287
Torshamsgatan 23           | Fax   +46 8 7575550
S-164 80 Stockholm, Sweden | mailto: [email-masked]

_______________________________________________
mmusic mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/mmusic