Subject: [MMUSIC] OPTIONS method in RTSP. Is it required or not in minimal client and server implementations?

From: [email-masked]
Date: Wed, 10 Jul 2002 15:30:03 +0300

Hello,
 
I have a question related to the RTSP OPTIONS method.
In the latest draft of RTSP RFC and also in the RFC 2326, in Table 2, OPTIONS method requirement is listed as follows:
 
 method            direction        object     requirement
 
OPTIONS           C->S, S->C       P,S        required  (S->C: optional)
 
In the Annex D.1 , minimal RTSP Client implementation, OPTIONS method is not included to the list of methods which MUST be implemented. 
 
So, My question is: How should this be interpreted? According to Table 2, OPTIONS method looks like to be mandated at least in the C->S direction. But this seems to conflict with the minimal implementation. If Table.2 does not apply to the minimal implementation, how should Table 2 be interpreted? I would really appreciate if this could be clarified.
 
I would also like to point out the usefulness of OPTIONS, especially for checking the 'session aliveness' according to the latest draft...
 
BR
Emre

Emre Baris Aksu
Senior Design Engineer

Nokia Mobile Phones
Tampere / Finland
e-mail : [email-masked]
Mobile : +358 40 743 1972
Fax    : +358 7180 70504

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From: Magnus Westerlund <[email-masked]>
Date: Wed, 10 Jul 2002 16:10:16 +0200

Hi Emre,

Table 2 is actually rather unclear regarding the requirement levels. It 
does not specify which entity the requirements concern. If you would 
read both the clients and the server minimal implementation requirements 
you would find a difference. The server is required to implement the 
options method while the client is not.

So follow annex D and be aware that the table is incomplete. It is 
necessary to do something about it.

I agree that options is very useful and all clients are recommended to 
implement it. I would say that options is the third or fourth variant of 
doing keep alive on my list after RTCP and PING and in hard combat with 
SET_PARAMETER. It main purpose however is capability discovery.

Regards

Magnus

-- 

Magnus Westerlund 

Multimedia Technologies, Ericsson Research ERA/TVA/A
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