Re: [bfcpbis] Alexey Melnikov's Discuss on draft-ietf-bfcpbis-sdp-ws-uri-08: (with DISCUSS and COMMENT)

[Alissa Cooper <[e-mail]>]

Hi Ram,

I had some further conversation with Alexey on the side and wanted to come back to a question he posed: is there a reason why a=ws-uri and a=wss-uri both need to be specified? Why can’t a single label be specified, say a=websocket-uri, and then have normative language requiring the scheme in the URI itself to match what’s in the associated m-line (ws:// for TCP/WS/BFCP and wss:// for TCP/WSS/BFCP)? Won’t it be more efficient for implementations to grab the URI itself anyway and check that the scheme matches the m-line?

Thanks,
Alissa

> On Jan 17, 2017, at 9:40 AM, Ram Mohan R (rmohanr) <[e-mail]> wrote:
> 
> Alissa,
> 
> I am fine with the proposed text.
> 
> Thanks,
> Ram
> 
> -----Original Message-----
> From: Alissa Cooper <[e-mail]>
> Date: Tuesday, 17 January 2017 at 8:07 PM
> To: Alexey Melnikov <[e-mail]>
> Cc: The IESG <[e-mail]>, "[e-mail]" <[e-mail]>, "[e-mail]" <[e-mail]>, "Charles Eckel (eckelcu)" <[e-mail]>, "[e-mail]" <[e-mail]>, "Ram Mohan R (rmohanr)" <[e-mail]>
> Subject: Re: [bfcpbis] Alexey Melnikov's Discuss on draft-ietf-bfcpbis-sdp-ws-uri-08: (with DISCUSS and COMMENT)
> 
>    Alexey, would the following changes clarify things?
> 
>    Section 4.1
>    OLD
>    the server side, which could be either
>       the offerer or answerer, MUST add an "a=ws-uri" or "a=wss-uri"
>       attribute in the media section
>    NEW
>    the server side, which could be either
>       the offerer or answerer, MUST add an "a=ws-uri" or "a=wss-uri”
>       attribute (but not both) in the media section
> 
>    Section 4.3
>    OLD
>    If the answers assigns SDP "setup" attribute with "passive", then it
>       MUST have a URI in either "a=ws-uri" or "a=wss-uri" attribute
>       depending on whether the application uses WebSocket or
>       secureWebSocket.
>    NEW
>    If the answers assigns SDP "setup" attribute with "passive", then it
>       MUST have a URI in either "a=ws-uri" or "a=wss-uri" attribute
>       (but not both) in the media section, depending on whether the application uses WebSocket or
>       secureWebSocket.
> 
>    Ram, would you be okay with those clarifications?
> 
>    Alissa
> 
> 
>> On Jan 16, 2017, at 10:09 AM, Ram Mohan R (rmohanr) <[e-mail]> wrote:
>> 
>> Hi Alexey,
>> 
>> -----Original Message-----
>> From: Alexey Melnikov <[e-mail]>
>> Date: Monday, 16 January 2017 at 8:25 PM
>> To: "Ram Mohan R (rmohanr)" <[e-mail]>, The IESG <[e-mail]>
>> Cc: "[e-mail]" <[e-mail]>, "[e-mail]" <[e-mail]>, "Charles Eckel (eckelcu)" <[e-mail]>, "[e-mail]" <[e-mail]>
>> Subject: Re: [bfcpbis] Alexey Melnikov's Discuss on draft-ietf-bfcpbis-sdp-ws-uri-08: (with DISCUSS and COMMENT)
>> 
>>   Hi Ram,
>> 
>>   On Mon, Jan 16, 2017, at 02:49 PM, Ram Mohan R (rmohanr) wrote:
>>> Hi Alexey,
>>> 
>>> Please see inline <Ram>
>>> 
>>> -----Original Message-----
>>> From: Alexey Melnikov <[e-mail]>
>>> Date: Monday, 16 January 2017 at 7:57 PM
>>> To: "Ram Mohan R (rmohanr)" <[e-mail]>, The IESG <[e-mail]>
>>> Cc: "[e-mail]"
>>> <[e-mail]>, "[e-mail]"
>>> <[e-mail]>, "Charles Eckel (eckelcu)" <[e-mail]>,
>>> "[e-mail]" <[e-mail]>
>>> Subject: Re: [bfcpbis] Alexey Melnikov's Discuss on
>>> draft-ietf-bfcpbis-sdp-ws-uri-08: (with DISCUSS and COMMENT)
>>> 
>>>   Hi Ram,
>>> 
>>>   On Mon, Jan 16, 2017, at 06:09 AM, Ram Mohan R (rmohanr) wrote:
>>>> Hi Alexey,
>>>> 
>>>> Thanks for your feedback. Please see inline <Ram>
>>>> 
>>>> -----Original Message-----
>>>> From: bfcpbis <[e-mail]> on behalf of Alexey Melnikov
>>>> <[e-mail]>
>>>> Date: Saturday, 14 January 2017 at 3:49 AM
>>>> To: The IESG <[e-mail]>
>>>> Cc: "[e-mail]"
>>>> <[e-mail]>, "[e-mail]"
>>>> <[e-mail]>, "Charles Eckel (eckelcu)" <[e-mail]>,
>>>> "[e-mail]" <[e-mail]>
>>>> Subject: [bfcpbis] Alexey Melnikov's Discuss on
>>>> draft-ietf-bfcpbis-sdp-ws-uri-08: (with DISCUSS and COMMENT)
>>>> 
>>>>   Alexey Melnikov has entered the following ballot position for
>>>>   draft-ietf-bfcpbis-sdp-ws-uri-08: Discuss
>>>> 
>>> 
>>>>   ----------------------------------------------------------------------
>>>>   DISCUSS:
>>>>   ----------------------------------------------------------------------
>>>> 
>>>>   This is generally a well written document, but I have a small list of
>>>>   issues that I would like to discuss before recommending its approval:
>>>> 
>>>>   1) Are a=ws-uri and a=wss-uri mutually exclusive? (Section 4.3 is a
>>>>   good
>>>>   place to mention what to do if both are specified).
>>>> 
>>>> <Ram> Yes kind of. In a given media line (m= line) we will either have
>>>> a=ws-uri or a=wss-uri. That said a response from a BFCP server using
>>>> webSocket as a transport can
>>>> have two media lines one with ws and other with wss. Something like:
>>>> 
>>>> Answer (server):
>>>>  m=application 50000 TCP/WSS/BFCP *
>>>>  a=setup:passive
>>>>  a=connection:new
>>>>  a=wss-uri:wss://bfcp-ws.example.com?token=3170449312
>>>>  m=application 50000 TCP/WS/BFCP *
>>>>  a=setup:passive
>>>>  a=connection:new
>>>>  a=ws-uri:ws://bfcp-ws.example.com?token=3170449312
>>> 
>>>   [Alexey]: This is exactly my problem, you should specify how a
>>>   recipient
>>>   should handle your example above. If you only have 1 attribute, the
>>>   problem goes away entirely.
>>> 
>>> <Ram> in the above case, they are still two different m= lines. The
>>> receiver (after offer/answer is done) of this SDP connects to the URI
>>> mentioned in that m= line. 
>>> Note I just re-used the same URL/port in the example above. If there are
>>> multiple m=application media lines (they will be for different
>>> applications) being negotiated in SDP, one application may use secure WS
>>> and other application may use non-secure WS. The client after it receives
>>> the answer SDP will just setup the connection to the URI specified in the
>>> attribute.  
>> 
>>   Sorry, I was thinking about different example:
>> 
>>   m=application 50000 TCP/WSS/BFCP *
>>      a=setup:passive
>>      a=connection:new
>>      a=wss-uri:wss://bfcp-ws.example.com?token=3170449312
>>      a=ws-uri:ws://bfcp-ws.example.com?token=3170449312
>> 
>>   You have 2 conflicting URIs for the same m= line. Is this possible?
>> 
>> <Ram> No this is not possible. If the transport is TCP/WSS/BFCP we should have only a=wss-uri. If transport is TCP/WS/BFCP we should have only a=ws-uri.
>> 
>> Regards,
>> Ram
>> 
>>> I don’t see any problem in here.  
>>> 
>>> Regards,
>>> Ram
>>> 
>>>>   Why not a single attribute, considering that both ws: and wss: URIs
>>>>   are
>>>>   possible?
>>>> 
>>>> <Ram> I would still prefer two attributes. We just followed the
>>>> convention / approach that was used in [RFC6455].  
>>> 
>>> 
>> 
>> 
> 
> 
>