[RTW] Including or excluding an establishment protocol (Re: [dispatch] The charter formerly know as RTC-WEB take 3)

[Harald Alvestrand]

Changing the subject as is my habit.... forgive the introductory 
philosophical distraction.

I tend to look at success criteria, and if we need to achieve something 
to achieve success.

If we fail unless we do this work, it MUST be done.
If we can succeed without doing this work, it does not have to be done.
If we can succeed only if someone else does this work, we need to make 
sure that other thing also gets done (the classical example here is 
Javascript APIs for the functions we make available).

In this case, I define success (for myself - YMMV) as "browsers ship 
with well defined, usable functionality that allows audio and video 
communication between applications running as web pages in those 
browsers". More functionality (including legacy device interoperability 
with gateways only in the signalling path) is nice to have, but not 
essential for me to decide that we have succeeded.

The charter is a description of what work is to be done in this WG of 
the IETF.

If the IETF includes a signalling stack in the specification, it helps 
achieve the goal. But it's not essential, because those bits go across a 
wire that (likely) points in the direction of webservers that the pages 
load from, and those webservers can do signalling intermediation as needed.

What IS essential is that the semantics (not the syntax) of the 
information needed to establish the connections between the browsers is 
known and documented - because otherwise, the goal can't be achieved.

I'd be happy if the charter defined somewhat weaselly words like 
"Describe the information that must be exchanged between the endpoints 
in order to establish connectivity, and optionally describe how this 
information can be represented using existing signalling protocols".

But I wouldn't be happy with a charter that said "put SIP or XMPP in the 
browser". It's not necessary for success, so I don't want to be bound to 
doing it.

On 01/27/11 10:08, Henry Sinnreich wrote:
>> I believe
>> Jingle is more monolithic and easier to handle in this sense.)
> This adds even more to the endless discussions of SIP vs. Jingle, actually
> it also adds a 3rd option and folks who have implemented SIP/SIMPLE may or
> may not be happy about it.
>
> Bottom line:
> Adding a 3rd option to the signaling will bog down the RTC-Web work even
> more. The API should be a separate effort.
> Oh, the discussions there...
> Don't expect anyone there to give in easily :-), and why can/should they?
>
> Let's leave the API out for scope.
>
> Thanks, Henry
>
>
>
> On 1/27/11 10:15 AM, "Markus.Isomaki at nokia.com"<Markus.Isomaki at nokia.com>
> wrote:
>
>> Hi,
>>
>> Adam Roach wrote:
>>> On 1/26/11 8:04 PM, Cullen Jennings wrote:
>>>> Perhaps the charter should explicitly say this but that is why it
>>> seems so mute on this topic, it is.
>>>
>>> I would imagine something along these lines would put the topic to rest:
>>> "The selection, design and/or extension of a protocol or protocols for
>>> establishing and controlling media sessions is in scope for the working
>>> group."
>>>
>>> I think it's a lot better than remaining silent on the topic, since it
>>> leaves several avenues open to the working group. We really don't want
>>> to get part of the way down this path with people under the
>>> misimpression that we *must* design a new protocol, or that we *must*
>>> select an existing protocol. I think we should do whichever of these
>>> makes the most sense after a careful analysis, and that such analysis is
>>> best performed by the working group (not in DISPATCH).
>>>
>> I think the question at this point is that what aspects of the media session
>> establishment and control *need* to be standardized. Some people think that we
>> have to either pick a concrete protocol like SIP/SDP or XMPP/Jingle or design
>> something new but similar on top of HTTP or WebSocket. Other people seem to
>> think that most of this should actually be outside the scope of the charter,
>> and it is enough that we just standardize the media transport related
>> "enablers" within the browser. Each application/service could then pick/design
>> its own method of establishing the media sessions, on top of HTTP or
>> WebSocket.
>>
>> The first option (choose/design a single common protocol) would have at least
>> four main advantages:
>> 1. There would be no need to re-invent it for each service
>> 2. Inter-service/domain interoperability would be more straightforward
>> 3. Interconnect to SIP/PSTN/Jingle services would be more straightforward
>> 4. The service provider could buy/download and use an existing SIP or XMPP
>> server
>>
>> (The concrete problem with SIP would be, as we are aware of, that it would not
>> suffice to just declare that we use SIP, but we would have to do a lot of
>> profiling within SIP/SDP itself to ensure enough interoperability. I believe
>> Jingle is more monolithic and easier to handle in this sense.)
>>
>> The more liberal approach (let anyone do their own protocol) would probably be
>> easier to get done in IETF, and would still allow service providers to get
>> their services working across browsers. The need for reinventing a protocol
>> for each service could perhaps be mitigated by reusing JavaScript libraries (a
>> la Comet stuff today). Inter-domain/service interop would happen via SIP/XMPP
>> gateways (but end-to-end media could be a challenge). What I worry a bit in
>> this approach is that it might mean that only big/resourceful service
>> providers who know a lot about the technical stuff could build services, while
>> the ones with perhaps innovative services but little technical clue could be
>> left behind (which the big providers present in this work would not
>> necessarily mind). But I don't really know how the service provider scene
>> would be with the browser RTC. From a device/browser vendor perspective my
>> goal would be to make service creation and deployment as easy as possible.
>>
>> I would see this as a bottom up approach that we should first focus on the
>> media transport and NAT traversal issues that everyone agrees are needed, and
>> as those start to shape up, look at the session establishment needs. It could
>> be a phased approach that the browsers first only implement the media support
>> and may add a common setup protocol later on based on the need.
>>
>> Markus
>> _______________________________________________
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>> dispatch at ietf.org
>> https://www.ietf.org/mailman/listinfo/dispatch
>
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