Subject: [Simple] BIND and relays documentation

From: "Miguel A. Garcia" <[email-masked]>
Date: Mon, 24 Nov 2003 20:47:53 +0200

Hi:

A question about the recent decision to split the MSRP protocol into a 
relay-less document and a document that details the use of relays.

I would like to understand if the idea is to document the BIND primitive 
in the relay-less document or in the relayful document.

Some folks may argue that the BIND primitive is only used in the case 
there are relays in the path, and as such, it should be documented in 
the relays document. However, in doing so, we may risk that end points 
will not implement the BIND primitive ever, and therefore will not 
support the operation through relays.

I am in favour of documenting the BIND primitive in the core MSRP 
document, in spite that the relay operation will be described in the 
relays document.

Is this something that the working group is thinking?

/Miguel
-- 
Miguel-Angel Garcia                     Oy LM Ericsson AB
                                         Jorvas, Finland
mailto:[email-masked]     Phone:  +358 9 299 3553
mailto:[email-masked]        Mobile: +358 40 514 0002

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From: Ben Campbell <[email-masked]>
Date: Mon, 24 Nov 2003 12:54:40 -0600

My intent was that the BIND primative, or something simular, would be 
part of the relay specification.

For BIND to be useful, an endpoint must be aware that it wants to use a 
relay, and roughly how it should interact with the relay. It is not 
clear to me how we could specify those things generically in the base 
spec if relays are not documented there. It seems like we must treat 
relays either as an extension to the base spec, or as a lower layer that 
MSRP can run on. In either case, in order to choose to use a relay, an 
MSRP endpoint will require knowlege of the relay specification.

---

From: Ben Campbell <[email-masked]>
Date: Mon, 24 Nov 2003 12:54:40 -0600

---

From: "Miguel A. Garcia" <[email-masked]>
Date: Mon, 24 Nov 2003 21:57:40 +0200

I don't think  I really agree. An endpoint that is configured to use a 
relay needs to know that it has to start the session by getting the MSRP 
URI from the relay itself, with a BIND primitive. Then it needs to know 
that the URI it got is the one he populates in the SDP. What is 
happening at the other side of the relay is of no interest for the 
endpoint, and I believe this is what should be documented in the MSRP 
relay document.

Or is there something else the endoint must be aware of (for using a relay)?

/Miguel

Ben Campbell wrote:

>> I would like to understand if the idea is to document the BIND 
>> primitive in the relay-less document or in the relayful document.
>>

---

From: "Miguel A. Garcia" <[email-masked]>
Date: Mon, 24 Nov 2003 21:57:40 +0200

/Miguel

---

From: Ben Campbell <[email-masked]>
Date: Mon, 24 Nov 2003 14:03:52 -0600

Miguel A. Garcia wrote:

> that the URI it got is the one he populates in the SDP. 

That is exactly the knowledge I was talking about. Additionally, it has 
to know that relays are even possible to start out with, which implies 
knowledge of the relay specification.

My understanding of the mandate to remove relays from the base spec is 
that an endpoint that implements the base spec, and not the relay 
extension, does not know that relays even exist. Furthermore, until we 
complete the relay specification, we cannot know exactly how BIND should 
work. I don't think we can put a constraint on the relay specification 
that prevents it from changing the way you request a relay.

What is
>> For BIND to be useful, an endpoint must be aware that it wants to use 
>> a relay, and roughly how it should interact with the relay. It is not 
>> relays either as an extension to the base spec, or as a lower layer 
>> that MSRP can run on. In either case, in order to choose to use a 
>> relay, an MSRP endpoint will require knowlege of the relay specification.
>>
>>
>>
>> Miguel A. Garcia wrote:
>>
>>> Hi:
>>>
>>> A question about the recent decision to split the MSRP protocol into 
>>> a relay-less document and a document that details the use of relays.
>>>
>>> the relays document. However, in doing so, we may risk that end 
>>> points will not implement the BIND primitive ever, and therefore will 
>>> not support the operation through relays.
>>>

---

From: Ben Campbell <[email-masked]>
Date: Mon, 24 Nov 2003 14:03:52 -0600

What is

---

From: "Miguel A. Garcia" <[email-masked]>
Date: Tue, 25 Nov 2003 11:41:05 +0200

Inline.

Ben Campbell wrote:

>> relay needs to know that it has to start the session by getting the 
>> MSRP URI from the relay itself, with a BIND primitive. Then it needs 
>> to know that the URI it got is the one he populates in the SDP. 
> 
> 

The relays that are possible are not dependent on the use of BIND. It is 
just a matter of configuration, it does not affect the procedures. The 
UE will send a BIND in the same manner to the relay, providing that it 
knows (configured with) the relay address.

> that prevents it from changing the way you request a relay.

Maybe I have a missunderstanding here, but as far as I understand from 
the SIMPLE minutes, the problem with relays lies in the relay-to-relay 
communication, because if the issues already discussed in the list with 
multiplexing and head of line blocking. As far as I understand, the 
problem does not affect the endpoint-to-relay session (does it?).

What I am trying to avoid is that there are implementations of MSRP that 
will not support relays. It would be similar to not describing proxies 
in RFC 2616, and therefore, having web browsers that do not support proxies.

/Miguel

---

From: "Miguel A. Garcia" <[email-masked]>
Date: Tue, 25 Nov 2003 11:41:05 +0200

Inline.

/Miguel

---

From: Ben Campbell <[email-masked]>
Date: Tue, 25 Nov 2003 09:29:37 -0600

Miguel A. Garcia wrote:

> Inline.
> 
> 
> Ben Campbell wrote:
> 
>> Miguel A. Garcia wrote:
>>
>>> I don't think  I really agree. An endpoint that is configured to use 
>>> a relay needs to know that it has to start the session by getting the 
>> That is exactly the knowledge I was talking about. Additionally, it 
>> has to know that relays are even possible to start out with, which 
>> implies knowledge of the relay specification.
> 
> 
>> complete the relay specification, we cannot know exactly how BIND 
>> should work. I don't think we can put a constraint on the relay 
>> specification that prevents it from changing the way you request a relay.
> 
> 

That is the most significant thing slowing down the specification of 
relays. But the hum was about removing relays from the base spec entirely.

> in RFC 2616, and therefore, having web browsers that do not support 

I agree that would be nice, but as a practical matter, we don't want to 
make the base spec wait on getting all relay issues ironed out. It is 
not at all unlikely that changes to our previous thinking about how 
relays would work will change the way that an endpoint interacts with a 
relay. For example, changes in the inter-relay protocol may change what 
information has to be advertised in SDP and included in BIND or its 
equivilent.

I really do not see how we can specify how endpoints use relays when 
relays have not yet been specified.

---

From: Ben Campbell <[email-masked]>
Date: Tue, 25 Nov 2003 09:29:37 -0600