Re: [ssm] Re: last call comments on ssm-arch doc

Hugh,

> SSM is particularly well-suited to dissemination-style applications with
> a single sender.  It can be used in multi-source applications, but the
> multi-source "rendezvous" functionality must be implemented by the
> application or by an application-layer library.  For instance, an
> application that desires to provide a secondary data source in case the
> primary source fails must implement the failover mechanism in the
> application itself, presumably by using two channels, as two hosts
> cannot both send to a single SSM channel.  SSM does not support network-
> layer multicast resource discovery.

I'm confusing the terminology (or definition) of "channel" now.

Let's imagine something like an application of a panel discussion.
E.g., now, there are two senders (S1 and S2) as the speakers, and then
we do ((S1,S2),G) join. In this case, does this panel discussion works
as "a single channel" application or "two channels" application?
This example can be similar case of using a whiteboard application. S1
and S2 write some words on a same whiteboard, and many receivers watch
it. In this application, do we say the receivers join "a single
channel" or "two channels"?

I've thought these answers would be "a single channel" since both S1
and S2 work for a same application, but your statements would make me
reform...
So, if each answer is "two channels", is it correct that a channel
MUST consist of a single source except such failover mechanism? Or,
are there any other applications that would prompt ((multiple Ss),G)
join for a single channel?
If the answer is "a single channel", then above statements might not
be fair enough for me. Especially, "but the multi-source "rendezvous"
functionality must be implemented by the application or by an
application-layer library." seems to be strange.

Thanks.
--
Hitoshi Asaeda
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