W3C home > Mailing lists > Public > xml-dist-app@w3.org > August 2006

Re: Constraints for multicast

From: Anish Karmarkar <Anish.Karmarkar@oracle.com>
Date: Wed, 30 Aug 2006 11:34:58 -0700
Message-ID: <44F5DA52.8020603@oracle.com>
To: David Hull <dmh@tibco.com>
CC: noah_mendelsohn@us.ibm.com, "xml-dist-app@w3.org" <xml-dist-app@w3.org>

I meant acknowledging it.

For example, the only difference between IP multicast and a IP unicast 
(from a sender's viewpoint) is that IP multicast address is a separate 
class D address (range: -


David Hull wrote:
> I'm not entirely clear what "modeling multicast explicitly" means.
> If it means acknowledging that multicast can happen, i.e., that a single 
> act of sending a message can result in multiple acts of receiving the 
> same message, then I don't see how we can avoid this and still produce 
> useful bindings for several transports of interest.  Since it appears by 
> example that we /can/ produce a useful binding with such acknowledgment 
> (in the English sense, not the protocol geek sense!) in the MEP, and no 
> one has given anything concrete about how we might proceed without it, 
> I'd say this point is pretty clear-cut by now.
> If it means trying to talk about things like how one might join a 
> multicast group, or how a binding might do fan-out or use network-level 
> broadcast or whatever, then of course not.  That would complicate the 
> architecture to no end and for no gain, and I would be strongly against it.
> Anish Karmarkar wrote:
>> noah_mendelsohn@us.ibm.com wrote:
>>> David Hull writes:
>>>> "The proposal to allow multicast suggests that the API might need to
>>>> allow multiple addresses."  This is certainly not the intent of the 
>>>> proposed text.  To take an example, if I send email to {dmh@tibco.
>>>> com, noah_mendelsohn@us.ibm.com}, that would be two instances of the
>>>> MEP.  If I send email to {xml-dist-app@w3.org}, that would be one 
>>>> instance, just as if I sent to {dmh@tibco.com}.  In other words, 
>>>> there is exactly one ImmediateDestination per MEP instance, just as 
>>>> the table says.
>>> When I send an email to a local distribution list (e.g. to: 
>>> xml-interest or some such) it's not uncommon for my mailer to pop up 
>>> a warning in the spirit of the following, one I would never see in 
>>> sending to an individual:
>>>         Warning: email addresses BobSmith, MaryJones, TommySlim not 
>>> found, continue sending to the other 53 users on this list?
>> Isn't this a binding specific error?
>> One could get a simliar error when sending an email to an address 
>> which is not a mailing list (without the question about 'continue 
>> sending'). Since we are really talking about fire-and-forget, I don't 
>> think these errors or warnings have a relevance at the MEP-level.
>> I do share Noah's concern about feature-creep and finishing up our 
>> one-way MEP work. I would prefer that our one-way MEP allow folks to 
>> use it for multicast (our MEP spec should not prevent it), but we 
>> shouldn't go into modeling it explicitly.
>> -Anish
>> -- 
>> <snip/>
Received on Wednesday, 30 August 2006 18:36:29 UTC

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