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Darren Everley wrote:
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<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Scott,<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">I am working here at
Scisys with Stuart Fowell on a
prototype implementation of AMS and have encountered something I would
like to
run past you.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">It is with regard to Node
Registration and in particular the
<i><span style="font-style: italic;">I_am_here </span></i> mpdu when
sent by
a Registrar. Hopefully my attempt at an explanation below is clear;<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Reading through the spec.
in section 4.2.5 where Node Registration
is detailed there are two possible implementation choices that can be
made; to
either extract information from the mpdus which are passed through the
Registrar
and then forward on these data in the appropriate situations, or do not
and
allow the Nodes to take care of this themselves after being introduced
to one
another.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">We are going with the
first choice and extracting
information as it is passed through the Registrar, hence using the <i><span
style="font-style: italic;">node_has_started</span></i> mpdu to notify
other
Nodes of a new Node starting. <o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">The way I read the spec.
is as follows;<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<ul style="margin-top: 0cm;" type="disc">
<li class="MsoNormal" style=""><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">New Node sends <i><span
style="font-style: italic;">node_registration</span></i> to Registrar<o:p></o:p></span></font></li>
</ul>
<p class="MsoNormal" style="margin-left: 18pt;"><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<ul style="margin-top: 0cm;" type="disc">
<li class="MsoNormal" style=""><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Registrar sends <i><span
style="font-style: italic;">you_are_in</span></i> to new Node<o:p></o:p></span></font></li>
</ul>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<ul style="margin-top: 0cm;" type="disc">
<li class="MsoNormal" style=""><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Registrar sends <i><span
style="font-style: italic;">I_am_here</span></i> to new Node
containing details of all other registered Nodes (mams endpoint,
delivery vectors, invitations, subscriptions, etc)<o:p></o:p></span></font></li>
</ul>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<ul style="margin-top: 0cm;" type="disc">
<li class="MsoNormal" style=""><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Registrar sends <i><span
style="font-style: italic;">node_has_started</span></i> on behalf of
the new Node to every other registered Node<o:p></o:p></span></font></li>
</ul>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal" style="margin-left: 18pt;"><font face="Arial"
size="2"><span style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<ul style="margin-top: 0cm;" type="disc">
<li class="MsoNormal" style=""><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">New Node sends <i><span
style="font-style: italic;">declaration</span></i> to each Node
identified within <i><span style="font-style: italic;">I_am_here</span></i><o:p></o:p></span></font></li>
</ul>
<p class="MsoNormal"><i><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; font-style: italic;"><o:p> </o:p></span></font></i></p>
<p class="MsoNormal"><i><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; font-style: italic;"><o:p> </o:p></span></font></i></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">The problem I have is
this; the <i><span style="font-style: italic;">I_am_here</span></i>
mpdu contains alongside a list of invitations and
subscriptions the delivery vectors for each Node. The way I am reading
the spec. it appears the delivery vector information is never passed to
the Registrar,
and therefore the Registrar cannot extract this from the mpdus to then
pass on
at a later date.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">The end result of this
would appear to be that when a new
Node registers the information provided to it will always contain zero
length
delivery vectors, and therefore no node will be able to communicate
with
another.<o:p></o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"><o:p> </o:p></span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">If I have missed
something glaringly obvious then I would
appreciate a pointer in the right direction.</span></font></p>
</div>
</blockquote>
Excellent catch, Darren, and it's a question that I think ought to go
to the Working Group for discussion.<br>
<br>
This is a vestige of the original design, in which the registering node
sent its own <i>I_am_starting</i> (via the registrar), its peers
always responded directly to it with their own <i>I_am_here</i>
messages containing their delivery vector lists, and the registering
node directly returned <i>declaration</i>s that contained its delivery
vector list -- the Registrar never had any need to see any delivery
vectors. But because the Registrar may now be responsible for getting
the delivery vectors out to the nodes in <i>I_am_here</i>, it now must
receive them.<br>
<br>
So I think we need to modify the spec in a couple of small ways:<br>
<br>
1. The <i>node_registration</i> message must now contain not only
the MAMS endpoint name but also the registering node's delivery vectors
list. This assures that the registrar has this information and can
pass it on in later <i>I_am_here</i> messages.<br>
<br>
2. But since the registrar now has this information and is the source
of all <i>I_am_starting</i>/<i>node_has_started</i> messages, why make
the registering node send its delivery vectors list again in subsequent
declaration messages? (And why make the new node's peers wait for
declarations before getting that information?) It's simpler and a
little more efficient to add delivery vectors list to <i>I_am_starting</i>
and <i>node_has_started</i>, and remove it from the declaration
structure.<br>
<br>
Anybody see anything wrong with this revision? If not, I'll post a
tweaked Red 2 in a couple of days.<br>
<br>
Scott<br>
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