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Ray, Timothy J. (GSFC-583.0) wrote:
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<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">Scott,</span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">Ok. I think
I understand your
idea. What follows is an attempt to describe it in my own words (boy,
it’s
much easier to implement something than to specify it!).</span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">With regard
to the heartbeat cycle, a node
can be thought of as having 3 states:</span></font></p>
<ul style="margin-top: 0in;" type="disc">
<li class="MsoNormal" style="color: navy;"><font color="navy"
face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Registered – For each
heartbeat-cycle, the node sends a heartbeat and checks to see if a
heartbeat was received. If the incoming heartbeat is missed for N6
consecutive heartbeat-cycles, then the registrar’s death is imputed and
the state changes to ‘reconnecting’.</span></font></li>
<li class="MsoNormal" style="color: navy;"><font color="navy"
face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Reconnecting – For each
heartbeat-cycle, the node initiates a sequence of message exchanges
(AMS devotees know the details here – for example, send a
‘registrar-query’ to the server, receive a ‘cell-spec’ from the server,
send a ‘reconnect’ to the restarted registrar, ...) with outcomes that
fall into 3 categories. First, if “fully successful”, the node will
receive a ‘reconnected’ response from the restarted registrar (and
change state to ‘registered’). Second, if “fully unsuccessful”, the
node will receive a ‘you-are-dead’ response from the registrar, and
change state to ‘unregistered’. Third, all other possible outcomes
result in no change – i.e the ‘reconnect’ sequence will be initiated
again during the following hearbeat cycle.</span></font></li>
<li class="MsoNormal" style="color: navy;"><font color="navy"
face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Unregistered – This state
applies whenever the node is neither ‘registered’ nor ‘reconnecting’.
We can either say that there is no heartbeat-cycle while in this state,
or that there is a heartbeat cycle but no action is taken.</span></font></li>
</ul>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p class="MsoNormal"><font color="navy" face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial; color: navy;">How does
this line up with your thinking?</span></font></p>
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</blockquote>
I think this is a good way of putting it, Tim. I should think about it
a little more to convince myself that it covers all the edge cases, but
on first reading it looks right.<br>
<br>
Scott<br>
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