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<DIV dir=ltr align=left><SPAN class=948181017-10072008><FONT face=Arial
color=#0000ff size=2>opinion - the third alternative is good enough, because
...</FONT></SPAN></DIV>
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color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=948181017-10072008><FONT face=Arial
color=#0000ff size=2>When the Registrar doesn't get Heartbeat from the
Configuration server, Registrar will eventually re-try to do an
ANNOUNCE_REGISTRAR with its Unit Number. It will either be successfully
registered by the Configuration server, or rejected if another Registrar already
has that Unit Number - in which case our lonely Registrar should shut
down. Am I remembering it all right?</FONT></SPAN></DIV>
<DIV> </DIV><!-- Converted from text/plain format -->
<P><FONT size=2>Patrick Donahue<BR>(256) 544-5943 office<BR>(256) 721-0726
home<BR>(256) 682-9753 cell</FONT> </P>
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<FONT face=Tahoma size=2><B>From:</B> sis-ams-bounces@mailman.ccsds.org
[mailto:sis-ams-bounces@mailman.ccsds.org] <B>On Behalf Of </B>Scott
Burleigh<BR><B>Sent:</B> Thursday, July 10, 2008 11:53 AM<BR><B>To:</B>
sis-ams@mailman.ccsds.org<BR><B>Subject:</B> Re: [Sis-ams] minor
heartbeat-related issue<BR></FONT><BR></DIV>
<DIV></DIV>Edell, David J. wrote:
<BLOCKQUOTE
cite=mid:FEEF8FE8A931BE478D2538A677C48BED03D1F8F1@aplesjustice.dom1.jhuapl.edu
type="cite">
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<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=019115318-09072008>I ran into a similar issue when finishing my
implementation. </SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=019115318-09072008></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=019115318-09072008>I believe the intent was for the reply method to be
inferred from the transport service in that case--meaning that this is a
piece of data missing in the AMS content itself. In my case, I think
the node-id was included which I used in the absence of TS specified context
to infer the reply address in the APL implementation for unregistered nodes
(which uses a direct mapping). I don't remember if/how I had addressed this
for an unregistered registrar.</SPAN></FONT></DIV></BLOCKQUOTE>David's answer
is right, and I realize this may not be wholly satisfactory. There's an
implicit expectation that the receiving entity can figure out the MAMS
endpoint name of the sender in a transport-specific way that is left as an
implementation issue. For example, if you're using UDP as the transport
for MAMS traffic then when you receive the heartbeat you can get the IP
address and port number of the sending socket from the recvfrom() parameters
and send the you_are_dead message back to that socket. You'd have
similar information if you used, say, the DTN Bundle Protocol as your MAMS
transport protocol. This is one of the main reasons that TCP, for
example, is not a particularly good choice as a MAMS transport protocol: the
asymmetry of connect/accept makes this kind of echoing complex to
implement.<BR><BR>At minimum (I now realize), this implementation
responsibility ought to be made explicit somewhere -- probably in 4.2.7.4.4
and 4.2.7.4.5, although I guess a case could be made for documenting it in the
Green Book instead.<BR><BR>Alternatively, we could modify the heartbeat
message to carry MAMS endpoint name. I am not real comfortable with
this, as I think it would be perceived as adding a lot of bandwidth
consumption that would be needed only in two edge cases.<BR><BR>A third
alternative, though, might be simply to ditch the transmission of you_are_dead
messages in these cases, i.e., just ignore the heartbeats. The only
downside of this would be that the unregistered entity wouldn't receive such
prompt notification that it is not currently registered. But eventually
it would drop back into imputed termination logic and go through the relevant
re-registration procedure, so there's no real harm done.<BR><BR>On reflection,
I like this third alternative pretty well. What do you all
think?<BR><BR>Scott<BR>
<BLOCKQUOTE
cite=mid:FEEF8FE8A931BE478D2538A677C48BED03D1F8F1@aplesjustice.dom1.jhuapl.edu
type="cite">
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<FONT face=Tahoma size=2><B>From:</B> <A class=moz-txt-link-abbreviated
href="mailto:sis-ams-bounces@mailman.ccsds.org">sis-ams-bounces@mailman.ccsds.org</A>
[<A class=moz-txt-link-freetext
href="mailto:sis-ams-bounces@mailman.ccsds.org">mailto:sis-ams-bounces@mailman.ccsds.org</A>]
<B>On Behalf Of </B>Ray, Timothy J. (GSFC-583.0)<BR><B>Sent:</B> Wednesday,
July 09, 2008 2:51 PM<BR><B>To:</B> <A class=moz-txt-link-abbreviated
href="mailto:sis-ams@mailman.ccsds.org">sis-ams@mailman.ccsds.org</A><BR><B>Subject:</B>
[Sis-ams] minor heartbeat-related issue<BR></FONT><BR></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Dear WG
members,</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">(Scott: thanks for posting
the latest specs, and for keeping them up-to-date.)</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Here’s another issue that I’ve
run into. Perhaps I am missing something?</SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">4.2.7.4.4 - If a server receives a ‘heartbeat’ from
an unregistered registrar, it is supposed to send back a
‘you-are-dead’. In order to do that, it will need to know how to
contact the registrar (i.e. its mams-endpoint-name). That name is not
included in the ‘heartbeat’. How can a server send an MPDU to an
unregistered registrar?</SPAN></FONT></P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"></SPAN></FONT> </P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt">4.2.7.4.5 - Same as previous, but registrar receives
a heartbeat from an unregistered
node.</SPAN></FONT></P></DIV></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>