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Edell, David J. wrote:
<blockquote
cite="mid:FEEF8FE8A931BE478D2538A677C48BED046C45DF@aplesjustice.dom1.jhuapl.edu"
type="cite">
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<div dir="ltr" align="left"><span class="637121722-10092008"><font
color="#0000ff" face="Arial" size="2">Tim,</font></span></div>
<div dir="ltr" align="left"><span class="637121722-10092008"></span> </div>
<div dir="ltr" align="left"><span class="637121722-10092008"><font
color="#0000ff" face="Arial" size="2">Advanced filtering options could
have potential usage, and if I remember correctly are available to some
degree in the software bus of Goddard's cFE. I don't think its worth
the added processing costs to change to a string-based subject ID to
accomplish that though. </font></span></div>
<div dir="ltr" align="left"><span class="637121722-10092008"><font
color="#0000ff" face="Arial" size="2"><span class="637121722-10092008"></span></font></span> </div>
<div dir="ltr" align="left"><span class="637121722-10092008"><font
color="#0000ff" face="Arial" size="2"><span class="637121722-10092008"><font
color="#0000ff" face="Arial" size="2">At a minimum, there's always the
possibility of psuedo-filtering by specifying ranges of subject-IDs for
specific categories, which is sometimes done on its own to organize ID
listings. This becomes an implementation choice within a program
though, rather than a specification. </font></span></font></span></div>
<div dir="ltr" align="left"><span class="637121722-10092008"></span> </div>
<div dir="ltr" align="left"><span class="637121722-10092008"><font
color="#0000ff" face="Arial" size="2">I think the SubjectID, UnitID,
RoleID field combination is intended to give a similar effect in
combination with the "all subject" and "all role" subscription types.
It's been a while since I've looked at these field definitions though,
so I could be wrong. This might be another topic for discussion at
Berlin.</font></span></div>
</blockquote>
You're right, David, that's exactly what the "domain" concept in
subscriptions, announcements, etc. is all about.<br>
<br>
The problem here is that AMS is really intended to be for very high
performance (or, alternatively, for acceptable performance on highly
constrained hardware) in messaging, and string matching functions just
take a whole lot more processing time than integer comparison
functions; also, strings are typically a lot bigger than integers, so
they consume a lot more bandwidth -- not necessarily a big deal in
Earth orbiters, but a fairly big deal in deep space operations. So the
design decision to use numeric subject IDs rather than strings was
deliberate.<br>
<br>
At the same time, the question of supporting more powerful subject
matching capability does come up over and over again; most (maybe all)
commercial message-oriented middleware systems have it. The approach
we've been taking is to say that where these capabilities are needed
you presumably don't need high efficiency at the same time, so you can
afford an extra transmission hop, in which case the AMS Proxy
Architecture (section 6.1 of the spec) is the most flexible and
powerful way to provide this functionality. I believe CNES, in fact,
is already contemplating development of a prototype AMQP-based AMS
Proxy system.<br>
<br>
Scott<br>
<blockquote
cite="mid:FEEF8FE8A931BE478D2538A677C48BED046C45DF@aplesjustice.dom1.jhuapl.edu"
type="cite">
<div dir="ltr" align="left">
<hr tabindex="-1"></div>
<div dir="ltr" align="left"><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, September 10, 2008 6:15 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] better subject-matching?<br>
</font><br>
</div>
<div class="Section1">
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">Hello all,</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;">Does anyone see a
(worthwhile) benefit to enhancing our subject-matching capabilities to
allow hierarchical subject-ids and some pattern-matching? Subjects
would be transmitted as character strings rather than 2-byte numbers,
and subscribers would be able to specify some sort of
regular-expression format.</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;">For example, if there
were these subjects:</span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">
Attitude.sun_sensor</span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;">
Attitude.momentum_wheel</span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"> Attitude.gyros</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;">Then an application might
subscribe to attitude.* to receive all subjects within the
‘attitude’ domain.</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;">I don’t think this
enhancement is needed for the typical NASA/Goddard mission, nor are any
missions (that I’m aware of) asking for it. Still, it seems like
something worth considering. Does anyone have an opinion?</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;">Tim</span></font></p>
<p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size: 10pt; font-family: Arial;"></span></font> </p>
</div>
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</pre>
</blockquote>
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