UWS 1.1 job list, sorting NULL values

[Kristin Riebe]

Dear Grid members,

sorry to bother the list again with issues on UWS 1.1, but I think this
may be of interest for a number of people:

How are NULL values in datetimes to be treated when sorting?
(Is there an agreement on this within the IVOA?)

UWS 1.1 introduces filtering for the most recent jobs (LAST-keyword) or
for jobs started after a certain date-time (AFTER keyword). This refers
to the startTime for each job, see 2.2.2.1 Job list in
http://www.ivoa.net/documents/UWS/20150907/PR-UWS-1.1-20150907.pdf (page
13).

For pending jobs, in our UWS service at AIP, we set the startTime to
NULL or Nil in xml:
<uws:startTime xsi:nil="true"/>

(And some of our jobs in ERROR/ABORTED phase can also have no startTime
since they never started.)

Now, how are these to be treated when sorting? Should they be added at
the beginning or the end when sorting by increasing startTime? Or would
it make more sense to introduce a "createTime" and sort by this?

Did anyone finish including AFTER and LAST in their UWS 1.1
implementations, yet? How are you handling this?

Cheers,

Kristin

-- 
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Dr. Kristin Riebe
E-Science & GAVO

Email: kriebe at aip.de
Phone: +49 331 7499-377
Room:  B6/25
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Leibniz-Institut für Astrophysik Potsdam (AIP)
An der Sternwarte 16, D-14482 Potsdam
Vorstand: Prof. Dr. Matthias Steinmetz, Matthias Winker
Stiftung bürgerlichen Rechts
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