troubles with VO apps in multiuser environment

[Petr Skoda]

Hi all

I have just finished several courses teaching VO technology and at one 
university (in Brno) the students were using central server with terminals 
under individual accounts.

We had  immediately seen that so far no one tried to use VO tool sin such 
environment as it did not work or behaved chaoticaly ....

I am addressing this to all VO apps developer in order to revise their 
soultion and identify the potential issues....

Case 1) VOspec
  version 6.6

we wanted to make simple use case - select theory servers, select Kurucza 
model - select range of Teff, logg make query and select say 3-5 spectra 
to display ....

The same version of VOspec did work on my  notebook but not to the 
students - from 8 anly one succeeded. My guess is below.
When you normally load spectrum (it writes e.g. 3 spectra retrieved) but 
the selected spectrum is highlighted red and nothing displays (normal way 
is highlighted green and displays).

After some investigation the trouble seems to be in temporary file
/tmp/vospec/cache.

The first usage on given computer creates this but then it belongs to the 
student who made it (he is owner of the dir) - others do not have 
permission to write there and so all other VOspec instances fail ....

So it would require create  temporary directory in users home - e.g. 
/home/user/tmp  instead of tmp ....

another issue is with java - most other apps like topcat or splat-vo 
worked seamlessly with openjava on linux ... VOspec did not show all 
theoretical services - only about 2 and complains on troubles with parsing 
of some votables .... it has it somehow precached the services and there 
seems not be 
way how to not parse them ....


2) Case SAMP


we tried to  activate web samp on Vizier web page (the sattelite dish that 
runs SAMP hub) and send table to TOPCAT.

Complete mess ....   some students were able to run it (I gues about first 
2 or 3) those who were late not - even with closing all windows and 
restarting ....

When clicking on dish it did not ask for authorization (famous SAMP 
window) and it did not show in hub registered apps.

Even worse when all 8 students tried to randomly close all windows with to 
tools and restart again and broadcast tables ....
it appeared that in fact some were sending their tables to other users - 
we did not find logic behind this ....
Some did not see Aladin web registered in their SAMP hub but were able 
seamlessly (withou noticing) to send tables to some other students - but 
the broadcasting did not work to all - only about 2 or 3...

When we did not try SAMP on web (namely in Vizier web) but SMAP hub etween 
SPLAT, TOPCAT and Aladin it seemed to work well..

I gues it may be again given by position of samp samp file who is owned 
only by someone .....

Can someone try other VO tools in multi user environment ?
IMHO it is crucial for success of VO education (in schools) but not only 
there .....

Best regards,

Petr

*************************************************************************
*  Petr Skoda                         Phone : +420-323-649201, ext. 361 *
*  Stellar Department                         +420-323-620361           *
*  Astronomical Institute AS CR       Fax   : +420-323-620250           *
*  251 65 Ondrejov                    e-mail: skoda at sunstel.asu.cas.cz  *
*  Czech Republic                                                       *
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