[GRASS-user] .gislock problem

GRASS GRASS user
1

Hi guys,

I am a colleague of Jessica who posted before this: http://www.nabble.com/GRASS-BATCH-JOBS-to17470510.html#a17475609

We are using GRASS in an interactive website to calculate on-the-fly maps which are then presented to the user. It is not really a WebGIS-Client and it doesn’t aim to be one. We tested also pyWPS but the script was there before and it was to complicated to adept the needs of pyWPS.

As we are running GRASS in a “multiuser” web environment we need a workaround to treat different contemporary users. We decided then to create a bash workaround to solve this:

First we encountered that GRASS in batchmode is not writing the .gislock file, but it writes in normal interactive mode with the same user used.

In the next step we tested if we can then run two instances of the same script in the same mapset and it worked.

We can not find the issue why this is working. Currently we are in the testing phase and the project will be online soon, so we have to be sure what GRASS is doing with .gislock and all related staff to avoid problems with concurrent users.

Currently we are using Ubuntu 7.04 with packages of Jachym (GRASS 6.2). These will be updated to Hardy and GRASS 6.3 before release.

Any ideas?

Thanks in advance,

Christian

Dipl. Geogr. Christian Braun
Tel: +352- 425991-608
Mobil: +49-179-6845896
Mail: christian.braun@tudor.lu

*** www.crte.lu ***

Resource Centre for Environmental Technologies,
Public Research Centre Henri Tudor,
Technoport Schlassgoart,
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P.O. BOX 144,
L-4002 Esch-sur-Alzette, Luxembourg

2

Christian Braun wrote:

I am a colleague of Jessica who posted before this:
http://www.nabble.com/GRASS-BATCH-JOBS-to17470510.html#a17475609

We are using GRASS in an interactive website to calculate on-the-fly maps
which are then presented to the user. It is not really a WebGIS-Client and
it doesn't aim to be one. We tested also pyWPS but the script was there
before and it was to complicated to adept the needs of pyWPS.

As we are running GRASS in a "multiuser" web environment we need a
workaround to treat different contemporary users. We decided then to create
a bash workaround to solve this:
First we encountered that GRASS in batchmode is not writing the .gislock
file, but it writes in normal interactive mode with the same user used.
In the next step we tested if we can then run two instances of the same
script in the same mapset and it worked.

We can not find the issue why this is working. Currently we are in the
testing phase and the project will be online soon, so we have to be sure
what GRASS is doing with .gislock and all related staff to avoid problems
with concurrent users.

For a web application, I would suggest bypassing Init.sh altogether,
and setting any relevant environment variables yourself.

For non-interactive use, it should suffice to set:

  LD_LIBRARY_PATH
  PATH
  GISBASE
  GISRC
  GRASS_MESSAGE_FORMAT=silent
  GRASS_PAGER=cat

--
Glynn Clements <glynn@gclements.plus.com>