Licallo/Visualization-session.md

-To open a session:
+
+**Warning:** access condition are likely to evolve other time to compensate for abuses and allow for a finer tuning of resources usage.
+
+## Presentation
+
+## Opening a session
+
+A session is opened by running a Slurm job through a script we provide: `/etc/slurm/jobvisu.slurm`. You need to specify a time (20mn in this example):
+
 ```
-$sbatch /etc/slurm/jobvisu.slurm
-sq
+11:55:35 [alainm@castor visu]# sbatch --time 0:20:0 /etc/slurm/jobvisu.slurm 
+Submitted batch job 18111816
+11:55:55 [alainm@castor visu]# squeue -u alainm
+             JOBID PARTITION     NAME     USER ST       TIME  NODES NODELIST(REASON)
+          18111816      visu TurboVNC   alainm  R       0:05      1 v001
+```
+When the session is started, a file is created in your home dir `~/.visu.<jobid>.out`, with the connection informations, including a `vnc_host` and a `password`:
+```
+11:56:01 [alainm@castor visu]# more ~/visu-18111816.out 
+account:   dsi
+username:  alainm
+hostname:  v001
+
+vnc_host:  v001:1
+password:  s5ZdRF0m
+11:56:17 [alainm@castor visu]# 
+```
+Here, the `vnc_host` tells us that a session is waiting for us on display 1 with password `s5ZdRF0m`.
+
+## Connecting from the client
+
+From your client machine, using your vnc client (here we use vncviewer), you can now connect to that session on the machine **visu.oca.eu**, on display 1:
+
+```
+alainm@jarvis:~$ vncviewer visu.oca.eu:1
+
+VNC Viewer Free Edition 4.1.1 for X - built Feb 25 2015 22:57:51
+Copyright (C) 2002-2005 RealVNC Ltd.
+See http://www.realvnc.com for information on VNC.
+
+Fri Aug 14 11:57:07 2020
+ CConn:       connected to host visu.oca.eu port 5901
+ CConnection: Server supports RFB protocol version 3.8
+ CConnection: Using RFB protocol version 3.8
+Password: >enter s5ZdRF0m< 
+Fri Aug 14 11:57:14 2020
+ TXImage:     Using default colormap and visual, TrueColor, depth 24.
+ CConn:       Using pixel format depth 6 (8bpp) rgb222
+ CConn:       Using ZRLE encoding
+
+```
+You will get a session on wich you can star an xterm and launch some stuff (here we try `/opt/VirtualGL/bin/glxspheres64`):
+
+![no-sphere](uploads/b304913b4f2dc30917420065088fd1c0/no-sphere.png)
+
+which produce:
+
+![spheres](uploads/6ef79e42a075c4491876a4a427e49628/spheres.png)
+
+## Closing the session
+
+Once you're done, de no forget to stop the session to allow other user to use the server:
+
+```
+12:12:18 [alainm@castor ~]# scancel 18111816
+12:12:23 [alainm@castor ~]# 
 ```
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