[Paraview] ParaviewWeb on EC2

claude claude at theweak.link
Fri Jan 20 10:33:39 EST 2017


Hi Sebastien,

sorry to make you dig into old memories :S
so far I have been able to achieve the goals thanks to the documentation
and help. Last thing I tried was to connect the visualizer to pv server
in parallel. The help contents (--help) of bin/pvserver and the
pvw-visualizer.py helped me to figure it out (all I had to do is use
"reverse connection" and have pvserver connect to paraviewweb).

I don't think it's possible to document every single possibility and
that's where the code quality+comment and built-in help are very useful
and complete. I will let you know if I find anything but so far so
amazingly good.


Regarding the EC2 at startup (pvw-start service running /data/start.sh),
only DNS_NAME (ec2-xxxx-compute1-amazonaws.com) is fetched and replaced
in the {apache/launcher}-TEMPLATE.{conf/json} files. I didn't see any
other variable in there.

After checking with JSONLint, the launcher JSON file is indeed valid.

Paying more attention to the network requests, I don't see the failed
GET and WS switching protocol requests anymore. Even more strange, when
I move the camera, I can see the stack of black/blank frames being send
by the server (axis are not visible either).

By the way I used this config:
* apache.conf
  RewriteCond %{QUERY_STRING} ^sessionId=(.*)&path=(.*)$ [NC]
  RewriteRule ^/proxy.*$ ws://${session-to-port:%1}/%2 [P]

* launcher.json
  "sessionURL" : "ws://DNS_NAME/proxy?sessionId=${id}&path=ws",

As I am writing this, I just restarted the instance (terminate+launch)
instead of reboot and it is now working... I went back to see the logs
of failed remote viewing and I can now see this at the very end (after
proper launching and everything):
XIO:  fatal IO error 0 (Success) on X server ":0.0"

So here is what I am guessing:
- I messed up something in the config files yesterday as I didn't get to
that point
- rebooting the instance doesn't start X properly, which fails to render
the 3D view and explains why the frames are blank but everything else is
fine.
- somehow re-launching the instance starts X properly.

I am puzzled but also happy that it seems to be working :)
Do you know what would be the reasons for this issue with X? Since I
started from the pv AMI, I didn't have to install any drivers nor
configure the display. Maybe I'll try a fresh AMI with ubuntu-16 and
install the drivers nvidia-367 to see if I encounter similar issues with X.

Thanks for the pointers Sebastien.

cheers,
Claude

On 01/19/2017 06:19 PM, Sebastien Jourdain wrote:
> Hi Claude,
>
> I'm glad you like our doc and code. If you feel we are missing
> something that is not obvious, please report it so we can fix it.
>
> Regarding your issue, you had a good reflex in fixing apache and the
> launcher config, as with PV5.2 we use a second ws connection for
> streaming the images in binary format. But it has been forever since I
> setup that ami, I have very little memory of what was setup.
>
> I do know that we use 'sed' to dynamically replace some string so the
> proper HOST for apache and the launcher get used, but I don't remember
> if it was DNS_NAME or something else. But from what I understand,
> you've done exactly what I would have done myself.
>
> I'm wondering if when you edited your launcher config you managed to
> produce an invalid JSON file. (You can paste it
> here http://jsonlint.com/ to be sure)
>
> Moreover, seeing the network calls of the web page that don't even
> load might be useful. I'd be curious to see the response of the POST
> on /paraview.
>
> Seb
>
>
> On Thu, Jan 19, 2017 at 5:01 PM, claude <claude at theweak.link
> <mailto:claude at theweak.link>> wrote:
>
>     Hello!
>
>     Following up one of the previous thread on setting up
>     ParaviewWeb+Visualizer, I am trying to get it going on AWS EC2 with
>     paraview-5.2. Maybe someone already went through it and know how to
>     solve this little problem?
>
>     * I launched the public AMI (ami-34f3f65e) on Ubuntu-14 with
>     paraviewweb
>     4.4 which seemed like a good starting point.
>     * I tested the visualizer on paraviewweb-4.4 and works perfectly.
>     * I downloaded paraviewweb-5.2 and updated the 'pv' and 'www' symlinks
>     under /data folder (see 'aws_data_dir' snapshot attached).
>     * I also updated the paths in the start.sh, apache-TEMPLATE.conf and
>     launcher-TEMPLATE.json files so that they reflect the correct path for
>     paraview-5.2 (which are bit different than paraview-4.4). By the way,
>     having start.sh running as a service at startup configuring
>     properly the
>     TEMPLATE files with the proper DNS name is admirable (each time I look
>     at the doc, config files or code, I am amazed by the quality of it,
>     thumb up!).
>     * when I navigate to the EC2 DNS, the Visualizer comes up and I can
>     browse for data files. The files seem to successfully load but nothing
>     show up in the camera (see snapshot 'aws_ec2_visu'). Looking at
>     the logs
>     on the machine, they don't report any error (and look similar to
>     what I
>     can get locally on my machine). There is a couple of errors showing up
>     in the web console though (in the snapshot attached).
>
>     It looks like I am very close to make it work, I am probably missing
>     something obvious.
>     I tried the following to solve it by using my configuration on my
>     local
>     machine:
>     1. update the apache-TEMPLATE.conf with the following rules:
>     RewriteCond %{QUERY_STRING} ^sessionId=(.*)&path=(.*)$ [NC]
>     RewriteRule ^/proxy.*$ ws://${session-to-port:%1}/%2 [P]
>
>     2. update the launcher-TEMPLATE.json with the following line:
>     "sessionURL" : "ws://DNS_NAME/proxy?sessionId=${id}&path=ws",
>
>     3. reboot (so that the files get updated)
>
>     but this time the UI doesn't even load, meaning I made it worse.
>
>     It seems just like a websocket connection issue, right?
>
>     Thanks in advance for any ideas to try.
>     cheers
>     claude
>
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