dhis2-users team mailing list archive

[Steven Uggowitzer <whotopia@xxxxxxxxx>]

There are a variety of possibilities available to virtually simulate
communications links with limited bandwidth, high latency and packet loss.
For my own needs, I built a WIFI access point with custom firmware based on
OpenWRT implementing KauNet:
http://www.kau.se/en/kaunet
https://halshs.archives-ouvertes.fr/file/index/docid/388811/filename/hose-kaunet-iwssc2009.pdf
If anyone's interested, I could probably virtualise this for qemu or VMWare
and put it up on GitHub. The simulation algorithm possibilities in this
solution are great, but it's a bit complicated to set up.

However, there is perhaps a quick and simple solution, which does not
simulate quite as accurately, but should give you a better idea about what
life behind a slow link is like.  You'll need DHIS2 installed on Linux.
Then have a look at:

https://gist.github.com/denilsonsa/5176e1c9b6a119594ce0

This project essentially consists of one shell script that manipulates
traffic control parameters on a Linux ethernet interface.

In my case, on my Ubuntu DHIS2 server in VMWare , I simply typed:

*git clone https://gist.github.com/denilsonsa/5176e1c9b6a119594ce0
<https://gist.github.com/denilsonsa/5176e1c9b6a119594ce0>*
*cd 5176e1c9b6a119594ce0*
*sudo ./slow vsat-busy*

and presto, accessing the DHIS2 instance (remotely on the IP address for
ETH0) became very noticeably slower.
*sudo ./slow modem-2.4k *
was REALLY slow. Then
*sudo ./slow reset*
restores ETH0 to normal.  Help is called up via:
*./slow -h*
Usage: slow <network-type> [-d device] [-b bandwidth] [-l latency] [-p drop]

       slow reset
       slow status

"network-type" type can be:

  GPRS
  GSM
  EDGE
  2.5G
  GPRS
  3G
  4G
  modem-2.4k
  modem-9.6k
  modem-14.4k
  modem-28.8k
  modem-56k
  56k
  T1
  T3
  DSL
  cablemodem
  wifi-a
  wifi-b
  wifi-g
  wifi-n
  eth-10
  eth-100
  eth-1000
  vsat
  vsat-busy

If you'd like a high level overview of process network utilisation, i.e. to
make sure that the above script is actually doing it's job, try installing
NetHogs.  This nice small program (similar to Linux top command) keeps a
tab on each process' network activity on your system. It also keeps track
of real time network traffic bandwidth used by each program thread or
application.

*sudo apt-get install nethogssudo nethogs*


Best regards,
Steven


-- 
--------------------------
Steven Uggowitzer
eSHIfT Partner Network,  Entuura Ventures Ltd
Mob: +41 79 719 4180
Skype: fendant123
LinkedIn: http://ch.linkedin.com/in/stevenuggowitzer


On Sun, Nov 16, 2014 at 5:31 PM, Knut Staring <knutst@xxxxxxxxx> wrote:

> Hello list,
>
> Has anyone been using DHIS2 over a satellite connection, e.g. Thuraya?
>
> Bob told me this: "Satellite will be very high latency connection.  Dhis2
> is well tested for low bandwidth requirements.  I am not sure how much we
> have tested ajaxy stuff with high latency.  Of course it should work, but
> there may be some unexpected user experiences."
>
> Would be great to hear from anyone who has actually tried this.
>
> Thanks,
> Knut
>
> --
> Knut Staring
> Dept. of Informatics, University of Oslo
> Liberia: +231 770 496 123 or +231 886 036 837
> Norway: +4791880522
> Skype: knutstar
> http://dhis2.org
>
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