[racket] More interfaces to/from Liitin

From: Jukka Tuominen (jukka.tuominen at finndesign.fi)
Date: Thu Oct 27 07:48:04 EDT 2011


I wonder if there is anybody with Liitin account and access to a x-server
enabled client that could test the following shell command: (OSX in
particular haven't been tested, Ubuntu should work)

ssh -X -l USERNAME liitin.finndesign.fi
/afs/finndesign.fi/service/liitin/racket/bin/gracket -f

(all on one line, replace USERNAME with your Liitin username. Icon attached
if you want to create a launcher)

When executed, it should ask for a confirmation to contact the server (first
time only) followed by a Liitin password query.

If everything goes well, you should have your Liitin home object opening on
your desktop (app launcher by default). From there on, you will have full
access to all public and private Liitin objects, personal home directory on
global AFS tree, Linux apps and commands etc.
For example, try: Script-manager > Random script > Run
Or, (jtu100:drracket) run from Sript manager should open DrRacket with
Liitin environment.

For those interested in Liitin progress, more information below.

br, jukka


I earlier mentioned that it is possible to run Liitin client either on bare
metal, as a virtual machine or remotely over VNC. Some time later, a RCP
client/server was tried for providing a read-only connection to Liitin

Now there are a few more possibilities.

- You can boot Liitin client from a USB stick. It acts as if a read-only
Live CD, except that instead of starting from scratch each time, you can
access your full personal account. If you loose the stick, there's no trace
of your data. However, trasparently working and encrypted AFS cache survives
reboots reducing traffic over WAN. Soon you'll be able to deploy new Liitin
clients with it, or on a "headless" or otherwise unconfortable computer you
can just boot it as a node you can control from another Liitin client.

- On a X-client (Linux, OSX?, Win/Cyg-win or Xming?), you can "bring over"
your Liitin Home object (SSH/X-forward) to start it in a new window within
your current OS. From there on, you can execute further Liitin objects -
even private ones, launch new windows (e.g. DrRacket even if you haven't
installed it locally), access home directory etc. I personally prefer to do
it the other way around though; i.e. view external OS applications within
Liitin. Even most Windows applications are accessible through Wine. OSX
haven't been tried. Of course, you can do it between Liitin clients, as
well. Being able to create and manage virtual machines without leaving your
personal desktop is pretty nice as well (X-forwarded GUI).

- From Liitin, you can access other computers through SSH; execute commands,
transfer files and previously mentioned GUI applications. You can also
script mounting and unmounting remote resources, and for example sync
between two remote resources as if both local. I've done it from DrRacket.
According to the Liitin filosophy, there's no separate administrator or sudo
user. You can, however, ssh computers as root. All is handled from your
personal desktop and all computers have a similar interface, remote and

- In addition to launching the Home object through X-forwarding, you can use
a SSH script to launch any other Liitin object directly as well, Linux apps,
or just execute and/or return a object to be further used in an external
system. The overhead to make connection, initiate gracket and liitin
environment is substantial atleast for now, however. Again, this is done
through your own Liitin account, so you have access also to your private
Liitin objects and home directory. Having different PLT-Scheme and Racket
versions also available soon hopefully, you should be able to have an older
code run on a specific version and return the results on an external
computer, for example. And since it is a uniform and common environment to
all Liitin users, you can save the script as a Liitin object and share with
others, instead of merely instructing how it can be done.

Depending on the source and target computers, the SSH authentication can be
either interactice password, passwordless SSH key (scripts to create and
transfer key to a remote computer exist), or single-sign-on kerberos
delegation among trusted hosts. The last one should allow distributing
execution transparently among several, uniform Liitin clients.

Drawback: Currently, Liitin is utilizing less than 1/10 of the WAN bandwidth
which we are hoping to fix at some point. Before Moore will fix it, I hope.

|  J U K K A   T U O M I N E N
|  m a n a g i n g   d i r e c t o r  M. A.
|  Finndesign  Kauppiaankatu 13, FI-00160 Helsinki, Finland
|  mobile +358 50 5666290
|  jukka.tuominen at finndesign.fi  www.finndesign.fi

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