Apache and multiple back-end servers

Hi all,

I am new to web applications. I have the following question. I have a
web server and two servers that run a heavy emmulation program. This
is what I want: when a user wants to run the program the apache server
will look at which server is free and send through php a series of
commands to that particular machine. Currently the system works with
just one back-end server. I want to add another one.

This shouldnt be difficult but I am not really sure what to look for
on the net and the newsgroups. Any hints?

Thank you in advance

On 27 Feb, 11:23, tolis.junk.ema...@gmail.com wrote:
> Hi all,
>
> I am new to web applications. I have the following question. I have a
> web server and two servers that run a heavy emmulation program. This
> is what I want: when a user wants to run the program the apache server
> will look at which server is free and send through php a series of
> commands to that particular machine. Currently the system works with
> just one back-end server. I want to add another one.
>
> This shouldnt be difficult but I am not really sure what to look for
> on the net and the newsgroups. Any hints?
>
> Thank you in advance

do both machines have web servers running on them? if they do I assume
its for more than communicating with the front end server, and given
that they do couldnt you just have a script on both back end machines
that does a top and finds the free CPU/mem, the front end server can
then get the 2 outputs and make the decision as to which back end
server to send the command string to.
This is all given that you do it this way - with 3 servers each
running some kind of web server!

> do both machines have web servers running on them? if they do I assume
> its for more than communicating with the front end server, and given
> that they do couldnt you just have a script on both back end machines
> that does a top and finds the free CPU/mem, the front end server can
> then get the 2 outputs and make the decision as to which back end
> server to send the command string to.
> This is all given that you do it this way - with 3 servers each
> running some kind of web server!

The PCs are running Matlab. The user provides some parameters to the
apache and then the apache sends this parameters to matlab. But since
it takes time for the the completion of the script (matlab) i want to
add multiple PCs and have apache (???) distribute the load to the
available PCs

On 27 Feb, 13:25, apostolos.georga...@gmail.com wrote:
> > do both machines have web servers running on them? if they do I assume
> > its for more than communicating with the front end server, and given
> > that they do couldnt you just have a script on both back end machines
> > that does a top and finds the free CPU/mem, the front end server can
> > then get the 2 outputs and make the decision as to which back end
> > server to send the command string to.
> > This is all given that you do it this way - with 3 servers each
> > running some kind of web server!
>
> The PCs are running Matlab. The user provides some parameters to the
> apache and then the apache sends this parameters to matlab. But since
> it takes time for the the completion of the script (matlab) i want to
> add multiple PCs and have apache (???) distribute the load to the
> available PCs

you can do this, I suggest the setup
front end "job server" with mysql, or sqlite list of jobs pushed to it
by users. Make sure to only push correct jobs!

as many other machines as you need all running a process monitor
either as a service or as a cron job, when they detect that the local
matlab process has finished, they request and execute the next job
from the front end server.

The cheapest of all cheap ways to do this would be to ensure that the
front end server actually returned the job in the file format that
could be executed directly, (check that the job is what it should be
for security) and use

cronw version 2, tasklist in a batch job
to check the local process table

and wget for windows to retrieve the job to be executed.

Of course there are much better ways but this would be doable in short
order.


I use cronw2 myself on windows, it has a small footprint of 2M and
jobs are added via a text file crontab.txt just like unix. It runs as
a windows service. It's 100% on my machines. wget is just a real handy
commandline http/ftp tool a steal again from unix/linux very handy.