Mailing List Archive

On Jun 15, 2004, at 6:14 AM, jh@netfielders.de wrote:
> If I have a webserver with mod_backend installed, which passes
> requests to backend-servers with also mod_backend installed, are the
> scripts passed through, or does it need the same filebase (common
> fileserver) ?

It's mod_backhand, not mod_backend.

> Example:
> Having a script which is generating images, how actualy does
> mod_backhand work ? Are the images saved on the backend server, or on
> the frontend which recieves the requests ?

It passes the request back just as mod_proxy would do in the reverse
proxy scenario. If it always passes the request back, you actually do
not need the script on the front-end machine at all. The script (or
files) must present on whichever machine ultimately services the
request.

// Theo Schlossnagle
// Principal Engineer -- http://www.omniti.com/~jesus/
// OmniTI Computer Consulting, Inc. -- http://www.omniti.com/
// Ecelerity: fastest MTA on Earth

On Tue, 15 Jun 2004 12:14:03 +0200, <jh@netfielders.de> wrote:

> Hi !
>
> If I have a webserver with mod_backend installed, which passes requests
> to
> backend-servers with also mod_backend installed, are the scripts passed
> through, or does it need the same filebase (common fileserver) ?

Yes, it does. NFS mounts work well, but I prefer to use 'dssh' for
managing the cluster.

See http://dcmd.sourceforge.net for the source code, and
http://www.samag.com/documents/s=8892/sam0310e/sam0310e.htm
for an article explaining its usage.

What I tend to do is install things on my 'master' front-end server and
then
just 'dscp /opt/ap_b/cgi-bin/* []:/opt/ap_b/cgi-bin/' which installs the
codebase on all the farm machines.


> Example:
> Having a script which is generating images, how actualy does mod_backhand
> work ? Are the images saved on the backend server, or on the frontend
> which recieves the requests ?

mod_backhand organises passing the request for the URL to one of the
machines in your cluster, and passing the response from that machine to
the calling party. If (say) you have 10 machines with a script on them
which creates an image, saves it in /tmp/ and then serves it out then
after doing one request you'll have one of your 10 machines with an image
in /tmp/. Which one that is depends on how you've configured the candidacy
and sorting functions.

Regards,
_Gus



--
Angus M Wood
Chief Architect
Inspired Broadcast Networks
www.inspiredbroadcast.net
Out of Home Pay to Play Networked Entertainment
1st Floor, 1-7 Livonia Street, London, W1F 8AD
Tel: +44 20 7287 5813
Mob: +44 7767 393039
Fax: +44 20 7287 0131

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