Question on mod_rewrite

[Adinarayana Kadiyam <na...@mahindrabt.com>]

Hi,
    We have got two apache webservers running at two diffrent machines.(let
s say the urls are http://site1.domain.com:7777 and 
http://site2.domain.com:7778 ) I am using another instance of apache
webserver on site1.domai.com, running at port 7000.
    I want to distribute URL requests between http://site1.domain.com:7777
and http://site2.domain.com:7778 based on the cookie value. I included the
following 
lines in httpd.conf to enable this load balancing(proxy throughput method)

RewriteEngine   on
RewriteLog      "/path/to/rewrite.log"
RewriteLogLevel 0
RewriteLock     "/path/to/rewrite.lock"

RewriteMap      lb      prg:/path/to/lb.pl
RewriteRule     ^/(.+)$ ${lb:$1:%{HTTP:Cookie}} [P,L]

    When I connect to http://site1.domain.com:7000, it gets index page from
one of the backend servers and displays it on the browser. 
After entering my username and passwd in the index page I click on submit
button. The request will go 
to http://site1.domain.com:7000 and that will send this request to one of
the back end servers. The back end server sets username 
and serverid as cookies.

( The back end servers are DEC machines)

Here are the two cases.

1) when I directly connect to one of the backend servers like http://site1
domain.com:7777, supplying username and passwd and click 
on submit button
the following two lines are present in the HTTP header ( captured through
ethereal)
Set-Cookie: serverid=1.2.3.1
Set-Cookie: username=xxxxx

2) when I connect to one of the backend servers through intermediate
instance ( server at 7000) and 
capture the HTTP header, the following lines are present
Set-Cookie: serverid=1.2.3.1
X-Cache: MISS from site1.domain.com

    Why is this difference ? When I print the cookie value in lb
pl(mentioned in RewriteMap), it displays 
serverid=1.2.3.1. The username cookie is missing. What could be the reason ?

Thanx,
Adi 

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