Losing Session Id Every Request in Spring 3 MVC Application with Proxy by Apache

I have a web application which I am setting up a shopping cart for; the application serves many different websites, each with it's own domain. Virtual Hosts are used to forward each domain to the Tomcat 6 server as well as set the path to that particular websites static resources; these static resources cannot be stored in the web application, and therefore are stored on the server and served through Apache.

first I use JkMount on my context root, then do URL rewrite with [P, L] for taking the context path "mywebapp" out of the URL, so when someone goes to this application with the domain somedomain.com the web application processes on somedomain.com/mywebapp/store/cart but the browser sees somedomain.com/store/cart. Until now this has been working very well; The problem is that every request is having it's session reset and I don't know why.

If I remove apache from the front end of serving the Session is not reset and works normally (as I expected). But I can't seem to set up my virtual host to forward to the application without losing sessions. I've read a lot about the problem but my competence is in JavaEE, and I have very little knowledge of Apache Web Server; so I'm not even sure how to begin researching the fix.

I've heard of something called ProxyPassing but I'm not sure what that means or how it works; most examples I've seen have changes to the Tomcat server.xml adding a domain, which I can't really do because domains (virtual hosts to match) get added dynamically and I can restart Apache, but can't be restarting the JavaEE application every time a new site is added.

Any ideas for fixing this, or getting to the root cause? Any alternative approaches?

UDPATE: I'm going to post my virtual host entry for one of the dynamic websites

    <VirtualHost *:80>
    ServerAdmin test@test.com
    DocumentRoot "C:/wamp/www"
    ServerName jawesome.com
    ServerAlias www.jawesome.com
    ErrorLog "logs/jawesome_com-error.log"
    CustomLog "logs/jawesome_com-access.log" common

    Alias /files/ "C:/static/1/uploaded_files/"
    <Directory "C:/static/1/uploaded_files">
                Options FollowSymLinks Indexes MultiViews
                Order allow,deny
                Allow from all
    </Directory>

    JkMount /webapp ajp13
    JkMount /webapp/* ajp13

    RewriteEngine on
    #RewriteLogLevel 9
    #RewriteLog "/usr/local/apache/logs/testrewrite.log"

    RewriteCond %{REQUEST_URI} !^/(webapp/.*|files/.*)$
    RewriteRule ^/(.*)$ /webapp/$1 [P,L]
</VirtualHost>

Solution

The Path needs to be removed from the JSESSIONID cookie. One option would be to remove it in your Tomcat setup. Add emptySessionPath="true" to your AJP Connector.

<Connector port="8009" protocol="AJP/1.3" redirectPort="8443" emptySessionPath="true"/>

The only gotcha is if you have other apps running on this same domain they would share this session id. But I don't see any in your config.