This is how I use mod_proxy in order to have apache proxy to the tomcat server. It's recommended to understand how mod_proxy works because it's easy to turn your apache server into an "open web proxy" if it's misconfigured. {{{ProxyRequests off}}} is a good option to use.

I've put this in a virtual host declaration:

{{{ProxyPass /wiki/    http://localhost:8080/JSPWiki/
ProxyPassReverse /wiki/     http://localhost:8080/JSPWiki/}}}

The jspwiki is accessed by http://virtualhost/wiki/

[http://httpd.apache.org/docs/mod/mod_proxy.html]

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An alternative option is to use the [AJPv13 Protocol|http://jakarta.apache.org/tomcat/connectors-doc/common/ajpv13a.html] through the use of JK connectors. 

Just download the module, load it in Apache, create and customise a {{workers.properties}} (or {{workers2.properties}} in the case of JK2) file in the Apache {{conf}} directory and it will connect to Tomcat using the appropriate connector (configured by default in Tomcat's {{server.xml}}). 

This is a more efficient way of achieving the same effect as a reverse proxy.

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If you require editors to set a cookie in order to edit a page, ProxyPassReverse won't work.
Then you need to configure Tomcat with proxy support too. Like this:

* Edit server.xml
* Identify the connector which listens to port 8080 (search for port="8080")
* Add __proxyPort="80"__
* Add __proxyName="virtualhost"__ where virtualhost is the name of your host
* Restart Tomcat

[Tomcat 4.1 Proxy Howto | http://jakarta.apache.org/tomcat/tomcat-4.1-doc/proxy-howto.html]