In some architectures, it is useful to put an Apache web server in front of the JBoss server. External web clients talk to an Apache instance, which in turn speaks to the Tomcat instance on behalf of the clients. Apache needs to be configured to use the mod_jk module which speaks the AJP protocol to an AJP connector running in Tomcat. The provided server.xml file comes with this AJP connector enabled.

<Connector port="8009" address="${jboss.bind.address}"
           enableLookups="false" redirectPort="8443" debug="0"
           protocol="AJP/1.3" />

You'll need to consult the Apache and mod_jk documentation for complete installation instructions. Assuming you have a properly configured Apache instance, the following configuration fragment shows an example of how to connect with a WAR deployed with a context root of /jbosstest.

...
LoadModule jk_module libexec/mod_jk.so
AddModule mod_jk.c
           
<IfModule mod_jk.c>
    JkWorkersFile /tmp/workers.properties
    JkLogFile /tmp/mod_jk.log
    JkLogLevel debug
    JkMount /jbosstest/* ajp13
</IfModule>

The workers.properties file contains the details of how to contact the JBoss instance. For more details on how to front Apache for JBoss, especially for a cluster of JBoss servers, please refer to JBoss 4 Clustering Guide.