13.4. Apache mod_jk

13.4.1. About the Apache mod_jk HTTP Connector

mod_jk provides HA clustering if you use the Apache Tomcat container instead of the built-in JBoss Web container. The mod_jk connector is maintained by Apache. Its documentation is located at http://tomcat.apache.org/connectors-doc/.
The JBoss Enterprise Application Platform can accept work loads from an Apache HTTPD proxy server. The proxy server accepts client requests from the web front-end, and passes the work to participating JBoss Enterprise Application Platform servers. If sticky sessions are enabled, the same client request always goes to the same JBoss Enterprise Application Platform server, unless the server is unavailable.
Unlike the mod_cluster JBoss HTTP connector, an Apache proxy server does not know the status of deployments on servers or server groups, and cannot adapt where it sends its work accordingly.
The advantages of Apache mod_jk are that it communicates over the AJP 1.3 protocol, and that it is available for Red Hat Enterprise Linux 5 and Microsoft Windows servers without a JBoss Enterprise Web Server entitlement.
Unless you need to use the AJP protocol or you need to run Red Hat Enterprise Linux 5 operating system, mod_cluster is the recommended load balancer because it integrates tightly with the web server and the JBoss Enterprise Application Platform. mod_cluster runs on Red Hat Enterprise Linux 6 and Microsoft Windows servers, over the HTTP and HTTPS protocols. For more information on mod_cluster, refer to Section 13.3.1, “About the mod_cluster HTTP Connector”.