Load balancing uPortal behind Apache (HTTP Server) is a common and in-expensive
way expensive way to host a single uPortal service across multiple servers.
...
Apache JServ Protocol is a binary protocol used to proxy inbound requests from
a from a web server (e.g. Apache) to application servers. AJP is commonly used with
Apache with Apache and Tomcat.
Choosing A Plugin
Apache Web Server is a long-standing project with a large ecosystem of plugins.
It It is no surprise that there are multiple ways to configure Apache and Tomcat
servers Tomcat servers given this fact.
Mod_JK
The mod_jk plugin is fairly old. It is still functional and many experienced
implementors experienced implementors are familiar with it. This is the main motivation to use this plugin
over plugin over the mod_proxy_ajp.
...
The mod_proxy_ajp plugin is part of the modern mod_proxy* set of plugins. These
have These have a consistent style of configuration. Implementors with mod_proxy experience
will experience will likely favor this plugin.
...
One consideration is whether to host Apache separately in it's own
server own server or host it with a Tomcat (web container). Note that while the approach
detailed approach detailed below is specific to Apache and Tomcat, similar solutions for other
containers other containers should be easy to find. An advantage of having a Tomcat with Apache
is Apache is that as long as the load balancing server is running correctly, it the service
is service is available. Connection loss to other Tomcats, although performance will
likely will likely suffer. The downside is a potential that a flakey Tomcat on the
load balancer may compromise the whole service if it brings down this
critical this critical server. The nice part of this decision is that configuring
Tomcat configuring Tomcat local to Apache can be done the same as for remote Tomcats. They are
independent independent even with hosted on the same server.