13.3. Web, HTTP Connectors, and HTTP Clustering

13.3.1. About the mod_cluster HTTP Connector

mod_cluster is the module which enables load balancing in the JBoss Web container. It is referred to as a connector. Which connector you use depends on which web container you choose to use with the JBoss Enterprise Application Platform. To learn about other connectors, refer to one of the following:
The mod_cluster connector has several advantages.
  • mod_cluster Management Protocol (MCMP) is an additional connection between the application server nodes and httpd, used by application server nodes to transmit server-side load balance factors and lifecycle events back to the web container via a custom set of HTTP methods.
  • Dynamic configuration of HTTPD proxies allows the JBoss Enterprise Application Platform to adapt on the fly, with no additional configuration.
  • The application servers perform the load-balancing factor calculations. This makes load balancing metrics more accurate than other connectors.
  • mod_cluster gives fine-grained application lifecycle control. Each server forwards any web application context lifecycle events to the proxy, informing it to start or stop routing requests for a given context in the server. This prevents end users from seeing 404 errors due to unavailable resources.
  • AJP is optional. Apache HTTP requires the use of AJP, but mod_cluster can use HTTP, HTTPS, or AJP.