There Is No “Cluster” in Java EE
Very often, when talking/training/sharing about Java EE, I get the same question: What about clustering in Java EE? The answer is: nothing, rien, nada, ezer, nista, niets! There is nothing about clustering (failover, load-balancing…) in JavaEE. And to prove it, I’ve looked for the word “cluster” in the 4.171 pages of the 19 more important Java EE 7 specifications. The word “cluster” only appears once :
EE.5.2.2 – Application Component Environment Namespaces
java:global – Names in this namespace are shared by all applications deployed in an application server instance. Note that an application server instance may represent a single server, a cluster of servers, an administrative domain containing many servers, or even more
As you can see, there is nothing about clustering in the Java EE specifications. Some vendors might implement it, but that’s another “proprietary” story.