In this chapter, you will learn how to create a cluster for a web application spread across two or more WildFly nodes. Clustering is the capability to continue serving a client, even in case of failures (that is, a server crash), and is also known as failover.

For example, suppose you are filling in a long form, in a large number of steps (where steps are meant to be pages). Now suppose that in the last step, the server or the WildFly node crashes, you would have to refill all the information again. Surely, you will not use that site anymore, if you can choose to do so. By the way, how would you address such a problem? Clustering is the answer.

In clustering, you get the user's session replicated to your cluster nodes. So in case of a failure, in the next HTTP request, you will land on a different server/node, which will continue serving you just as though nothing happened—obviously, the end user will...