Java Reference
In-Depth Information
Chapter 10. Clustering JBoss AS 7
Applications
In the former chapters, we went through the most interesting aspects of Java Enter-
prise development. Once you are ready to rollout your applications, it is mandatory
that you guarantee your customers a responsive and reliable environment. This re-
quirement is usually achieved through application server clustering.
JBoss clustering is not the product of a single library or specification, but rather
a blend of technologies. In this chapter, we will first introduce some basics about
clustered programming. Next, we will quickly move to the cluster configuration and
setup, which will be required to deploy some clustered applications.
Here is a preview of what we will learn from this unit:
• What clustering is, and how JBoss AS implements it
• Setting up a standalone and a domain of application server clusters
• Developing clustered Java EE 6 applications in order to achieve load bal-
ancing and high availability
Clustering basics
A cluster of application servers consists of multiple server instances (cluster nodes)
running simultaneously and working together to provide increased scalability and reli-
ability. The nodes that make up the cluster can be located either on the same machine
or on different machines. From the client's point of view, this is irrelevant because the
cluster appears as a single server instance.
Introducing clustering in your applications will produce the following benefits:
•
Scalability
: Adding a new node to a cluster should allow the overall sys-
tem to service a higher client load than that provided by the simple basic
configuration. Ideally, it should be possible to service any given load simply
by adding the appropriate number of servers or machines.
•
Load balancing
: In a clustered environment, the individual nodes com-
posing the cluster should each process a fair share of the overall client
