Java Reference
In-Depth Information
Clustering basics
A cluster of application servers consists of multiple server instances (cluster nodes) running
simultaneously and working together to provide increased scalability and reliability. The
nodes that make up a cluster can be located either on the same machine or different ma-
chines. 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:
•
Horizontal scalability (scaling out)
: Adding a new node to a cluster should allow
the overall system to service a higher client load than that provided by a simple ba-
sic 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 that compose
the cluster should each process a fair share of the overall client load. This can be
achieved by distributing client requests across multiple servers, which is also
known as load balancing.
•
High availability
: Applications running in a cluster can continue to do so when a
server instance fails. This is achieved because applications are deployed on mul-
tiple nodes of the cluster, and so if a server instance fails, another server instance
on which that component is deployed can continue with application processing.
