A cluster is an assembly of terminals or computers that are assembled through internetwork connection to address a large processing requirement through parallel processing. Hence, clusters are usually configured with terminals or computers that have higher processing capabilities connected with high-speed internetwork. Usually, a cluster is considered an image that integrates a number of nodes with a group of resource utilization techniques.

The following diagram is a sample clustered Tomcat server for a typical J2EE web application deployment:

The following table shows some of the important performance characteristics of the different parallel architecture systems discussed so far: