WebLogic Clustering

Clustering  in WebLogic

A WebLogic domain can be composed of a number of WebLogic instances, and several of these servers may be grouped into clusters. The Domain is the parent of a Cluster. It contains typically one Admin and one or more Managed servers. Now the Cluster is a grouping of some or all of these managed servers within the domain.For instance, you could set up a cluster of WebLogic servers, all of which host your web application and related resources. This cluster of servers could be fronted by a load balancer that distributes requests evenly across all the members of the cluster. The load balancer could itself be another WebLogic instance. All server instances must belong to the same WebLogic domain. 

Thus, a WebLogic cluster is a group of servers working together with services, such as clustered JNDI, to provide support for failover and load balancing. A domain may in turn have a number of WebLogic instances, several groups of which can be placed into different clusters.