Defining Application Server Instances

Application server instances form the basis of an application deployment. Each instance belongs to a single domain and has its own directory structure, configuration, and deployed applications. Each server instance also includes the Java EE platform web and EJB containers. Every new server instance must contain a reference to a node agent name defining the machine on which the instance will reside.

You cannot create Application Server instances on a developer domain. A developer domain is always associated only with the default instance, server1. To create multiple instances, you need to create a domain with the cluster profile. For information on creating domains, see the manpage for the command create-domain or consult the Admin Console Online Help.

You can create three types of server instances:

• In the standalone server instance the configuration is not shared by any other server instance or clusters.

• In the shared server instance the configuration is shared with other instances or clusters.

• In the clustered server instance the configuration is shared with other instances in the cluster.

  A cluster is a group of server instances sharing the same set of applications, resources, and configuration information. A server instance can belong to only one cluster. Among other things, the cluster is used to facilitate load balancing, through distribution of a load across multiple machines, and high availability, through instance level failover.