Server Instance
Theserver instance is a single Java EE compatible Java Virtual Machine hosting an Enterprise
Serveron a single node. Each server instance has a unique name in the domain. A clustered
serverinstance is a member of a cluster and receives all of its applications, resources, and
congurationfrom its parent cluster; ensuring that all instances in the cluster are
homogeneous.An unclustered server instance does not belong to a cluster and as such has an
independentset of applications, resources, and conguration. The following gure shows an
applicationserver instance in detail. The application server instance is a building block in the
clustering,load balancing, and session persistence features of the Enterprise Server.
TheSun GlassFish Enterprise Server creates one application server instance, called server,at
thetime of installation. For many users, one application server instance meets their needs.
However,depending upon your environment, you might want to create one or more additional
applicationserver instances. For example, in a development environment you can use dierent
applicationserver instances to test dierent Enterprise Server congurations, or to compare
andtest dierent application deployments. Because you can easily add or delete an application
serverinstance, you can use them to create temporary sandbox area for experimentation
purposes.
Inaddition, for each application server instance, you can also create virtual servers. Within a
singleinstalled application server instance you can oer companies or individuals domain
FIGURE1–1 EnterpriseServer Instance
EnterpriseServer Concepts
Chapter1 • Enterprise Ser ver Overview 29