Technical data

What Is a Domain?
Configuring and Managing WebLogic Server 2-5
You can create a non-clustered Managed Server and add it to a cluster by configuring
pertinent configuration parameters for the server instance and the cluster. Conversely,
you can remove a Managed Server from a cluster by re-configuring the parameters
appropriately. The key difference between clustered and non-clustered Managed
Servers is support for failover and load balancing—these features are available only in
a cluster of Managed Servers.
Your requirements for scalability and reliability drive the decision on whether or not
to cluster Managed Servers. For example, if your application is not subject to variable
loads, and potential interruptions in application service are acceptable, clustering may
be unnecessary.
For more information about the benefits and capabilities of a WebLogic Server cluster,
see “Introduction to WebLogic Server Clustering” in Using WebLogic Server Clusters
A single domain can contain multiple WebLogic Server clusters, as well as multiple
Managed Servers that are not configured as clusters.
Resources and Services
In addition to the Administration Server and Managed Servers, a domain also contains
the resources and services required by Managed Servers and hosted applications
deployed in the domain.
Examples of domain-level resources include:
! Machine definition identify a particular, physical piece of hardware. A Machine
definition is used to associate a computer with the Managed Server(s) it hosts.
This information is used by Node Manager in restarting a failed Managed
Server, and by a clustered Managed Server in selecting the best location for
storing replicated session data. For more information about Node Manager, see
“Overview of Node Manager” on page 3-1.
! Network channels, an optional resource that can be used to define default ports,
protocols, and protocol settings. After creating a network channel, you can
assign it to any number of Managed Servers and clusters in the domain.
See“Configuring Network Resources” on page 11-1 for more information.
Managed Servers in the domain host their own resources and services. You can deploy
resources and services to selected Managed Servers or to a cluster. Examples of
deployable resources include:
! application components, such as EJBs