MBean Attribute.

When a domain is active, WebLogic Server instantiates a collection of Managed Beans (MBeans) to represent the items that are defined by the domain's schema. For example, the xs:complexType `serverType` is represented by an MBean named `ServerMBean`.

The xs:element `listen-port` within `serverType` is represented by the `ListenPort` attribute of `ServerMBean`.

An MBean is a Java bean that provides a Java Management Extensions (JMX) interface. JMX is the J2EE solution for monitoring and managing resources on a network. Like SNMP and other management standards, JMX is a public specification and many vendors of commonly used monitoring products support it.