Chapter 4. The Structure of JBoss EAP 6
The key features of JBoss EAP 6 are a modular class-loading structure and a domain framework which centralizes configuration in a single controller. These two features have one big asset in common: flexibility. The idea is to start with a small, lightweight application server and then add in the modules for the desired functionality and the server instances for a naturally distributed system.
JBoss ON works within the changeability of that system to bring clarity into how those modular, distributed resources are related and to provide an extra skin of both administrative control and information visibility.
JBoss ON imposes a hierarchy and structure on JBoss EAP 6 installation, but before you can have an idea of how that structure is applied, it helps to have an understanding of the order that EAP 6 itself has.
Note
JBoss EAP 6 topologies for standalone and domain servers are described in the JBoss AS 7 project documentation.
4.1. "Classic" Structure: Standalone Servers
Most of the functionality for the JBoss EAP 6 server is implemented through independent classes or subsystems. Which subsystems a server uses, and their configuration properties or configured instances, are defined in a profile.
A standalone instance for EAP 6, much as in EAP 5, is a collection of those defined subsystems, a set of socket bindings to define communications, network interfaces, and other settings.
The entire server instance is defined in its
standalone.xml file. Almost every entry in that file is identified as a child of the server. For example, these subsystem entries create the ee and jmx child resources for the server:
<subsystem xmlns="urn:jboss:domain:ee:1.1"/>
<subsystem xmlns="urn:jboss:domain:jmx:1.1">
<show-model value="true"/>
<remoting-connector/>
</subsystem>
Likewise, socket bindings, network interfaces, and deployed content, which are defined in the configuration file, are discovered as resources.
Subsystems like datasources and logging configuration can have multiple instances defined; these are all configured as child resources of the subsystem. Because of the modular nature of the EAP 6 server, the exact subsystems — and therefore the exact children in JBoss ON — vary with the subsystem and other definitions in the configuration file.
Overall, because of the number of subsystems and other configuration settings, the standalone server has a very wide, flat, and shallow inventory tree. JBoss ON imposes little additional hierarchy on the standalone server structure. It reflects the way the server is configured in
standalone.xml.
Figure 4.1. Standalone Server Configuration
Management and operations for the standalone server are self-contained. Every child node for the standalone server combines both its configuration and its runtime environment (monitoring, alerting, and operations) in the same location. To change the configuration for a datasource, for example, edit the datasource entry directly. Every standalone server is managed independently of any other server, even in the same cluster or the same machine.
All of this is comparable to the structure and functionality of a JBoss EAP 5 server, with some slight differences in the organization of the inventory.
