IRS JBoss Admin II Study Guide

JBoss EAP 7.1 supports applications that adhere to Java Enterprise Edition v7. For a complete matrix of EAP versions and associated JEE versions, see this article.
JBoss EAP 7 and later support a new module system so as to alleviate issues with Java libraries and so-called "JAR Hell" that were present in the traditional classloader approach. In addition, JBoss itself comprises modules so the server can start faster and leaner, only loading required modules.

Every module has a name -- the module's name and its directory structure in JBoss must match exactly. Each module also needs a file named module.xml that configures the module, including its exports and dependencies.
JBoss administrators can configure JBoss in three different ways:
1. Direct editing of the XML. This is a comprehensive technique that lets you do any kind of configuration, but requires extensive knowledge of XML syntax and also typically requires a server restart.
2. Using the Command Line Interface (CLI). This is a comprehensive technique, but has an arcane syntax with a considerable learning curve. It also allows administrators to write scripts to automate frequently performed configuration actions.
3. Using the web-based Admin Management Console (a.k.a Management Console). This technique is easy to use and learn, but does not provide all of the capabilities of the other two approaches.
JBoss configuration information is stored in XML, but as discussed above, you can modify the configuration using tools. One of the commonly-modified elements in the XML is the <subsystem> element, in which the various subsystems of JBoss are configured, e.g. logging, messaging-activemq and so forth.

The set of subsystems available in a given configuration is referred to as a profile. In standalone mode, there are separate XML files with different profiles and thus different subsystems and corresponding capabilities.
In a configuration file, an interface is a named element that ultimately binds to the underlying network. The default configuration defines two <interface> elements, both of which bind to localhost (127.0.0.1) by default:
- The public interface which binds using port 8080
- The management interface which binds using port 9990.
In standalone mode (no remote management), clustering is supported by the subsystems predefined in the XML files ending with *-ha.xml, e.g. standalone-ha.xml and standalone-full-ha.xml.
Many JBoss admins prefer to use the CLI as the primary management tool. One nice feature of the CLI is the ability to quickly examine the current state of the management objects. For example, on any node, you can invoke the :read-resource operation to list all of its attributes and child nodes.