The difference between standalone and domain reflects in the directory layout of the application server is shown in the following diagram:

As you can see in the preceding diagram, the WildFly directory layout is divided into two main parts: the first one is pertinent to a standalone server mode and the other is dedicated to a domain server mode. Common to both server modes is the modules directory, which is the heart of the application server.

WildFly is based on the JBoss Modules project, which provides an implementation of a modular (nonhierarchical) class loading and an execution environment for Java. In other words, rather than a single class loader that loads all JARs into a flat class path, each library becomes a module, which only links to the exact modules it depends on and nothing more. It implements a thread safe, fast, and highly concurrent delegating class loader model, coupled with an extensible module resolution system. This combines to form a unique...