WildFly Class Loading

Migrating from https://home.feodorov.com:9443/wiki/Wiki.jsp?page=JBoss7ClassLoading

External

• Class Loading in AS7 https://docs.jboss.org/author/display/AS7/Class+Loading+in+AS7
• Module Compatible Class Loading Guide https://developer.jboss.org/wiki/ModuleCompatibleClassloadingGuide

Internal

• WildFly
• Modules

Overview

WildFly class loading relies on modules that have to define explicit dependencies on other modules. This model is different from the previous EAP 5 hierarchical class loading model. The implementation of the modular class loading system is provided by the jboss-modules library.

Class Loading Precedence

WildFly adds module dependencies for a JEE deployment in a very specific order, starting from the highest priority to the lowest priority:

1. System Dependencies - these are the dependencies that are automatically added by the container. For more details see implicit dependencies.
2. User Dependencies - these are the dependencies that are added through jboss-deployment-structure.xml, through the Dependencies: manifest entry for modules or through Class-Path: for JAR files.
3. Local Resources - class files packaged inside the deployment itself (example, classes from WEB-INF/classes or WEB-INF/lib in a WAR file.
4. Inter-Deployment Dependencies - dependencies on other deployments in an EAR deployment. This can include classes in an EAR's lib directory or classes defined in other EJB JARs.

Organizatorium

• WAR class loading https://docs.jboss.org/author/display/AS71/Developer+Guide#DeveloperGuide-WARClassLoading
• EAR class loading https://docs.jboss.org/author/display/AS71/Developer+Guide#DeveloperGuide-EARClassLoading