Web Application extensions consist of two parts: a JAR and a WAR. The JAR component contains the extended class files, while the WAR component contains the project configuration files. This separation of class files from project configuration files makes the web applications more robust and easier to maintain.

The JAR component has the following structure:

<ext-[webapp-name]>
   src  
      main
         java       
            // Extension classes go here 
         resources
            META-INF
               conf
                  [webapp-name]-plugin.xml    // Spring configuration for new and overriding beans goes here
   pom.xml

The WAR component has the following structure:

ext-[webapp-name]-webapp
   src
      main
         filtered-resources
            module.properties   // Template file used to set Spring property values at build-time. For more info, see Build-time property configuration.
         webapp
            WEB-INF
               misc
                  log4j.properties
               spring
                  ep-monitoring.xml        // Health check configuration
               elastic-path-servlet.xml    // Entry point for loading Spring configuration
               web.xml                     // WAR configuration
   pom.xml