This illustration shows the Development Application directory structure, with applications/<appname>/ as the root directory. There are four sub-directories under the root directory: META-INF, <ejb_module>, <web_module>, and <client_module>:
The META-INF directory contains a single file: application.xml.
The <ejb_module> directory contains two sub-directories: EJB classes (with a note stating that my.ejb.class maps to the /my/ejb/class dirctory), and META-INF, which contains two files: ejb-jar.xml, and orion-ejb-jar.xml.
The <web_module> directory cotnains the index.html file, as well as the JPS pages and WEB-INF sub-directories. The WEB-INF directory in turn contains the web.xml and orion-web.xml files, as well as the classes and lib sub-directories. The classes directory contains Servelet classes, while the lib directory contains dependent libraries (with a note stating that my.Servlet maps to /my/Servlet). 
The <client_module> directory contains the Client classes and META-INF sub-directories. The META-INF directory contains the application-client.xml and orion-application-client.xml files.