The application seen earlier used Tiles in a single application module. In this section you will see Tiles works across modules. Tiles provides two modes of operation: Non-module-aware and module-aware modes. They are distinguished by the setting moduleAware attribute on the Tiles PlugIn. The definition file is specified by the definitions-config attribute on the Tiles PlugIn.
In non-module-aware mode, all modules use the same tiles definition file specified in the struts-config.xml for the default module. If there is no default module, all modules use the tiles definition file specified in the struts-config.xml for the first module listed in web.xml.
In module-aware mode, each module has its own tiles definition file. A module cannot see definitions in a tiles definition file belonging to another module unless it uses that file itself.